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      <title>Konstantin Matsiushonak: a journey into programming</title>
      <link>https://kakoc.blog</link>
      <description>Konstantin Matsiushonak&#x27;s blog</description>
      <generator>Zola</generator>
      <language>en</language>
      <atom:link href="https://kakoc.blog/rss.xml" rel="self" type="application/rss+xml"/>
      <lastBuildDate>Tue, 01 Dec 2020 00:00:00 +0000</lastBuildDate>
      <item>
          <title>MYOX: Javascript bundler</title>
          <pubDate>Tue, 01 Dec 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox-js-bundler/</link>
          <guid>https://kakoc.blog/blog/myox-js-bundler/</guid>
          <description>&lt;p&gt;&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox&#x2F;&quot;&gt;MYOX: what does it mean?&lt;&#x2F;a&gt;&lt;&#x2F;p&gt;
&lt;h2 id=&quot;preface&quot;&gt;Preface&lt;a class=&quot;zola-anchor&quot; href=&quot;#preface&quot; aria-label=&quot;Anchor link for: preface&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Have you heard&#x2F;used Webpack, Bable? Wanted to understand the basic ideas behind them?&lt;&#x2F;p&gt;
&lt;p&gt;In this blog post I&#x27;m going to create Javascript bundler and demonstrate how things like Bable can be leverage there. But we won&#x27;t use Bable.
In Rust ecosystem we have our own Bable which is called &lt;a href=&quot;https:&#x2F;&#x2F;github.com&#x2F;swc-project&#x2F;swc&quot;&gt;swc&lt;&#x2F;a&gt;.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;final-goal&quot;&gt;Final goal&lt;a class=&quot;zola-anchor&quot; href=&quot;#final-goal&quot; aria-label=&quot;Anchor link for: final-goal&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Firstly let&#x27;s determine our final goal.&lt;br &#x2F;&gt;
Our goal is to write Javascript bundler which can bundle basic &lt;strong&gt;React hello world&lt;&#x2F;strong&gt; application:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; index.js
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;* &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;as &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;React &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;react&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;* &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;as &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ReactDOM &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;react-dom&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;class &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Hello &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;extends &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;React&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;font-style:italic;color:#b06936;&quot;&gt;Component &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;render&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;React&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;createElement&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;div&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;null&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;`Hello ${&lt;&#x2F;span&gt;&lt;span style=&quot;color:#acb3c2;&quot;&gt;this&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#acb3c2;&quot;&gt;props&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#acb3c2;&quot;&gt;toWhat&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;}`&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;  }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ReactDOM&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;render&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;React&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;createElement&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;Hello&lt;&#x2F;span&gt;&lt;span&gt;, {toWhat: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;World&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;}, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;null&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;document&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;getElementById&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;root&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;The bundle process should be like:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; run &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;path_to_entry.js_file&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;## it will produce out.js file
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Produced &lt;strong&gt;out.js&lt;&#x2F;strong&gt; we will include in &lt;strong&gt;index.html&lt;&#x2F;strong&gt;:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;html&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-html &quot;&gt;&lt;code class=&quot;language-html&quot; data-lang=&quot;html&quot;&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;body&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;div id=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;root&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;gt;&amp;lt;&#x2F;div&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;script src=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;out.js&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;gt;&amp;lt;&#x2F;script&amp;gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;&#x2F;body&amp;gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;And open that file in a browser.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;roadmap&quot;&gt;Roadmap&lt;a class=&quot;zola-anchor&quot; href=&quot;#roadmap&quot; aria-label=&quot;Anchor link for: roadmap&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;In order to achieve the final goal our journey will be splitted into several steps:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;getting familiar with &lt;a href=&quot;https:&#x2F;&#x2F;github.com&#x2F;swc-project&#x2F;swc&quot;&gt;swc&lt;&#x2F;a&gt;&lt;&#x2F;li&gt;
&lt;li&gt;implement Javascript bundler which can bundle our local Javascript files without any external &lt;strong&gt;node_modules&lt;&#x2F;strong&gt; used&lt;&#x2F;li&gt;
&lt;li&gt;add an ability to import &lt;strong&gt;external&lt;&#x2F;strong&gt; packages from &lt;strong&gt;node_modules&lt;&#x2F;strong&gt; folder and bundle all that stuff together&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;h2 id=&quot;initial-setup&quot;&gt;Initial setup&lt;a class=&quot;zola-anchor&quot; href=&quot;#initial-setup&quot; aria-label=&quot;Anchor link for: initial-setup&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Since we are going to run our application as the end user our application will be a binary:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; new&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt; --bin&lt;&#x2F;span&gt;&lt;span&gt; js-bundler
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now let&#x27;s add needed dependencies(&lt;a href=&quot;https:&#x2F;&#x2F;github.com&#x2F;killercup&#x2F;cargo-edit&quot;&gt;cargo add&lt;&#x2F;a&gt; is used here):&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# flexible Results&#x2F;Errors
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add anyhow 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# common swc entities
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add swc_common 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# parsed javascript nodes types
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;carg&lt;&#x2F;span&gt;&lt;span&gt; add swc_ecma_ast 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# transform esmodules to commonjs
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add swc_ecma_codegen
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add swc_ecma_transforms 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# traverse ast
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add swc_ecma_visit 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# generate unique identifiers for modules
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add uuid&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt; --featuers&lt;&#x2F;span&gt;&lt;span&gt; v4
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# store tmp js files for testing
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt; -D&lt;&#x2F;span&gt;&lt;span&gt; tempfile 
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;All project I&#x27;m going to write in one &lt;strong&gt;src&#x2F;main.rs&lt;&#x2F;strong&gt; file.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; all used modules
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;anyhow::Result;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::collections::HashMap;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::collections::HashSet;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::env;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::fs;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::io;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::io::{ErrorKind, Write};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::path::PathBuf;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::rc::Rc;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::sync::Mutex;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;swc_common::{sync::Lrc, Globals, Mark, SourceFile, SourceMap, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;GLOBALS&lt;&#x2F;span&gt;&lt;span&gt;};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;swc_ecma_ast::{
&lt;&#x2F;span&gt;&lt;span&gt;    AssignExpr, CallExpr, Expr, ExprOrSpread, ExprOrSuper, ExprStmt, Ident, Lit, Module,
&lt;&#x2F;span&gt;&lt;span&gt;    ModuleDecl, ModuleItem, Stmt, Str,
&lt;&#x2F;span&gt;&lt;span&gt;};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;swc_ecma_codegen::{text_writer::JsWriter, Emitter};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;swc_ecma_parser::{lexer::Lexer, JscTarget, Parser, StringInput, Syntax};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;swc_ecma_transforms::modules::common_js::common_js;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;swc_ecma_visit::{noop_visit_type, Fold, Node, Visit, VisitWith};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;uuid::Uuid;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;h2 id=&quot;implementation&quot;&gt;Implementation&lt;a class=&quot;zola-anchor&quot; href=&quot;#implementation&quot; aria-label=&quot;Anchor link for: implementation&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Before coding let&#x27;s discuss the main idea which will be used to create a bundler.&lt;br &#x2F;&gt;
While working with Nodejs do you notice that famous &lt;strong&gt;require&lt;&#x2F;strong&gt; function? Basically when we need to import other module we call &lt;strong&gt;require&lt;&#x2F;strong&gt; &lt;strong&gt;function&lt;&#x2F;strong&gt; for that.&lt;br &#x2F;&gt;
The most important part that it&#x27;s a function. And how a functions resolution does work? Ask yourself what will we see in the following scenarios:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; panics in the browser because require is undefined
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; because window.require is undefined
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;foo.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; it&amp;#39;s not important
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; because we&amp;#39;ll lookup from the inside out
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;window&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;require &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;not important&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;function &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;bar&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;foo.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;modules &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;.&#x2F;foo.js&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;: (&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;*module src like*&#x2F;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;exports &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;{a: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;}}};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;bar&lt;&#x2F;span&gt;&lt;span&gt;((&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;{};
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;modules&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;](&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;exports&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;So we can &amp;quot;overwrite&amp;quot; &lt;strong&gt;require&lt;&#x2F;strong&gt; and place there src of the required module. We will do that not exactly the same as in the example above and touch that in more detail in the future. Now our purpose is to understand the basic idea which will be used.&lt;br &#x2F;&gt;
But now is 2020 and I want to write a code with esmodules, not with commonjs.
In order to solve that problem we need to somehow transform our esmodules based code into commonjs based and only after that bundle the project.
And here Bable, swc are used. Since we are in Rust ecosystem swc will be used.&lt;br &#x2F;&gt;
In order to convert esmodule to commonjs module we need to parse file and choose an appropriate strategy into which format we want to convert it.&lt;&#x2F;p&gt;
&lt;p&gt;Let&#x27;s create some test infrastructure. We need to create js files and store them somewhere. For that &lt;strong&gt;tempfile&lt;&#x2F;strong&gt; crate will be used:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cfg&lt;&#x2F;span&gt;&lt;span&gt;(test)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use super&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::fs::read_to_string;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::fs::File;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::io::Write;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::process::Command;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::thread::sleep;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::time::Duration;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;tempfile::{tempdir, TempDir};
&lt;&#x2F;span&gt;&lt;span&gt;	
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;() -&amp;gt; (File, PathBuf, TempDir, String) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; dir &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;tempdir&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;temdir is created&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(file, file_path, name) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file_with_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dir);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        (file, file_path, dir, name)
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;create_tmp_file_with_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;dir&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;TempDir) -&amp;gt; (File, PathBuf, String) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; name &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, Uuid::new_v4().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_hyphenated&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; file_path &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; dir.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;name);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; file &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;File::create(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        (file, file_path, name)
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now we have all needed in order to think about parsing:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;successful_parsing&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file, file_path, dir, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;writeln!&lt;&#x2F;span&gt;&lt;span&gt;(file, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;foo&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; from &amp;#39;.&#x2F;foo.js&amp;#39;;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; parsed_module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_parsed_module&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;init_source_map&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(parsed_module.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_ok&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(parsed_module.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().body.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;As you can I we want to path file path like &lt;code&gt;index.js&lt;&#x2F;code&gt; and receive a parsed module. By parsed I mean the module which is represented by &lt;a href=&quot;https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Abstract_syntax_tree&quot;&gt;AST&lt;&#x2F;a&gt; - basically just a model of our source code represented by Rust building blocks. For curious people - you can print that AST in a neat form and explore it if you want. We will touch that AST in a few minutes.&lt;br &#x2F;&gt;
In order to get parsed module firstly we need to receive a lexer - a tool which knows how to split our code into lexemes. I wrote more about that in &lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox-c-compiler-1&#x2F;&quot;&gt;that post&lt;&#x2F;a&gt;. In order to create a lexer we need to pass it our source code. And only after that we can achieve a parser which can parse a file. Do you see that chain?:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;source -&amp;gt; lexer -&amp;gt; parser -&amp;gt; parsed module&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;So the shape of our function is something like that:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_parsed_module&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;file_path&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;sm&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;Lrc&amp;lt;SourceMap&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Module&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; receiving a source file
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; lf &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;load_file&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;sm.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;())&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; init lexer
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; lexer &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;init_lexer&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;lf);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; init parser
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; parser &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;init_parser&lt;&#x2F;span&gt;&lt;span&gt;(lexer);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    parser
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;parse_module&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map_err&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;| anyhow::Error::msg(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;error during module parsing: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:?}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, e)))
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Let&#x27;s begin from the receiving a source file: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; source map is swc data structure which represents source file
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; (its name, path, number of lines, etc)
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; Lrc it&amp;#39;s swc&amp;#39;s alias to Arc
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;init_source_map&lt;&#x2F;span&gt;&lt;span&gt;() -&amp;gt; Lrc&amp;lt;SourceMap&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Default&lt;&#x2F;span&gt;&lt;span&gt;::default()
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;load_file&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;sm&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;SourceMap, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Lrc&amp;lt;SourceFile&amp;gt;, std::io::Error&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; sm offers api with which we can read a file
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_dir&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we can pass a dir
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; instead of a concrete file
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; in such a case we will lookup for a index.js
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; inside that dir
&lt;&#x2F;span&gt;&lt;span&gt;        sm.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;load_file&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;index.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;))
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; path_as_str &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; path
&lt;&#x2F;span&gt;&lt;span&gt;            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;ok_or&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;pathbuf: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:?}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; to str converted&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;path))
&lt;&#x2F;span&gt;&lt;span&gt;            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map_err&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;| std::io::Error::new(ErrorKind::Other, e))&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if !&lt;&#x2F;span&gt;&lt;span&gt;path_as_str.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;ends_with&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;            sm.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;load_file&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf::from(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, path_as_str)))
&lt;&#x2F;span&gt;&lt;span&gt;        } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            sm.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;load_file&lt;&#x2F;span&gt;&lt;span&gt;(path)
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now lexer initialization - just calling swc factory:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;init_lexer&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;input_file&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a &lt;&#x2F;span&gt;&lt;span&gt;Lrc&amp;lt;SourceFile&amp;gt;) -&amp;gt; Lexer&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;, StringInput&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    Lexer::new(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we are going to parse javascript
&lt;&#x2F;span&gt;&lt;span&gt;        Syntax::Es(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Default&lt;&#x2F;span&gt;&lt;span&gt;::default()),
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; supported standart
&lt;&#x2F;span&gt;&lt;span&gt;        JscTarget::Es2015,
&lt;&#x2F;span&gt;&lt;span&gt;        StringInput::from(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;input_file),
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    )
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;The same with swc parser:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;init_parser&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;lexer&lt;&#x2F;span&gt;&lt;span&gt;: Lexer&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;, StringInput&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;) -&amp;gt; Parser&amp;lt;Lexer&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;, StringInput&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    Parser::new_from(lexer)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now we can run our first test, see that it&#x27;s passed and move on.&lt;br &#x2F;&gt;
With parser we are ready for a transpilation step - transpile ecmamodules to commonjs modules.&lt;&#x2F;p&gt;
&lt;p&gt;This is how we are going to do it - implement a dedicated function for that:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;transpiles_module&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file, file_path, dir, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;writeln!&lt;&#x2F;span&gt;&lt;span&gt;(file, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;foo&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; from &amp;#39;.&#x2F;foo.js&amp;#39;;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; sm &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;init_source_map&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; src &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;js_to_common_js&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_parsed_module&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;sm).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().body, sm);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(src.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_ok&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; u_src &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; src.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;dbg!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;u_src);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        u_src,
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;#&amp;quot;&amp;quot;use strict&amp;quot;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;var _fooJs = require(&amp;quot;.&#x2F;foo.js&amp;quot;);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;#
&lt;&#x2F;span&gt;&lt;span&gt;    )
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;And the implementation:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;js_to_common_js&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ModuleItem&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;sm&lt;&#x2F;span&gt;&lt;span&gt;: Lrc&amp;lt;SourceMap&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; scoped thread-local storage
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; reduces memory usage
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; need to set for swc in order to avoid panic
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;GLOBALS&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;set&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;Globals::new(), || {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; transpiled_module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;transpile_module_to_common_js&lt;&#x2F;span&gt;&lt;span&gt;(module);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; write_to &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; Output(Rc::new(Mutex::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[])));
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;emit_source_code&lt;&#x2F;span&gt;&lt;span&gt;(transpiled_module, sm, write_to.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;())&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; src &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &amp;amp;*&lt;&#x2F;span&gt;&lt;span&gt;write_to.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;lock&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;not poisoned&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(std::str::from_utf8(src)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;    })
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;transpile_module_to_common_js&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ModuleItem&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ModuleItem&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;common_js&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; a mark is a unique id associated with a macro expansion.
&lt;&#x2F;span&gt;&lt;span&gt;        Mark::fresh(Mark::root()),
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; how transform
&lt;&#x2F;span&gt;&lt;span&gt;        swc_ecma_transforms::modules::util::Config {
&lt;&#x2F;span&gt;&lt;span&gt;            no_interop: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;true&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Default&lt;&#x2F;span&gt;&lt;span&gt;::default()
&lt;&#x2F;span&gt;&lt;span&gt;        },
&lt;&#x2F;span&gt;&lt;span&gt;    )
&lt;&#x2F;span&gt;&lt;span&gt;    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;fold_module_items&lt;&#x2F;span&gt;&lt;span&gt;(module)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;emit_source_code&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;W: Write&amp;gt;(
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ModuleItem&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;sm&lt;&#x2F;span&gt;&lt;span&gt;: Lrc&amp;lt;SourceMap&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;writable&lt;&#x2F;span&gt;&lt;span&gt;: W,
&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;()&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    Emitter {
&lt;&#x2F;span&gt;&lt;span&gt;        cfg: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Default&lt;&#x2F;span&gt;&lt;span&gt;::default(),
&lt;&#x2F;span&gt;&lt;span&gt;        cm: sm.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        wr: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;::new(JsWriter::new(sm.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\n&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, writable, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;)),
&lt;&#x2F;span&gt;&lt;span&gt;        comments: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;emit_module&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;Module {
&lt;&#x2F;span&gt;&lt;span&gt;        body: module,
&lt;&#x2F;span&gt;&lt;span&gt;        span: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Default&lt;&#x2F;span&gt;&lt;span&gt;::default(),
&lt;&#x2F;span&gt;&lt;span&gt;        shebang: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    })&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(())
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;The code above is basically an interaction with swc api. It&#x27;s pretty declarative and you can go through it with your IDE and jump, explore if you are curious.
Did you notice that type &lt;strong&gt;Output&lt;&#x2F;strong&gt;? Swc wants to receive something writable, which is behind Lrc(aka Arc) so that I just implemented the following wrapper:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Output&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;W&amp;gt;(Rc&amp;lt;Mutex&amp;lt;W&amp;gt;&amp;gt;);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;W: Write&amp;gt; Write &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Output&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;W&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;write&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;buf&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;u8&lt;&#x2F;span&gt;&lt;span&gt;]) -&amp;gt; io::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;        (&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;lock&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;write&lt;&#x2F;span&gt;&lt;span&gt;(buf)
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;flush&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; io::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;()&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;        (&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;lock&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;flush&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;W: Write&amp;gt; Clone &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Output&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;W&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        Output(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Being able to transpile ecmamodules to commonjs modules now we are ready for modules analyzation step - read module, retrieve info, collect info, transpile it - all needed stuff for continous bundle generation. That new module will be called transformed module(maybe not so good name, anyway).&lt;br &#x2F;&gt;
As usual let&#x27;s begin from the test:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;transforms_module&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file, file_path, dir, name) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file1, file_path1, dir1, name1) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; s &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;foo&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; from &amp;#39;.&#x2F;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;name); &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;&amp;amp;name1
&lt;&#x2F;span&gt;&lt;span&gt;    file.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;write_all&lt;&#x2F;span&gt;&lt;span&gt;(s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_bytes&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;writeln!&lt;&#x2F;span&gt;&lt;span&gt;(file1, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;export const foo = 5;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; sm &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;init_source_map&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; transformed_module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;transform_module&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_parsed_module&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;sm).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().body,
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path,
&lt;&#x2F;span&gt;&lt;span&gt;        sm,
&lt;&#x2F;span&gt;&lt;span&gt;    );
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(transformed_module.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_ok&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; transformed_u_module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; transformed_module.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(transformed_u_module.abs_path, file_path);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(transformed_u_module.imports.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;transformed_u_module.imports[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;].&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..&lt;&#x2F;span&gt;&lt;span&gt;],
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;name
&lt;&#x2F;span&gt;&lt;span&gt;    );
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;It was mentioned before that the transformed module is the module with all needed information for bundling. Let&#x27;s be more precise:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;derive&lt;&#x2F;span&gt;&lt;span&gt;(Debug, Clone)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;ParsedModule &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;id&lt;&#x2F;span&gt;&lt;span&gt;: String,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; abs path to the file
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;abs_path&lt;&#x2F;span&gt;&lt;span&gt;: PathBuf,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; like &amp;quot;.&#x2F;index.js&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;imports&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;PathBuf&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; transpiled js
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;source_code&lt;&#x2F;span&gt;&lt;span&gt;: String,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; import to import module id map
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; such as &amp;quot;.&#x2F;index.js&amp;quot; -&amp;gt; &amp;quot;aoeu-037a-hstp-273s&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;deps_map&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;HashMap&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;I suggest to discuss how the following attributes can be received:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;id -&amp;gt; using Uuid&lt;&#x2F;li&gt;
&lt;li&gt;abs_path -&amp;gt; actually we receive when funtion is called,&lt;&#x2F;li&gt;
&lt;li&gt;source_code -&amp;gt; now we are able to transpile the code&lt;&#x2F;li&gt;
&lt;li&gt;deps_map -&amp;gt; now None. we will fill that in the future(when a modules graph will be traversed)&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;The most interesting and complicated part is how we can receive all &lt;strong&gt;imports&lt;&#x2F;strong&gt;. For doing that swc also will be leveraged. Here we need to know that basically swc offers 2 main things for modules manipulations: traversing and folding. Traverse - it&#x27;s just a passing modules hierarchy and making some conclusions, collecting some info. While folding is about ast manipulations&#x2F;modifications. Since we need only to collect the data - visiting facilities will be used.
For doing that firstly we need to implement trait Visit: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;ImportsTraverser &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;imports&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl &lt;&#x2F;span&gt;&lt;span&gt;Visit &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;ImportsTraverser &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; use defaults traverses for not implemented traverse types from our side
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; since we are interesting only in those where imports can be present.
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;noop_visit_type!&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; So every type of ast has a dediacted traverser
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we receive its root and can pattern match against things 
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; in which we are interested in
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;visit_module_decl&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;n&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;ModuleDecl, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_parent&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dyn Node) {
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; n {
&lt;&#x2F;span&gt;&lt;span&gt;           &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; just pattern match against ast node type we are interested in
&lt;&#x2F;span&gt;&lt;span&gt;           &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; I found that type just by exploring tha produced ast from tests
&lt;&#x2F;span&gt;&lt;span&gt;           ModuleDecl::Import(decl) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.imports.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(decl.src.value.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;()),
&lt;&#x2F;span&gt;&lt;span&gt;           &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;       }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; do our stuff but continue traversing
&lt;&#x2F;span&gt;&lt;span&gt;       n.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;visit_children_with&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;   }
&lt;&#x2F;span&gt;&lt;span&gt;   
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;visit_module_item&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;n&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;ModuleItem, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_parent&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dyn Node) {
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; n {
&lt;&#x2F;span&gt;&lt;span&gt;           ModuleItem::ModuleDecl(ModuleDecl::Import(decl)) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;               &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.imports.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(decl.src.value.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;           }
&lt;&#x2F;span&gt;&lt;span&gt;           &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;       }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;       n.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;visit_children_with&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;   }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Since our intermediate goal is to make possible to run esmodules based code that&#x27;s enough. In future when we needed to use packages from node_modules additional things will be added(since node_modules are commonjs based, but not esmodules based).&lt;&#x2F;p&gt;
&lt;p&gt;And now we have all needed in order to implement the &lt;code&gt;transform_module&lt;&#x2F;code&gt; function itself:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;transform_module&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;items&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ModuleItem&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;path_to_module&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf,
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;sm&lt;&#x2F;span&gt;&lt;span&gt;: Lrc&amp;lt;SourceMap&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; imports: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;PathBuf&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; items
&lt;&#x2F;span&gt;&lt;span&gt;       .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;       .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;m&lt;&#x2F;span&gt;&lt;span&gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;           &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; t &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; ImportsTraverser { imports: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[] };
&lt;&#x2F;span&gt;&lt;span&gt;           m.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;visit_with&lt;&#x2F;span&gt;&lt;span&gt;(m, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; t);
&lt;&#x2F;span&gt;&lt;span&gt;           t.imports
&lt;&#x2F;span&gt;&lt;span&gt;       })
&lt;&#x2F;span&gt;&lt;span&gt;       .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;flatten&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;       .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(PathBuf::from)
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; filter for repeated imports
&lt;&#x2F;span&gt;&lt;span&gt;       .collect::&amp;lt;HashSet&amp;lt;PathBuf&amp;gt;&amp;gt;()
&lt;&#x2F;span&gt;&lt;span&gt;       .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;       .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(PathBuf::from)
&lt;&#x2F;span&gt;&lt;span&gt;       .collect::&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;PathBuf&amp;gt;&amp;gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(ParsedModule {
&lt;&#x2F;span&gt;&lt;span&gt;       id: Uuid::new_v4().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_hyphenated&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;       abs_path: path_to_module.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;       imports,
&lt;&#x2F;span&gt;&lt;span&gt;       source_code: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;js_to_common_js&lt;&#x2F;span&gt;&lt;span&gt;(items.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(), sm)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; will be set in the future as it was mentioned
&lt;&#x2F;span&gt;&lt;span&gt;       deps_map: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;   })
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;After tha &lt;code&gt;transforms_module&lt;&#x2F;code&gt; test should be green and we are moving on.
We are able to parse the module, now we can implement the modules hierarchy builder.
Another test for it:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;builds_deps_hierarchy&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file, file_path, dir, name) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file1, file_path1, name1) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file_at_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dir);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; s &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;foo&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; from &amp;#39;.&#x2F;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;name1); &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;&amp;amp;name1
&lt;&#x2F;span&gt;&lt;span&gt;    file.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;write_all&lt;&#x2F;span&gt;&lt;span&gt;(s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_bytes&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;writeln!&lt;&#x2F;span&gt;&lt;span&gt;(file1, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;export const foo = 5;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; root_with_deps_top_down &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_deps_tree&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(root_with_deps_top_down.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_ok&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; u_root_with_deps_top_down &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; root_with_deps_top_down.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;dbg!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;u_root_with_deps_top_down);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(u_root_with_deps_top_down.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(u_root_with_deps_top_down[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;].abs_path, file_path1);
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;We expect that &lt;code&gt;create_deps_tree&lt;&#x2F;code&gt; will give us all needed modules aka files which are used with the root at first position. Basically those are independent in the sense that every module can be treated individually. Bundler is only interested in the root module because it&#x27;s the module from which a bundling process bootstraps.
In order to get all transformed modules we need to do a top down traverse. We get the root module, check its imports and push them into a traverse queue. Then the dependencies of those imports. And so on and so on.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;create_deps_tree&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;root&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; parsed_root &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_transformed_module&lt;&#x2F;span&gt;&lt;span&gt;(root)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; tmp comment
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we&amp;#39;ll go back to it in a few minutes
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; let node_modules = scan_node_modules();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; node_modules &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;HashSet::new();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; transformed_modules: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[parsed_root.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;()];
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; modules_to_traverse: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[parsed_root];
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; cache: HashMap&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, ParsedModule&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;HashMap::new();
&lt;&#x2F;span&gt;&lt;span&gt;    
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; let&amp;#39;s cache created modules and use them instead of creating duplicates
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; cache: HashMap&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, ParsedModule&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;HashMap::new();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;while !&lt;&#x2F;span&gt;&lt;span&gt;modules_to_traverse.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_empty&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; new_modules &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for&lt;&#x2F;span&gt;&lt;span&gt; module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;in&lt;&#x2F;span&gt;&lt;span&gt; modules_to_traverse.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter_mut&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for&lt;&#x2F;span&gt;&lt;span&gt; dep &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;in&lt;&#x2F;span&gt;&lt;span&gt; module.imports.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; dependency_path &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_dependency_path&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dep, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;module.abs_path, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;node_modules)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; if in cache -&amp;gt; use already transformed module
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; else evaluate and cache
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; dep_info &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; cache.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;contains_key&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dependency_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;()) {
&lt;&#x2F;span&gt;&lt;span&gt;                        cache
&lt;&#x2F;span&gt;&lt;span&gt;                            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dependency_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;                            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; dep_info &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_transformed_module&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dependency_path)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;                        cache.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;insert&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;                            dep_info.abs_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                            dep_info.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                        );
&lt;&#x2F;span&gt;&lt;span&gt;                        new_modules.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(dep_info.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;                        dep_info
&lt;&#x2F;span&gt;&lt;span&gt;                    };
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; probably HashMap can be used instead
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; m &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; transformed_modules
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter_mut&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;find&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;item&lt;&#x2F;span&gt;&lt;span&gt;| item.id &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;==&lt;&#x2F;span&gt;&lt;span&gt; module.id)
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;module is present&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; m.deps_map.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_none&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                    m.deps_map &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(std::collections::HashMap::new());
&lt;&#x2F;span&gt;&lt;span&gt;                }
&lt;&#x2F;span&gt;&lt;span&gt;                m.deps_map.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_mut&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;insert&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;                    dep.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;converted&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                    dep_info.id.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                );
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;        transformed_modules.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;append&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; new_modules.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_iter&lt;&#x2F;span&gt;&lt;span&gt;().collect::&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;());
&lt;&#x2F;span&gt;&lt;span&gt;        modules_to_traverse &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; new_modules.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_iter&lt;&#x2F;span&gt;&lt;span&gt;().collect::&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt;&amp;gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(transformed_modules)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Well, that one a little big. Probably it&#x27;s time to think about some &lt;strong&gt;Bundler&lt;&#x2F;strong&gt; struct and split that into multiple functions. But I&#x27;ll move one.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_dependency_path&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;dep_relative_root_path&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;parent_abs_path&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;node_modules&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;HashSet&amp;lt;PathBuf&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;PathBuf&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; dep_relative_root_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_absolute&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Err&lt;&#x2F;span&gt;&lt;span&gt;(anyhow::Error::msg(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;doesn&amp;#39;t work with absolute paths&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        ))
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; node_modules related
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; will touch it in a few minutes
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; if starts_from(&amp;amp;dep_relative_root_path, &amp;amp;node_modules) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;    Ok(PathBuf::from(&amp;quot;node_modules&amp;quot;).join(dep_relative_root_path))
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; } else {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; file_name &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dep_relative_root_path
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;ok_or&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;pathbuf: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:?}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; to str converted&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dep_relative_root_path
&lt;&#x2F;span&gt;&lt;span&gt;                ))
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map_err&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;| anyhow::Error::msg(e))&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..&lt;&#x2F;span&gt;&lt;span&gt;];
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; parent_abs_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_dir&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(parent_abs_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name))
&lt;&#x2F;span&gt;&lt;span&gt;            } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; dir &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_path_to_file_parent_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;parent_abs_path);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(dir.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name))
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now we should see that our &lt;code&gt;builds_deps_hierarchy&lt;&#x2F;code&gt; should pass.&lt;br &#x2F;&gt;
Finally we can begin to write the code for bundling:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;generates_bundle_code&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file, file_path, dir, name) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; file1, file_path1, name1) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_tmp_file_at_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dir);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; s &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;foo&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; from &amp;#39;.&#x2F;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;console.log(foo)&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;name1
&lt;&#x2F;span&gt;&lt;span&gt;    );
&lt;&#x2F;span&gt;&lt;span&gt;    file.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;write_all&lt;&#x2F;span&gt;&lt;span&gt;(s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_bytes&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;writeln!&lt;&#x2F;span&gt;&lt;span&gt;(file1, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;export const foo = 5;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; src &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;generate_bundle&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_deps_tree&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_path).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; bundle &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;File::create(dir.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;bundle.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;bundle.js created&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    bundle
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;write_all&lt;&#x2F;span&gt;&lt;span&gt;(src.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_bytes&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;bundle has written&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; stderr_path &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; dir.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;stderr&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; cmd &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Command::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;node&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; child &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; cmd
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;args&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;bundle.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;])
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;current_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dir)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;stdout&lt;&#x2F;span&gt;&lt;span&gt;(File::create(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;stderr_path).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;spawn&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;bundle execution started&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;sleep&lt;&#x2F;span&gt;&lt;span&gt;(Duration::from_secs(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;));
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; content &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=
&lt;&#x2F;span&gt;&lt;span&gt;        std::fs::read_to_string(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;stderr_path).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;unable to read from stderr file&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(content, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;5&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\n&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;The test bundles files into one module and tries to run it with Node.js. We subscribe on its stdout so that we can collect it and match against expected values.&lt;&#x2F;p&gt;
&lt;p&gt;Now let&#x27;s discuss how we are going to generate the resulted bundle in more detail. We already saw the idea how we can leverage &lt;code&gt;require&lt;&#x2F;code&gt; for our goal. Also we already know that we need to start from the root module. Basically we can split our bundle into 3 parts: creating a specific &lt;code&gt;require&lt;&#x2F;code&gt; function, passing modules and bootstraping.&lt;&#x2F;p&gt;
&lt;p&gt;Firstly let&#x27;s take a look at how our passed modules will be looked like: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;8e840584-99d7-413a-abb1-867357953d0d&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;: {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;wrapped_module&lt;&#x2F;span&gt;&lt;span&gt;: (&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;exports&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;      &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;use strict&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;      &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;var &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_index2Js &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index2.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;      &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;var &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_index3Js &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index3.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;      &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;console&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;log&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_index2Js&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_index3Js&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    },
&lt;&#x2F;span&gt;&lt;span&gt;    deps_map: {
&lt;&#x2F;span&gt;&lt;span&gt;      &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index3.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;8be36e6a-eeb7-4ce4-8b11-040d6c8e8987&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;      &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index2.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;1edc9be4-e93e-4e79-bb16-0d5ec19f3255&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    },
&lt;&#x2F;span&gt;&lt;span&gt;  },
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; ...other_modules
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;So you can see that it contains from the actual module code + its dependencies.&lt;&#x2F;p&gt;
&lt;p&gt;Now let&#x27;s take a look on &lt;code&gt;require&lt;&#x2F;code&gt; function:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;require &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;id &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we have an access to all modules via `modules` var
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; so that we fetch needed module&amp;#39;s data
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;wrapped_module&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;deps_map&lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;modules&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;id&lt;&#x2F;span&gt;&lt;span&gt;];
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; create a special unique require function for a particular require call
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;localRequire &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;requiredModuleName &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;deps_map&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;requiredModuleName&lt;&#x2F;span&gt;&lt;span&gt;]);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; every require has its own scope
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;{exports: {}};
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; probably we can do: wrapped_module(module, module.exports, localRequire)
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; but wepback does differently
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; so that the context is correct
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; module.exports and exports are passed
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; because in the code we can write
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; module.exports = {};
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; and
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; exports = {};
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; it&amp;#39;s related to node_modules
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;wrapped_module&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;call&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;exports&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;exports&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;localRequire&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;exports&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;With that when we are writing: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; bar === exports
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;foo.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;require is a function call. It receives a dependency name. Based on that we fetch needed function module(wrapped code + its dependencies). After that we prepare a clean modules object and make a wrapped_module wrapper. After that call our &lt;strong&gt;module&lt;&#x2F;strong&gt; export variable will be filled by all exports from the module and finally our &lt;strong&gt;bar&lt;&#x2F;strong&gt; variable will be with the value. But that&#x27;s the case when &amp;quot;.&#x2F;foo.js&amp;quot; doesn&#x27;t contain dependencies. If it does we will execute them. And so on and so forth. When all leaves are executed the same - we will receive from bottom to top our &lt;strong&gt;module&lt;&#x2F;strong&gt; exports.&lt;&#x2F;p&gt;
&lt;p&gt;I think that we&#x27;ve discussed how it works. Now we only need to write the code:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;generate_bundle&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;modules_hierarchy&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt;) -&amp;gt; String {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; transformed modules to module&amp;#39;s form
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; which we just discussed
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; modules_executables: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; modules_hierarchy
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;module&lt;&#x2F;span&gt;&lt;span&gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; module_deps &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; dependent module should be serialized 
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; into javascript object(Rust HashMap -&amp;gt; Js object)
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; if it&amp;#39;s present
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(map) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;module.deps_map.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_ref&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                    serde_json::to_string(map).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;deps map into json serialized&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;                } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;{}&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_owned&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                }
&lt;&#x2F;span&gt;&lt;span&gt;            };
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\&amp;quot;{module_id}\&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;              factory: (module, exports, require) =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{module_source_code}
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;              &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;,
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;              map: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{module_deps}
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;	    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;                module_id &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;module.id,
&lt;&#x2F;span&gt;&lt;span&gt;                module_source_code &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; module.source_code,
&lt;&#x2F;span&gt;&lt;span&gt;                module_deps &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; module_deps
&lt;&#x2F;span&gt;&lt;span&gt;            )
&lt;&#x2F;span&gt;&lt;span&gt;        })
&lt;&#x2F;span&gt;&lt;span&gt;        .collect::&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;,&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; bundler_core &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;(function(modules)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;    const require = id =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;factory, map&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; = modules[id];
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      const localRequire = requireDeclarationName =&amp;gt; require(map[requireDeclarationName]);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      const module = &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;exports: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{}}}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      factory.call(module.exports, module, module.exports, localRequire);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      return module.exports;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;    require(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\&amp;quot;{root_module_id}\&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;)(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{ {modules} }}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;)
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;        root_module_id &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; modules_hierarchy.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;source root is present&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).id,
&lt;&#x2F;span&gt;&lt;span&gt;        modules &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; modules_executables
&lt;&#x2F;span&gt;&lt;span&gt;    );
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    bundler_core
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;After that the test &lt;code&gt;generates_bundle_code&lt;&#x2F;code&gt; should be green. &lt;&#x2F;p&gt;
&lt;p&gt;For playing with that as a bin application let&#x27;s write the main function:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;main&lt;&#x2F;span&gt;&lt;span&gt;() -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;()&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; args: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;env::args().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(entry) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; args.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; root_with_deps_top_down &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;create_deps_tree&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf::from(entry));
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; u_root_with_deps_top_down &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; root_with_deps_top_down.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; src &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;generate_bundle&lt;&#x2F;span&gt;&lt;span&gt;(u_root_with_deps_top_down);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        std::fs::write(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;out.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, src)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(())
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Err&lt;&#x2F;span&gt;&lt;span&gt;(anyhow::Error::msg(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;entry point should be provided&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        ))
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;I suggest to create a test dir for our tries.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; src
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;mkdir&lt;&#x2F;span&gt;&lt;span&gt; test
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; test
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now index.js&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span&gt;{ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index2.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span&gt;{ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index3.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;baz &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;index4.js&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;console&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;log&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;baz&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;index2.js:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;export &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;index3.js&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;export &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;5&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;index4.js&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;js&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-js &quot;&gt;&lt;code class=&quot;language-js&quot; data-lang=&quot;js&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span&gt;{ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;.&#x2F;index2.js&amp;#39; 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;import &lt;&#x2F;span&gt;&lt;span&gt;{ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;.&#x2F;index3.js&amp;#39; 
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;baz &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;foo &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;bar&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;export default &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;baz&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Finally:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; run index.js
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;node&lt;&#x2F;span&gt;&lt;span&gt; out.js
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;&#x2F;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt; 14
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;And congrats!! We&#x27;ve created a bundler which can bundle our local project! Let&#x27;s take a rest a bit...&lt;&#x2F;p&gt;
&lt;p&gt;But real projects are consisted from not only our own code but as well as external code. So it would be cute if we can to use external packages as well.&lt;br &#x2F;&gt;
Let&#x27;s do it.&lt;&#x2F;p&gt;
&lt;p&gt;And I have good news - we need to add not so many lines.&lt;&#x2F;p&gt;
&lt;p&gt;The first thing which should be added is traversing cases. Node modules are commonjs based, but not esmodules based. So it means that our code just won&#x27;t compile.&lt;&#x2F;p&gt;
&lt;p&gt;The idea is following. We can meet &lt;strong&gt;require&lt;&#x2F;strong&gt; in many places and we need to cover tham. I just played with compiling and AST exploration in order to find them. So that I can&#x27;t not guarantee that all cases are covered.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;ImportsTraverser &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; matcher for require
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;match_require&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;sym&lt;&#x2F;span&gt;&lt;span&gt;: String, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;args&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ExprOrSpread&amp;gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; sym.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;() &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;== &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;require&amp;quot; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; args.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;() &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;== &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1 &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match &amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;args[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;] {
&lt;&#x2F;span&gt;&lt;span&gt;                    ExprOrSpread { expr, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match &amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;expr {
&lt;&#x2F;span&gt;&lt;span&gt;                        Expr::Lit(Lit::Str(Str { value, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;})) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.imports.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(value.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;                        }
&lt;&#x2F;span&gt;&lt;span&gt;                        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                    },
&lt;&#x2F;span&gt;&lt;span&gt;                }
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl &lt;&#x2F;span&gt;&lt;span&gt;Visit &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;ImportsTraverser &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; ... previously added stuff
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;visit_module_item&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;n&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;ModuleItem, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_parent&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dyn Node) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; n {
&lt;&#x2F;span&gt;&lt;span&gt;            ModuleItem::Stmt(Stmt::Expr(ExprStmt { expr, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;})) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match &amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;expr {
&lt;&#x2F;span&gt;&lt;span&gt;                    Expr::Call(CallExpr { callee, args, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;}) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match&lt;&#x2F;span&gt;&lt;span&gt; callee {
&lt;&#x2F;span&gt;&lt;span&gt;                        ExprOrSuper::Expr(i) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match &amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;i {
&lt;&#x2F;span&gt;&lt;span&gt;                            Expr::Ident(Ident { sym, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;}) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;match_require&lt;&#x2F;span&gt;&lt;span&gt;(sym.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(), args);
&lt;&#x2F;span&gt;&lt;span&gt;                            }
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                        },
&lt;&#x2F;span&gt;&lt;span&gt;                        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                    },
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                }
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;            ModuleItem::ModuleDecl(ModuleDecl::Import(decl)) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.imports.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(decl.src.value.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        n.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;visit_children_with&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;visit_call_expr&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;n&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;CallExpr, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_parent&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dyn Node) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; n {
&lt;&#x2F;span&gt;&lt;span&gt;            CallExpr { callee, args, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match&lt;&#x2F;span&gt;&lt;span&gt; callee {
&lt;&#x2F;span&gt;&lt;span&gt;                ExprOrSuper::Expr(i) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match &amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;i {
&lt;&#x2F;span&gt;&lt;span&gt;                    Expr::Ident(Ident { sym, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;}) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;match_require&lt;&#x2F;span&gt;&lt;span&gt;(sym.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(), args);
&lt;&#x2F;span&gt;&lt;span&gt;                    }
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                },
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;            },
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        n.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;visit_children_with&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;visit_assign_expr&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;n&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;AssignExpr, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;_parent&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dyn Node) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; n {
&lt;&#x2F;span&gt;&lt;span&gt;            AssignExpr { right, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match &amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;right {
&lt;&#x2F;span&gt;&lt;span&gt;                Expr::Call(CallExpr { callee, args, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;}) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match&lt;&#x2F;span&gt;&lt;span&gt; callee {
&lt;&#x2F;span&gt;&lt;span&gt;                    ExprOrSuper::Expr(i) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; match &amp;amp;**&lt;&#x2F;span&gt;&lt;span&gt;i {
&lt;&#x2F;span&gt;&lt;span&gt;                        Expr::Ident(Ident { sym, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;.. &lt;&#x2F;span&gt;&lt;span&gt;}) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;match_require&lt;&#x2F;span&gt;&lt;span&gt;(sym.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(), args);
&lt;&#x2F;span&gt;&lt;span&gt;                        }
&lt;&#x2F;span&gt;&lt;span&gt;                        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                    },
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                },
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;            },
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        n.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;visit_children_with&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;create_deps_tree&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;root&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; ...
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; do you remember this line?
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; now we are ready to implement that function
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; the basic idea behind it is
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; when we encounter in the require something like
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; require(&amp;#39;react&amp;#39;)
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we should ask whether it&amp;#39;s node_modules package
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; let node_modules = scan_node_modules();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; ...
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;scan_node_modules&lt;&#x2F;span&gt;&lt;span&gt;() -&amp;gt; HashSet&amp;lt;PathBuf&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(entries) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;read_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;node_modules&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;        HashSet::from(
&lt;&#x2F;span&gt;&lt;span&gt;            entries
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;                    PathBuf::from(
&lt;&#x2F;span&gt;&lt;span&gt;                        e.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;entry&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;                            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;path&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;strip_prefix&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;node_modules&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;                            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;node_modules prefix stripped&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                    )
&lt;&#x2F;span&gt;&lt;span&gt;                })
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        )
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        HashSet::new()
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now we can uncomment the code which is responsibe for that lookup. The idea behind a lookup now is a pretty straightforward - we try to find in the root(where entry is placed) &lt;strong&gt;node_modules&lt;&#x2F;strong&gt; dir with the import name. And there index.js. BTW it could not only be index.js, other entry point can be specified via package.json. But for our case it&#x27;s enough as well as only one, near the entry point, node_modules lookup.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_dependency_path&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;dep_relative_root_path&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;parent_abs_path&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;PathBuf,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;node_modules&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;HashSet&amp;lt;PathBuf&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;PathBuf&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; dep_relative_root_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_absolute&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Err&lt;&#x2F;span&gt;&lt;span&gt;(anyhow::Error::msg(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;doesn&amp;#39;t work with absolute paths&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        ))
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; node_modules related
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; will touch it in a few minutes
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; if starts_from(&amp;amp;dep_relative_root_path, &amp;amp;node_modules) {
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;    Ok(PathBuf::from(&amp;quot;node_modules&amp;quot;).join(dep_relative_root_path))
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; } else {
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; so now if it&amp;#39;s a node package we will generate a path to it
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+        if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;starts_from&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dep_relative_root_path, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;node_modules) {
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(PathBuf::from(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;node_modules&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(dep_relative_root_path))
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+        &lt;&#x2F;span&gt;&lt;span&gt;} &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; file_name &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dep_relative_root_path
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_str&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;ok_or&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;pathbuf: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:?}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; to str converted&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;dep_relative_root_path
&lt;&#x2F;span&gt;&lt;span&gt;                ))
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map_err&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;| anyhow::Error::msg(e))&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..&lt;&#x2F;span&gt;&lt;span&gt;];
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; parent_abs_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_dir&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(parent_abs_path.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name))
&lt;&#x2F;span&gt;&lt;span&gt;            } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; dir &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_path_to_file_parent_dir&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;parent_abs_path);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(dir.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;join&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name))
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; }
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+        &lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;And finally, one more thing. While building a react it looks for env variable in order to understand whether prod or dev build is needed.&lt;br &#x2F;&gt;
So:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;generate_bundle&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;modules_hierarchy&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ParsedModule&amp;gt;) -&amp;gt; String {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; ...other stuff
&lt;&#x2F;span&gt;&lt;span&gt;    
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; bundler_core &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;(function(modules)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;     &#x2F;&#x2F; we inject a static env variable into the bundle
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;+    if (typeof window !== &amp;#39;undefined&amp;#39;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;+    window.process = &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;env: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;NODE_ENV: &amp;#39;production&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;    const require = id =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      const &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;wrapped_module, deps_map&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; = modules[id];
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      const localRequire = requiredModuleName =&amp;gt; require(deps_map[requiredModuleName]);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      const module = &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;exports: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{}}}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      wrapped_module.call(module.exports, module, module.exports, localRequire);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;      return module.exports;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;    require(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\&amp;quot;{root_module_id}\&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;);
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;}}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;)(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{{ {modules} }}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;)
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;        root_module_id &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; modules_hierarchy.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;source root is present&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).id,
&lt;&#x2F;span&gt;&lt;span&gt;        modules &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; modules_executables
&lt;&#x2F;span&gt;&lt;span&gt;    );
&lt;&#x2F;span&gt;&lt;span&gt;    
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; ...other stuff
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;And that&#x27;s it!&lt;&#x2F;p&gt;
&lt;p&gt;Now we can bootstrap &lt;strong&gt;React hello world&lt;&#x2F;strong&gt; from the beginning:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# src&#x2F;test
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;npm&lt;&#x2F;span&gt;&lt;span&gt; i
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;npm&lt;&#x2F;span&gt;&lt;span&gt; add react react-dom
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;test&#x2F;index.js
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;* as&lt;&#x2F;span&gt;&lt;span&gt; React from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;react&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;import &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;* as&lt;&#x2F;span&gt;&lt;span&gt; ReactDOM from &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;react-dom&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;class Hello extends React.Component {
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;render&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return&lt;&#x2F;span&gt;&lt;span&gt; React.createElement(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;div&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, null, `Hello &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt;{this.props.toWhat}`);
&lt;&#x2F;span&gt;&lt;span&gt;  }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;ReactDOM.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;render&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;  React.createElement(Hello, { toWhat: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;World&amp;quot; &lt;&#x2F;span&gt;&lt;span&gt;}, null),
&lt;&#x2F;span&gt;&lt;span&gt;  document.getElementById(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;root&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;html&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-html &quot;&gt;&lt;code class=&quot;language-html&quot; data-lang=&quot;html&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&amp;lt;!-- src&#x2F;test&#x2F;index.html --&amp;gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;body&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;&amp;lt;noscript&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;You need to enable JavaScript to run this app.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;&amp;lt;&#x2F;noscript&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;div id=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;root&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;gt;&amp;lt;&#x2F;div&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;script src=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;out.js&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;gt;&amp;lt;&#x2F;script&amp;gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;&amp;lt;&#x2F;body&amp;gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; run index.js
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;hello_world_react_js_bundler.png&quot; alt=&quot;hello_world_react_with_js_bundler&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;h1 id=&quot;performance-not-objective-could-be-skipped&quot;&gt;Performance(not objective, could be skipped)&lt;a class=&quot;zola-anchor&quot; href=&quot;#performance-not-objective-could-be-skipped&quot; aria-label=&quot;Anchor link for: performance-not-objective-could-be-skipped&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h1&gt;
&lt;p&gt;And a little comparison with webpack(I understand that it&#x27;s incorrect to compare solutions because webpack is a more wider thing. But with its out of the box configuration I think that it will be at least interesting =)):&lt;&#x2F;p&gt;
&lt;p&gt;Webpack with default config:&lt;&#x2F;p&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;js_bundle_time_webpack.png&quot; alt=&quot;js_bundle_time_webpack&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;Our bundler compiled in a release mode:
&lt;img src=&quot;..&#x2F;js_bundle_time_rust.png&quot; alt=&quot;js_bundle_time_rust&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;BTW I think it would be interesting to utilize threads for modules transformations.&lt;&#x2F;p&gt;
&lt;h1 id=&quot;afterwords&quot;&gt;Afterwords&lt;a class=&quot;zola-anchor&quot; href=&quot;#afterwords&quot; aria-label=&quot;Anchor link for: afterwords&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h1&gt;
&lt;p&gt;While writing that post I could missed something(logically or from the original source).
So for those who are curious the working version can be found here: &lt;a href=&quot;https:&#x2F;&#x2F;github.com&#x2F;kakoc&#x2F;myox_js_bundler&quot;&gt;repo&lt;&#x2F;a&gt;.&lt;&#x2F;p&gt;
&lt;p&gt;I hope that it was useful and you enjoyed that post.&lt;&#x2F;p&gt;
</description>
      </item>
      <item>
          <title>MYOX: Youtube downloader</title>
          <pubDate>Wed, 07 Oct 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox-youtube-downloader/</link>
          <guid>https://kakoc.blog/blog/myox-youtube-downloader/</guid>
          <description>&lt;p&gt;&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox&#x2F;&quot;&gt;MYOX: what does it mean?&lt;&#x2F;a&gt;&lt;&#x2F;p&gt;
&lt;h2 id=&quot;preface&quot;&gt;Preface&lt;a class=&quot;zola-anchor&quot; href=&quot;#preface&quot; aria-label=&quot;Anchor link for: preface&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;While walking, training, going to work I like to listen to various talks, podcasts, etc. Recently I decided to save a couple of them on my phone. I found some web apps which allowed me to do that. But there were some many ads, it was so unpleasant to deal with them. This is why started to looking for a way how I can do that on my own, without intermediate services. And as you will see in a few minutes it&#x27;s easy to do.&lt;&#x2F;p&gt;
&lt;p&gt;I will show how to implement a trivial downloader(a possibility to dynamically select a resolution, download only audio tracks - their implementation is trivial and you will be able to implement it on your own, as an excercise if you will).&lt;&#x2F;p&gt;
&lt;h2 id=&quot;implementation&quot;&gt;Implementation&lt;a class=&quot;zola-anchor&quot; href=&quot;#implementation&quot; aria-label=&quot;Anchor link for: implementation&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;It will be a binary create since we are going to use it as a usual application.
My intention is to run it as:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;.&#x2F;youtube-downloader&lt;&#x2F;span&gt;&lt;span&gt; https:&#x2F;&#x2F;www.youtube.com&#x2F;watch&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;v=Bn40gUUd5m0
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Lets create a project(in order to add packages I&#x27;ll use &lt;a href=&quot;https:&#x2F;&#x2F;github.com&#x2F;killercup&#x2F;cargo-edit&quot;&gt;cargo add&lt;&#x2F;a&gt;):&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; new youtube-downloader
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; youtube-downloader
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# flexible Results&#x2F;Errors
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add anyhow 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# parse id
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add regex 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# network requests
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add reqwest&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt; --features&lt;&#x2F;span&gt;&lt;span&gt; blocking
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# traverse querystring
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add qstring 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# payload deserialization
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add serde_json 
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;All stuff will be placed in one ~main.rs~ file.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;anyhow::Result;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;qstring::QString;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;reqwest::{blocking::Client, Url};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;serde_json::Value;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; read the passed by a user link
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::env;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Firstly we need to fetch an id from link which a user passed. Lets begin from a test:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cfg&lt;&#x2F;span&gt;&lt;span&gt;(test)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;tests &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use super&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_id_from_url_extraction_short&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=Bn40gUUd5m0&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; id &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_id&lt;&#x2F;span&gt;&lt;span&gt;(url);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(id.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_some&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(id.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;Bn40gUUd5m0&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;As you can see the video id is placed behind ~?v=~.
We won&#x27;t be very attentive, such as handling extended with params, but valid links.&lt;&#x2F;p&gt;
&lt;p&gt;Implementation:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_video_id&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;url&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(id) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;regex::Regex::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;https:&#x2F;&#x2F;www\.youtube\.com&#x2F;watch\?v=(.*)&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;correct regex&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;captures&lt;&#x2F;span&gt;&lt;span&gt;(url)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;    {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(id.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now when we have the video id we can ask youtube to give us an info about that video file. We can do that via the special api endpoint which youtube provides.
A simple test just to be sure that something was fetched:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;   #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_get_video_info&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=zCLOJ9j1k2Y&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; info &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_info&lt;&#x2F;span&gt;&lt;span&gt;(url);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;       &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(info.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_ok&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;   }
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_video_info&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;url&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Value&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; json &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(id) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_id&lt;&#x2F;span&gt;&lt;span&gt;(url) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; video_url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;https:&#x2F;&#x2F;www.youtube.com&#x2F;get_video_info?video_id=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;amp;el=embedded&amp;amp;ps=default&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;            id
&lt;&#x2F;span&gt;&lt;span&gt;        );
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; res_body &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;reqwest::blocking::get(video_url.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;())&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;text&lt;&#x2F;span&gt;&lt;span&gt;()&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        QString::from(res_body.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;player_response&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap_or&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;            .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_owned&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Err&lt;&#x2F;span&gt;&lt;span&gt;(anyhow::Error::msg(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;couldn&amp;#39;t get video id&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;()));
&lt;&#x2F;span&gt;&lt;span&gt;    };
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(serde_json::from_str(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;json)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Explanation: we fetch the video info via the special endpoint. After that we are trying to find &lt;strong&gt;player_response&lt;&#x2F;strong&gt; part from query string. The placed there value is json, so if it&#x27;s present we try to parse it. I encourage you to explore that parsed object.&lt;br &#x2F;&gt;
In the parsed object there is a lot of information. We are interesting in &lt;strong&gt;video_info[&amp;quot;streamingData&amp;quot;][&amp;quot;formats&amp;quot;]&lt;&#x2F;strong&gt;. There we can find various video formats with their metainfo. Also there is &lt;strong&gt;video_info[&amp;quot;streamingData&amp;quot;][&amp;quot;adaptiveFormats&amp;quot;]&lt;&#x2F;strong&gt; part where you can find even more available to download formats. All those objects have a field &lt;strong&gt;url&lt;&#x2F;strong&gt; which describes the actual place from which we can extract the video. We will focus on &lt;strong&gt;video_info[&amp;quot;streamingData&amp;quot;][&amp;quot;formats&amp;quot;]&lt;&#x2F;strong&gt; since it&#x27;s more simple and it&#x27;s ok for this tutorial.&lt;br &#x2F;&gt;
So lets move on implement a function which should give us an actual download link. As I said earlier we won&#x27;t dig into dynamic video quality configuration, just download the most simple one.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_get_video_download_url&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=zCLOJ9j1k2Y&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; video_info &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_info&lt;&#x2F;span&gt;&lt;span&gt;(url).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_download_url&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;video_info);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(url.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_some&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_video_download_url&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;video_info&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;serde_json::Value) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; since there are many formats and their codec we are going to download the post popular
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; mp4_codec_regex &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;regex::Regex::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;codecs=(.*mp4.*)&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;correct codecs regexp&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for&lt;&#x2F;span&gt;&lt;span&gt; t &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;in&lt;&#x2F;span&gt;&lt;span&gt; video_info[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;streamingData&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;][&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;formats&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;].&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_array&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;	    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; so that we can check the appropriate needed video quality
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;360p&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; t[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;qualityLabel&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;].&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if&lt;&#x2F;span&gt;&lt;span&gt; mp4_codec_regex
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;find&lt;&#x2F;span&gt;&lt;span&gt;(t[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;mimeType&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;].&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_some&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;            {
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(t[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;url&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;].&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now, when we can fetch the actual link to the file we can try to download it. I will write a simple test just to not run an app manually if something was wrong.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_file_download&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=Bn40gUUd5m0&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; video_info &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_info&lt;&#x2F;span&gt;&lt;span&gt;(url).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_download_url&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;video_info);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; file_name &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_file_name&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;video_info).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;filename in video_info is present&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;download_file&lt;&#x2F;span&gt;&lt;span&gt;(url.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;(), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert!&lt;&#x2F;span&gt;&lt;span&gt;(Path::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;exists&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;In order to fulfill that final test we need to somehow create filenames. I suggest to just pick it up from the video info.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_video_file_name&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;video_info&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;Value) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(name) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; video_info[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;videoDetails&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;][&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;title&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;].&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;.mp4&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, name))
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Finally the actual download function implementation: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;download_file&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;url&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;file_name&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;()&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Url::parse(url)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; resp &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Client::new().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(url.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;send&lt;&#x2F;span&gt;&lt;span&gt;()&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; out &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;std::fs::File::create(file_name)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    std::io::copy(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; resp, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut&lt;&#x2F;span&gt;&lt;span&gt; out)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(())
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Here we make a simple get request by the found download link and after that save a contents to a file.
Seems works. Great!&lt;&#x2F;p&gt;
&lt;p&gt;Finally lets finish our main function:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;main&lt;&#x2F;span&gt;&lt;span&gt;() -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;()&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; args: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;env::args().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(link) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; args.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1&lt;&#x2F;span&gt;&lt;span&gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; video_info &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_info&lt;&#x2F;span&gt;&lt;span&gt;(link)&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; url &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_download_url&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;video_info).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;video download url found&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; file_name &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_video_file_name&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;video_info).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;filename in video_info is present&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;download_file&lt;&#x2F;span&gt;&lt;span&gt;(url, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;file_name[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..&lt;&#x2F;span&gt;&lt;span&gt;])&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(())
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Err&lt;&#x2F;span&gt;&lt;span&gt;(anyhow::Error::msg(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;video link must be provided&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        ))
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;And now lets test it how we can use an app from the cli:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; run https:&#x2F;&#x2F;www.youtube.com&#x2F;watch&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;v=Bn40gUUd5m0
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;After that you can see the downloaded file in the project root folder.&lt;&#x2F;p&gt;
&lt;p&gt;Also we can do:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; target&#x2F;debug
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;.&#x2F;youtube-downloader&lt;&#x2F;span&gt;&lt;span&gt; https:&#x2F;&#x2F;www.youtube.com&#x2F;watch&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;v=Bn40gUUd5m0
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;So if you want to be able to use it from any location you need to do:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ln -s &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;path-to--your-executable&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;~&lt;&#x2F;span&gt;&lt;span&gt;&#x2F;bin
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# after that 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;youtube-downloader&lt;&#x2F;span&gt;&lt;span&gt; https:&#x2F;&#x2F;www.youtube.com&#x2F;watch&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;v=Bn40gUUd5m0
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# but be careful since now it downloads the file relative to the location
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# so probably if you want use it in such way you need to implement an additional arg
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# which specifies a path where the file should be stored
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;h2 id=&quot;conclusion&quot;&gt;Conclusion&lt;a class=&quot;zola-anchor&quot; href=&quot;#conclusion&quot; aria-label=&quot;Anchor link for: conclusion&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;As you see the implementation is trivial and could be done in an hour including googling.&lt;&#x2F;p&gt;
&lt;p&gt;You can add more features such as:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;select the quality&lt;&#x2F;li&gt;
&lt;li&gt;select video or only audio&lt;&#x2F;li&gt;
&lt;li&gt;show a progress bar while downloading&lt;&#x2F;li&gt;
&lt;li&gt;batch save when needed to save many videos&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
</description>
      </item>
      <item>
          <title>MYOX: C compiler: 2</title>
          <pubDate>Wed, 09 Sep 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox-c-compiler-2/</link>
          <guid>https://kakoc.blog/blog/myox-c-compiler-2/</guid>
          <description>&lt;p&gt;&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox&#x2F;&quot;&gt;MYOX: what does it mean?&lt;&#x2F;a&gt;&lt;br &#x2F;&gt;
&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox-c-compiler-1&#x2F;&quot;&gt;Previous chapter&lt;&#x2F;a&gt;&lt;&#x2F;p&gt;
&lt;h2 id=&quot;what-we-ve-done-before&quot;&gt;What we&#x27;ve done before&lt;a class=&quot;zola-anchor&quot; href=&quot;#what-we-ve-done-before&quot; aria-label=&quot;Anchor link for: what-we-ve-done-before&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;In the previous chapter we firstly looked at what actually a programming language is(from the high level) and implemented a compiler part which is called Scanner. Scanner scans initial text of the program and splits it into tokens aka lexemes.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;what-will-we-do&quot;&gt;What will we do?&lt;a class=&quot;zola-anchor&quot; href=&quot;#what-will-we-do&quot; aria-label=&quot;Anchor link for: what-will-we-do&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;In this chapter we are going to implement Parser. The idea behind it is to traverse tokens and try to treat a group of them as a something meaningful and if so do appropriate actions.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;parser&quot;&gt;Parser&lt;a class=&quot;zola-anchor&quot; href=&quot;#parser&quot; aria-label=&quot;Anchor link for: parser&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Lets create a new version of our compiler:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# c_compiler root
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; new 02_parser
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# add 02_parser to Cargo.toml as a workspace member
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# copy all code from the previous chapter
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cp -r&lt;&#x2F;span&gt;&lt;span&gt; 01_scanner&#x2F;src&#x2F;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt; 02_parser&#x2F;src&#x2F;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; 02_parser&#x2F;src
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;touch&lt;&#x2F;span&gt;&lt;span&gt; parser.rs
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# add &amp;quot;mod parser&amp;quot; to main.rs
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now lets talk a bit about what we are going to do.&lt;br &#x2F;&gt;
Look, the idea behind the parser is to treat a sequence of tokens as a something meaningful. But how actually we know that that combination makes sense but another doesn&#x27;t? And the answer is - we have a language and our language has rules. Lets specify them:&lt;&#x2F;p&gt;
&lt;pre style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot;&gt;&lt;code&gt;&lt;span&gt;expression: number
&lt;&#x2F;span&gt;&lt;span&gt;            | expression &amp;#39;*&amp;#39; expression
&lt;&#x2F;span&gt;&lt;span&gt;            | expression &amp;#39;&#x2F;&amp;#39; expression
&lt;&#x2F;span&gt;&lt;span&gt;            | expression &amp;#39;+&amp;#39; expression
&lt;&#x2F;span&gt;&lt;span&gt;            | expression &amp;#39;-&amp;#39; expression
&lt;&#x2F;span&gt;&lt;span&gt;            ;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;number:     T_INTLIT
&lt;&#x2F;span&gt;&lt;span&gt;            ;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;After first look it could be strange, but don&#x27;t worry lets walk through it. Firstly that scheme notation has a particular name: &lt;a href=&quot;https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Backus%E2%80%93Naur_form&quot;&gt;BNF&lt;&#x2F;a&gt;. And the idea behind it is to show generically our language grammar via a recursion and substitution.&lt;br &#x2F;&gt;
Suppose we have a program &amp;quot;2 + 2 * 2&amp;quot;. Lets try to figure out whether our language can understand that sequence. After Scanner we have something like:&lt;&#x2F;p&gt;
&lt;p&gt;&amp;quot;[TI(2), TS(+), TI(2), TS(*), TI(2)]&amp;quot;.&lt;br &#x2F;&gt;
With our grammar: firstly we read &amp;quot;2&amp;quot; but it&#x27;s not the last symbol, so we can&#x27;t to stop. If &amp;quot;2&amp;quot; is not a number it can be probably an expression(| stands for or). So we see that the expression could be also a number. So that we can use it for our &amp;quot;2&amp;quot;. But we don&#x27;t have a single expression rule inside root expression(it&#x27;s always used with &amp;quot;| (+ | - | * | &#x2F; |) expression&amp;quot;). So we need to read the next symbol. The next symbol is &amp;quot;+&amp;quot;. And we have so rule(expression &#x27;+&#x27; expression). We see that there are no other rules which can be used so we need to try to expand that one. We&#x27;ve read &amp;quot;2&amp;quot;, &amp;quot;+&amp;quot;, after that we read 2. To can be number or expression, but we haven&#x27;t finished so lets try find something other. Behind &amp;quot;2&amp;quot; there is &amp;quot;&lt;em&gt;&amp;quot; and we see that there is &amp;quot;expression &#x27;&lt;&#x2F;em&gt;&#x27; expression&amp;quot; rule. Lets try to expand it. We&#x27;ve read &amp;quot;2 + 2 &lt;em&gt;&amp;quot; no we see &amp;quot;2&amp;quot;. It&#x27;s the last symbol and we have a rule that it could be the number, and number can be the expression. So that it fits to our last &amp;quot;expression &#x27;&lt;&#x2F;em&gt;&#x27; expression&amp;quot; rule.&lt;&#x2F;p&gt;
&lt;p&gt;I hope that that explanation can clarify the basic idea. In future chapters via such notation we will expand our language with new constructs and also solve other tasks(such as precedence of &amp;quot;*&amp;quot; over &amp;quot;+&amp;quot;).&lt;&#x2F;p&gt;
&lt;p&gt;Now, after the explanation of the core idea I want to begin with tests we can show more info about what do we want to achieve.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; parser.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_parser_eval&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;2 + 3 * 5 - 8 &#x2F; 3&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; expected &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;11&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; res &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;interpret_ast&lt;&#x2F;span&gt;&lt;span&gt;(Parser::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i)).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;parse&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(expected, res);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;13 -6+  4*
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;5
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;       +
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;08 &#x2F; 3&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; expected &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= -&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;21&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; res &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;interpret_ast&lt;&#x2F;span&gt;&lt;span&gt;(Parser::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i)).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;parse&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(expected, res);
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;should_panic&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_parser_invalid_program&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;12 34 + -56 * &#x2F; - - 8 + * 2&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; res &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;interpret_ast&lt;&#x2F;span&gt;&lt;span&gt;(Parser::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i)).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;parse&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;An attentive reader may notice that currently our evaluation doesn&#x27;t take care about the precedence. As I said earlier we will do it in the next chapters.&lt;&#x2F;p&gt;
&lt;p&gt;Now lets talk about what actual output from Parser is. The output from Parser is a famous Abstract Syntax Tree term. When we hear &amp;quot;tree&amp;quot; we always can think as a recursive nature about it. And now it will be very useful. As I demonstrated earlier when parsing the sequence of tokens we work with a recursive nature. Lets slowly begin: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use super&lt;&#x2F;span&gt;&lt;span&gt;::scan::{Scanner, Token &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;as&lt;&#x2F;span&gt;&lt;span&gt; ScannerToken};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::iter::Peekable;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; every meaningful token from Scaner has a corresponding tree node
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;AstNode &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;token&lt;&#x2F;span&gt;&lt;span&gt;: Token,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;left&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;AstNode&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;right&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;AstNode&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; just keeping pointer on spanning elements advance through them
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Parser &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;scanned&lt;&#x2F;span&gt;&lt;span&gt;: Peekable&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;std::vec::IntoIter&amp;lt;ScannerToken&amp;gt;&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Parser &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;new&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ScannerToken&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;		Parser {
&lt;&#x2F;span&gt;&lt;span&gt;            scanned: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;::new(tokens.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_iter&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;peekable&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now we are going to begin to implement &lt;a href=&quot;https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Recursive_descent_parser&quot;&gt;Recursive Decent Technique&lt;&#x2F;a&gt;. The basic idea is that we somehow try to go from top to down over the rules(from most complex to the most simple) and from the bottom begin to build our actual ast nodes.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;enum &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Token &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;    AAdd,
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;    ASubtract,
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;    AMultiply,
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;    ADivide,
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;    AIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;i64&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; new methouds inside Parser
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; as i said we begin with most complex to the most simple
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;parse&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;bin_expr&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;bin_expr&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; left &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;primary&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.scanned.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;peek&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;		&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return&lt;&#x2F;span&gt;&lt;span&gt; left;
&lt;&#x2F;span&gt;&lt;span&gt;	}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; middle &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;arithop&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.scanned.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; right &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;bin_expr&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;	AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;		token: middle,
&lt;&#x2F;span&gt;&lt;span&gt;		left: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;::new(left)),
&lt;&#x2F;span&gt;&lt;span&gt;		right: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;::new(right)),
&lt;&#x2F;span&gt;&lt;span&gt;	}
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;primary&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.scanned.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;		&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(ScannerToken::TIntlit(v)) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;make_ast_leaf&lt;&#x2F;span&gt;&lt;span&gt;(Token::AIntlit(v)),
&lt;&#x2F;span&gt;&lt;span&gt;		&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;panic!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;invalid token&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;	}
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; helpers to make life easier
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;make_ast_leaf&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;token&lt;&#x2F;span&gt;&lt;span&gt;: Token) -&amp;gt; AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;    AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;        token,
&lt;&#x2F;span&gt;&lt;span&gt;        left: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;        right: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;make_ast_unary&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;token&lt;&#x2F;span&gt;&lt;span&gt;: Token, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;left&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;AstNode&amp;gt;) -&amp;gt; AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;    AstNode {
&lt;&#x2F;span&gt;&lt;span&gt;        token,
&lt;&#x2F;span&gt;&lt;span&gt;        left: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(left),
&lt;&#x2F;span&gt;&lt;span&gt;        right: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;arithop&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;token&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;ScannerToken) -&amp;gt; Token {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use super&lt;&#x2F;span&gt;&lt;span&gt;::scan::Token &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;as&lt;&#x2F;span&gt;&lt;span&gt; ScannerToken;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match *&lt;&#x2F;span&gt;&lt;span&gt;token {
&lt;&#x2F;span&gt;&lt;span&gt;        ScannerToken::TPlus &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;Token::AAdd,
&lt;&#x2F;span&gt;&lt;span&gt;        ScannerToken::TMinus &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;Token::ASubtract,
&lt;&#x2F;span&gt;&lt;span&gt;        ScannerToken::TStar &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;Token::AMultiply,
&lt;&#x2F;span&gt;&lt;span&gt;        ScannerToken::TSlash &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;Token::ADivide,
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;panic!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;unknown token in arithop()&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;), &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; fprintf(stderr, &amp;quot;unknown token in arithop() on line %d\n&amp;quot;, Line);
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;ScannerToken&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; scanner &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Scanner::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;i);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; ts &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;while &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(t) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; scanner.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;scan&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        ts.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(t);
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    ts
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Finally we need a way how we can actually intrepret the ast.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;interpret_ast&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;root&lt;&#x2F;span&gt;&lt;span&gt;: AstNode) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;i64 &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span&gt;Token::AIntlit(v) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; root.token {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return&lt;&#x2F;span&gt;&lt;span&gt; v;
&lt;&#x2F;span&gt;&lt;span&gt;    } &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;else &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; left &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;interpret_ast&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;root.left.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; right &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;interpret_ast&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;root.right.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; root.token {
&lt;&#x2F;span&gt;&lt;span&gt;            Token::AAdd &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt; left &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt; right,
&lt;&#x2F;span&gt;&lt;span&gt;            Token::ASubtract &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt; left &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-&lt;&#x2F;span&gt;&lt;span&gt; right,
&lt;&#x2F;span&gt;&lt;span&gt;            Token::AMultiply &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt; left &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt; right,
&lt;&#x2F;span&gt;&lt;span&gt;            Token::ADivide &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt; left &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt; right,
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;panic!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;invalid operations tree&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;h2 id=&quot;conclusion&quot;&gt;Conclusion&lt;a class=&quot;zola-anchor&quot; href=&quot;#conclusion&quot; aria-label=&quot;Anchor link for: conclusion&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;In this chapter we explored what actually parsing process is, how can do it as well as how we can describe our language in a more formal, strict way.&lt;br &#x2F;&gt;
I&#x27;m sure that there are a lot of questions about recursive decent parsing. And based on my experience you won&#x27;t understand it without playing with it. So I suggest to as an exercise implement a pretty printer - the tool which traverses tokens from scanner and print the ast in the appropriate way. &lt;&#x2F;p&gt;
&lt;h2 id=&quot;next-steps&quot;&gt;Next steps&lt;a class=&quot;zola-anchor&quot; href=&quot;#next-steps&quot; aria-label=&quot;Anchor link for: next-steps&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;In the next chapters we will fix the precedence problem and finally begin to generate an assembly code.&lt;&#x2F;p&gt;
</description>
      </item>
      <item>
          <title>MYOX: C compiler: 1</title>
          <pubDate>Tue, 08 Sep 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox-c-compiler-1/</link>
          <guid>https://kakoc.blog/blog/myox-c-compiler-1/</guid>
          <description>&lt;p&gt;&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox&#x2F;&quot;&gt;MYOX: what does it mean?&lt;&#x2F;a&gt;&lt;br &#x2F;&gt;
&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox-c-compiler-0&#x2F;&quot;&gt;Previous chapter&lt;&#x2F;a&gt;&lt;&#x2F;p&gt;
&lt;h2 id=&quot;what-will-we-do&quot;&gt;What will we do?&lt;a class=&quot;zola-anchor&quot; href=&quot;#what-will-we-do&quot; aria-label=&quot;Anchor link for: what-will-we-do&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;All big things are built from smaller and more simple.
In the next few chapters we basically will build a texted calculator. It means that we will be able to write a program which consists of mathematical operations and could be compiled into assembly languge which after that can be executed.
But as we will see later the new functionality to our &amp;quot;calculator&amp;quot; will be appended in a trivial way(at least most of it) since with &amp;quot;calculator&amp;quot; we will build a foundation of our compiler.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;natural-languages-programming-languages&quot;&gt;Natural languages, programming languages&lt;a class=&quot;zola-anchor&quot; href=&quot;#natural-languages-programming-languages&quot; aria-label=&quot;Anchor link for: natural-languages-programming-languages&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;blockquote&gt;
&lt;p&gt;&amp;quot;int foo = 10;&amp;quot;&lt;br &#x2F;&gt;
&amp;quot;My name is Konstantin.&amp;quot;&lt;&#x2F;p&gt;
&lt;&#x2F;blockquote&gt;
&lt;p&gt;What do these languages have in common? A lot of.&lt;&#x2F;p&gt;
&lt;p&gt;Every languge consists of symbols.&lt;br &#x2F;&gt;
Every symbol has a meaning.&lt;br &#x2F;&gt;
Some symbols can be combined together so that we achieve the new meaning. We can say that a group of symbols with the meaning is a word.&lt;br &#x2F;&gt;
Words also can be combined together, and a group of words can have the new meaning. We can say that the group of words is a sentence(in our natural language), or statement, expression(in programing languages. Don&#x27;t bother we will talk about that in the future in a more detail).&lt;br &#x2F;&gt;
Sentences can be combined into parapraphs. Statements can be combined into functions.&lt;br &#x2F;&gt;
Parapraphs can be combined into chapters. Functions could be combined into modules.&lt;br &#x2F;&gt;
Chapters form a text. Modules form a program.&lt;&#x2F;p&gt;
&lt;p&gt;I hope that now you see that actually there are a lot of common. The boundaries of differences blur.&lt;br &#x2F;&gt;
I suggest to reflect on this.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;scanner&quot;&gt;Scanner&lt;a class=&quot;zola-anchor&quot; href=&quot;#scanner&quot; aria-label=&quot;Anchor link for: scanner&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Now lets start to do first steps with our compiler:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# c_compiler(project root)
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; new 01_scanner
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# open Cargo.toml and append &amp;quot;01_scanner&amp;quot; as a workspace member
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; 01_scanner
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;As I said previously our language consists of symbols. Symbols can be combined together into words. So that lets treat our program(text file) as a sequence of symbols. We will read all symbols from left to right while trying to group them into words when it makes sense or left as a separate self sufficient thing or fail when there is a sequence which is not possible in our language. The abstraction which is responsible for doing such stuff we will call &lt;strong&gt;Scanner&lt;&#x2F;strong&gt;.&lt;&#x2F;p&gt;
&lt;p&gt;Lets create a new file &lt;em&gt;scan.rs&lt;&#x2F;em&gt; in &lt;em&gt;src&#x2F;&lt;&#x2F;em&gt;:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;touch&lt;&#x2F;span&gt;&lt;span&gt; src&#x2F;scan.rs
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# append &amp;quot;mod scan;&amp;quot; to src&#x2F;main.rs
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now lets introduce a type which will describe every known symbol in our current version the language.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;derive&lt;&#x2F;span&gt;&lt;span&gt;(PartialEq, Debug)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;enum &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Token &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;    TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;    TStar,
&lt;&#x2F;span&gt;&lt;span&gt;    TSlash,
&lt;&#x2F;span&gt;&lt;span&gt;    TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;I hope that you see the basic idea behind &lt;strong&gt;Token&lt;&#x2F;strong&gt; and &lt;strong&gt;Scanner&lt;&#x2F;strong&gt;. In order to clarify it more lets begin with tests. They should demonstrate more precisely what we want to achieve and also it&#x27;s a good practice which should be followed when it&#x27;s possible.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; scan.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cfg&lt;&#x2F;span&gt;&lt;span&gt;(test)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use super&lt;&#x2F;span&gt;&lt;span&gt;::Token::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use super&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Token&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; scanner &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Scanner::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;i);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; ts &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;while &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(t) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; scanner.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;scan&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;            ts.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(t);
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        ts
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;compare_expected_with_scanned&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;expected&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Token&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;scanned&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Token&amp;gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(expected.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;(), scanned.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        expected.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;zip&lt;&#x2F;span&gt;&lt;span&gt;(scanned.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;for_each&lt;&#x2F;span&gt;&lt;span&gt;(|(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;l&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;r&lt;&#x2F;span&gt;&lt;span&gt;)| {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;assert_eq!&lt;&#x2F;span&gt;&lt;span&gt;(l, r);
&lt;&#x2F;span&gt;&lt;span&gt;        });
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_scan1&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;2 + 3 * 5 - 8 &#x2F; 3&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;compare_expected_with_scanned&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;3&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TStar,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;5&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;8&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TSlash,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;3&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;            ],
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i),
&lt;&#x2F;span&gt;&lt;span&gt;        );
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_scan2&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;13 -6+  4*
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;5
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;       +
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;08 &#x2F; 3&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;compare_expected_with_scanned&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;13&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;6&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;4&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TStar,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;5&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;8&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TSlash,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;3&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;            ],
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i),
&lt;&#x2F;span&gt;&lt;span&gt;        );
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_scan3&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;12 34 + -56 * &#x2F; - - 8 + * 2&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;compare_expected_with_scanned&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;12&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;34&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;                TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;56&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TStar,
&lt;&#x2F;span&gt;&lt;span&gt;                TSlash,
&lt;&#x2F;span&gt;&lt;span&gt;                TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;                TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;8&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;                TStar,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;            ],
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i),
&lt;&#x2F;span&gt;&lt;span&gt;        );
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_scan4&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;23 +
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;18 -
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;45.6 * 2
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&#x2F; 18&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;compare_expected_with_scanned&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;23&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TPlus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;18&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TMinus,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;45&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TStar,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;2&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;                TSlash,
&lt;&#x2F;span&gt;&lt;span&gt;                TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;18&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;            ],
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i),
&lt;&#x2F;span&gt;&lt;span&gt;        );
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;test&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    #[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;should_panic&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;test_scan5&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; i &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;23 * 456abcdefg&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;compare_expected_with_scanned&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;23&lt;&#x2F;span&gt;&lt;span&gt;), TStar, TIntlit(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;456&lt;&#x2F;span&gt;&lt;span&gt;)], &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_tokens_list&lt;&#x2F;span&gt;&lt;span&gt;(i));
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now when we have a shape of our Scanner lets implement it.&lt;br &#x2F;&gt;
Algorthmic idea behind Scanner: lets read character one by one. When we know that it&#x27;s self sufficient character(e.g. &amp;quot;+&amp;quot;) lets create an appropriate token. When we think that the current character is a part of some more big thing lets move forward until the whole big thing isn&#x27;t built(e.g. we read &amp;quot;1&amp;quot; of number &amp;quot;123&amp;quot;. Now we need to read &amp;quot;2&amp;quot; after that &amp;quot;3&amp;quot; and after that say that we have a number literal token = 123). Also we should take care about useless characters such as empty lines, spaces. Sometimes we can receive the wrong sequence of symbols, the sequence which we can&#x27;t recognize(e.g. &amp;quot;456abcdefg&amp;quot;) in such cases we just abort compilation(we will add an error handling in the future).&lt;br &#x2F;&gt;
I think that based on the above discription and tests you can implement Scanner on your own and I encourage you to do that.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; scan.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::{iter::Peekable, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;::Chars};
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; our scanner basically refers to a read text file, its contents via stream of chars
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; while advancing in reading scanner fills tokens vector, 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; basic blocks with the meaning of our program
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; for advancing we will use built in rust Peekable stream.
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; it offers us out of the box the ability to advance over characters, 
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; see the next without advancing
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Scanner&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;stream&lt;&#x2F;span&gt;&lt;span&gt;: Peekable&amp;lt;Chars&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Token&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Scanner&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; since we just read, but not modify and  
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; the read text basically should leave at least equal to scanner&amp;#39;s lifetime 
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we void unnecessary copying 
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;new&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;S: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;AsRef&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;stream&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;a&lt;&#x2F;span&gt;&lt;span&gt; S) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            stream: stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_ref&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;chars&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;peekable&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;            tokens: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[],
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; as it was said lets skip whitespaces and
&lt;&#x2F;span&gt;&lt;span&gt;	&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; pay attention only on the useful stuff
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;char&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;skip_whitespace&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;skip_whitespace&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;while &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39; &amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\t&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\n&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\r&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;peek&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;scan&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;Token&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; ch &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;if &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;==&lt;&#x2F;span&gt;&lt;span&gt; ch {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;return &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; ch.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;+&amp;#39; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(Token::TPlus),
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;-&amp;#39; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(Token::TMinus),
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;*&amp;#39; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(Token::TStar),
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;&#x2F;&amp;#39; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(Token::TSlash),
&lt;&#x2F;span&gt;&lt;span&gt;            ch1 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;@ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;0&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;9&amp;#39; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; num &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, ch1.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_owned&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;while &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(ch2 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;@ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;1&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;9&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;peek&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                    num &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, num, ch2);
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;                }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; skip all after dot when float
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;while &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;1&amp;#39;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;..=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;9&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;#39;.&amp;#39;&lt;&#x2F;span&gt;&lt;span&gt;) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;peek&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.stream.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;next&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;                }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(Token::TIntlit(num.parse::&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()))
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_ =&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;panic!&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;h2 id=&quot;conclusion&quot;&gt;Conclusion&lt;a class=&quot;zola-anchor&quot; href=&quot;#conclusion&quot; aria-label=&quot;Anchor link for: conclusion&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;In this chapter we discussed how we can treat our program, its structure, compared with natural language and saw that there are a lot of similarities.&lt;br &#x2F;&gt;
Next we implemented Scanner, the thing which receives a text of the program(sequence of symbols) and splits it into Tokens.&lt;&#x2F;p&gt;
&lt;p&gt;In the next chapter we will meet with Parser. The thing which tries to understand the meaning of Tokens(= words) sequence and based on that do appropriate actions.&lt;&#x2F;p&gt;
</description>
      </item>
      <item>
          <title>MYOX: C compiler: 0</title>
          <pubDate>Mon, 07 Sep 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox-c-compiler-0/</link>
          <guid>https://kakoc.blog/blog/myox-c-compiler-0/</guid>
          <description>&lt;p&gt;&lt;a href=&quot;https:&#x2F;&#x2F;kakoc.blog&#x2F;blog&#x2F;myox&#x2F;&quot;&gt;MYOX: what does it mean?&lt;&#x2F;a&gt;&lt;&#x2F;p&gt;
&lt;h2 id=&quot;foreword&quot;&gt;Foreword&lt;a class=&quot;zola-anchor&quot; href=&quot;#foreword&quot; aria-label=&quot;Anchor link for: foreword&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Have you ever thought how the tool which you use every day actually works? At least on the basic level? In this series I want to demonstrate how to build C compiler from scratch. Actually there are a lot of stuff in the Internet about how to build interpreters. But the amount of work needed to build the interpreter vs compiler is extremely different. Compilers are much harder to implement, develop and maintain. This is why nowadays we mostly use interpreted languages. But it doesn&#x27;t mean that compilers aren&#x27;t more needed. It&#x27;s a development, it&#x27;s all about tradeoffs. Compilers can offer things which interpreters can not and vise versa. For the compilers introduction I redirect you to &lt;a href=&quot;https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Compiler&quot;&gt;wiki&lt;&#x2F;a&gt;.&lt;br &#x2F;&gt;
From the learning point of view I think that after understanding how to write the compiler you can easily understand how to write an intepreter almost without any additional knowledge. But if reverse that statement it won&#x27;t be true. A lot of pieces will be missed. This is why we will write the compiler.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;how&quot;&gt;How&lt;a class=&quot;zola-anchor&quot; href=&quot;#how&quot; aria-label=&quot;Anchor link for: how&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;This series will be splitted into articles. Every article is a self sufficient chunk. The next article will modify the previous one + append something new.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;base&quot;&gt;Base&lt;a class=&quot;zola-anchor&quot; href=&quot;#base&quot; aria-label=&quot;Anchor link for: base&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Now lets create a project with a base structure. As I said earlier we will develope incrementally. Every new chapter it&#x27;s a new verison of our compiler. We can do that with our version control system. But I prefer to have previous versions explicitely because it&#x27;s easier to analyze with previous&#x2F;next versions, make changes. From the Rust perspective I&#x27;m going to use &lt;a href=&quot;https:&#x2F;&#x2F;doc.rust-lang.org&#x2F;book&#x2F;ch14-03-cargo-workspaces.html&quot;&gt;workspaces&lt;&#x2F;a&gt; for that.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; new c_compiler
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;cd&lt;&#x2F;span&gt;&lt;span&gt; c_compiler
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;rm -r&lt;&#x2F;span&gt;&lt;span&gt; src
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Since we are going to use workspaces lets go to the &lt;code&gt;Cargo.toml&lt;&#x2F;code&gt;, remove all its contets and append:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;toml&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-toml &quot;&gt;&lt;code class=&quot;language-toml&quot; data-lang=&quot;toml&quot;&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;workspace&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;members &lt;&#x2F;span&gt;&lt;span&gt;= [
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;lt;here we will place a name of the workspace&amp;gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Next versions of our compilers will be created via: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; new &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;name&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
</description>
      </item>
      <item>
          <title>Sports activities for a programmer</title>
          <pubDate>Tue, 01 Sep 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/sports-activities/</link>
          <guid>https://kakoc.blog/blog/sports-activities/</guid>
          <description>&lt;h2 id=&quot;intro&quot;&gt;Intro&lt;a class=&quot;zola-anchor&quot; href=&quot;#intro&quot; aria-label=&quot;Anchor link for: intro&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;I&#x27;ve tried a lot of different sports activities and want to share my experience with them.&lt;br &#x2F;&gt;
Also my goal is to highlight those which are more appropriate for the programmer.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;reflection&quot;&gt;Reflection&lt;a class=&quot;zola-anchor&quot; href=&quot;#reflection&quot; aria-label=&quot;Anchor link for: reflection&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;There are different kinds of sports and they have different requirements from you: &lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;concentration&lt;&#x2F;li&gt;
&lt;li&gt;explosion &lt;&#x2F;li&gt;
&lt;li&gt;release a lot of energy for a short period of time&lt;&#x2F;li&gt;
&lt;li&gt;monotonous work with low energy consumption&lt;&#x2F;li&gt;
&lt;li&gt;equipment&lt;&#x2F;li&gt;
&lt;li&gt;commute&lt;&#x2F;li&gt;
&lt;li&gt;recovery&lt;&#x2F;li&gt;
&lt;li&gt;variety&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;All these bullets influence the choice.&lt;&#x2F;p&gt;
&lt;p&gt;Based on my experience when you have a lot of brainwork it&#x27;s hard to do explosion work, work when you need to release a lot of energy for a short period of time, work when you need to keep the high concentration level.&lt;br &#x2F;&gt;
The basic idea is that all those factors don&#x27;t allow you to relax. Instead they unwind the psyche and as the result I come from such trainings more tired + I need more time for recovery.&lt;br &#x2F;&gt;
Examples:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;gym&lt;&#x2F;li&gt;
&lt;li&gt;martial arts(boxing gym, wrestling, mma)&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;Instead of being &amp;quot;aggresive&amp;quot; lets consider other:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;swimming&lt;&#x2F;li&gt;
&lt;li&gt;running&lt;&#x2F;li&gt;
&lt;li&gt;cycling&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;At such work you can do useful job and at the same time think about life, admire the surroundings(not with swimming =)). Also it&#x27;s a good opportunity for travelling. There are a lot of marathons, cycling competitins over the world. Additionally I found that it improves your psyche, because for the first time it&#x27;s really hard to run 20km for example. And not because of high physical load, but because it&#x27;s a long period of time. You need some time to learn how to look forward and abstract from the outside world, otherwise you can &amp;quot;eat&amp;quot; yourself from the inside by your thoughts. So yes this is some sort of meditation skill which you will develop with time.&lt;br &#x2F;&gt;
A small tip: try to train without music because it doesn&#x27;t allow you to relax, most of the time you listen music and its give you a mental power for work on the training, so you don&#x27;t control the training, you do training just because of music. You should find a way of control such things on your own, just with your mind, without any factors from the outside.&lt;&#x2F;p&gt;
&lt;p&gt;So I run a couple of times in the week and started to look for the same activities. I found swimming, cycling and even the dedicated kind of sport - triathlon. I begun to swim, spin cycle and it gave me even more satisfaction. Because after that my sports activities are very varied. With such schedule really hard to be busy mentally.&lt;br &#x2F;&gt;
Drawbacks: &lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;for cycling need a cycle + bike station -&amp;gt; $$$&lt;&#x2F;li&gt;
&lt;li&gt;for swimming need to go to a dedicated place and spend much time before and after a swimming pool&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;h2 id=&quot;conclusion&quot;&gt;Conclusion&lt;a class=&quot;zola-anchor&quot; href=&quot;#conclusion&quot; aria-label=&quot;Anchor link for: conclusion&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;For programmers from my point of view suitable sports activities are:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;swimming&lt;&#x2F;li&gt;
&lt;li&gt;running&lt;&#x2F;li&gt;
&lt;li&gt;cycling&lt;&#x2F;li&gt;
&lt;li&gt;football&lt;&#x2F;li&gt;
&lt;li&gt;volleyball&lt;&#x2F;li&gt;
&lt;li&gt;basketball&lt;&#x2F;li&gt;
&lt;li&gt;tennis&lt;&#x2F;li&gt;
&lt;li&gt;yoga&lt;&#x2F;li&gt;
&lt;li&gt;gym(only light)&lt;&#x2F;li&gt;
&lt;li&gt;rock climbing&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;But not: &lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;powerlifting, &lt;&#x2F;li&gt;
&lt;li&gt;weightlifting&lt;&#x2F;li&gt;
&lt;li&gt;martial arts&lt;&#x2F;li&gt;
&lt;li&gt;boxing&lt;&#x2F;li&gt;
&lt;li&gt;wrestling&lt;&#x2F;li&gt;
&lt;li&gt;mma&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
</description>
      </item>
      <item>
          <title>Personalized workspace</title>
          <pubDate>Tue, 25 Aug 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/personalization/</link>
          <guid>https://kakoc.blog/blog/personalization/</guid>
          <description>&lt;h2 id=&quot;foreword&quot;&gt;Foreword&lt;a class=&quot;zola-anchor&quot; href=&quot;#foreword&quot; aria-label=&quot;Anchor link for: foreword&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Operating systems, text editors, keyboards, keyboard keymaps, workplaces - I&#x27;ve tried to work with different types of them and want to share my thoughts and conclusions about such &amp;quot;personalizations&amp;quot;.&lt;br &#x2F;&gt;
Initially I wanted to describe the every aspect individually. But after a couple of sentences I had figured out that those things are mostly related to each other, intersect with each other. So this is why I&#x27;m planning to just describe the whole story, without any separations.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;journey&quot;&gt;Journey&lt;a class=&quot;zola-anchor&quot; href=&quot;#journey&quot; aria-label=&quot;Anchor link for: journey&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;&lt;strong&gt;Windows&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;As probably most of us I started with Windows. At that time it was really annoying to fullstack develop web applications with Windows(docker, console, tools). All looked like hacks with hacks. So I switched to OS X. For the sanity purpose as I&#x27;m hearing now from my colleagues - Windows is a good OS for developers too.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;Dvorak Programmer&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;Being a Windows user and while learning programming, maybe when I was procrastinating, but I begun to thought about boundaries. And the first boundary which came up to my mind was under my fingers - keyboard layout. Why is such keyboard layout used? And I fastly googled that it&#x27;s really mostly due to historical reasons, but not due to ergonomic, performance reasons. After that I fastly googled that there are alternatives such as Dvorak, Dvorak Programmer, Colemak. My choise was Dvorak Programmer(I don&#x27;t remember why particularly a such layout, maybe due to &amp;quot;Programmer&amp;quot; word presense, maybe due to &amp;quot;easy&amp;quot; installation). I instantly installed it and begin to explore. From the first point of view all things made sense. Instead of numbers different programming symbols({},[],(),&amp;amp;,!,$,#), in order to type (&#x27;;,) also no need to press Shift.&lt;br &#x2F;&gt;
~How learnt~: participated in keyboard racing, while strolling tried in mind type different sentences. Basically it wasn&#x27;t so hard transition compared to... Vim.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;OS X&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;This operating system was a very neat for the web development out of the box. Everything was ok...&lt;br &#x2F;&gt;
At that time while watching some tutorial I had found that a guy very quickly did different kinds of movements, text manipulations. I started to looking for what kind of editor he used. And in the description he pointed out that it was Vim. I fastly googled about Vim and found nice video tutorials about it. But unfortunatelly it was so hard to begin with. A lot of configs, plugins, tools, which were needed for comfortable work. I had a couple of attempts to start programming with terminal vim and all those attempts I failed. I really liked the idea behind text editing, navigation, but I didn&#x27;t like to do a lot of configurations. I discovered that all popular editors(such as intellij, atom, vscode) can support that vim style editing which I particularly wanted. So at that time it was a perfect solution for me. I installed Vim plugin into my WebStorm IDE and begun to live with Dvorak Programmer, Vim and WebStorm. Over time in one day at work(it was my first working day) I&#x27;ve faced with the problem that my Web Storm license was for students but I was beginning to develop corporate software and this I needed to buy Web Storm or switch to the other IDE&#x2F;editor. I decided to switch to VSCode. But with VSCode I faced with the problem that with Vim plugin text editing&#x2F;movements are really weird - high latency, from time to time unexpected movements. Vim plugin could be ok when your project is small, but editing in big files is really weird. And I&#x27;m not talking about files with 10k lines, 150 lines are enough to get a weird editing feedback. And that was basically the time when I tried Emacs at my work. But don&#x27;t think that it was a quick and easy transition. Range between switching from WebStorm to VSCode and between switching from VSCode to Emacs is equal around 1 year. When I switched to VSCode at that time I begun to play with Clojure. Emacs the most popular environment for lisp development and Clojure is not an exception. So I started to learn Emacs in my free time.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;Emacs&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;When I firstly installed Emacs it was even ugly than with Vim. Because even without those plugins and other configurations you can do a lot of with it out of the box. But with Emacs it&#x27;s not possible, at least for me. Because out of the box you have so ugly layout for editing&#x2F;movements... I thought that those keymaps were established via a random function. And also new googling and also a new solution. It was SpaceEmacs. The basic idea behind it is that you achieve Vimmed Emacs - you have Emacs with Vim style editing + Emacs&#x27; features. The downside of Spacemacs is that you receive totally reworked Emacs, so that you need to read a lot of materials about Emacs and additionally about Spacemacs. And I&#x27;m not surprised that I&#x27;ve got a lot of problems when I needed to change settings. All that stuff was some sort of a magic. Those layers akin to plugins in Vim in the sense of 0 configuration. But not only magic, desire to control things forced me to switch to classical Emacs and begin to customize it for myself. Spacemacs didn&#x27;t a mistake, it showed me what things with Emacs I can do and perspectives were amazing! Customizing Emacs wasn&#x27;t extremely painful, rather just a long way. Fortunatelly after playing wiht Spacemacs I had a picture in my mind of features which I needed. And fortunatelly for all those features there were screencasts. That way was basically incremental: I edited stuff, found some painfull peaces and after that tried to find a solution(packages, snippets, etc). So yes, it took around 1 year in order to be ready to use Emacs on day to day basis. And now years later I can say that there ara 2 thigs I hate in Emacs: EmacsLisp and the absense of real async.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;To Linux&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;At that time I worked with Emacs + OS X. And at that time I heavily used docker locally + in Emacs&#x27; there were a lot of LSP servers since multiple projects modified at the same time. Those things and I even not talking about opened tabs in browsers ate all available memore of my iMac(16 gb) and I always needed to wait + at that time the was an interesting bug with Angular because of which recompilation time was extremely longer than on Windows, Linux + it was really annoying to I couldn&#x27;t work without mouse in order to be able to work with windows effectively. I tried windows managers on OS X and those are really fake compared to managers which Linux has. &lt;&#x2F;p&gt;
&lt;p&gt;Also after some time I had found that it was extremely uncomfortable to me to place my hand on the mouse every time I needed it. Probably it was a defensive mechanism of my body due to sharp corners of the Apple mouse. Since I&#x27;m touching Apple mouse here sorry but I can&#x27;t ommit the other aspect of Apple mouse: ~charging~: in order to charge Apple keyboard you just need to insert the lightning cable into the socket which is placed on the keyboard front end. So that the keyboard can be charged while you don&#x27;t need to stop your work. Unfortunatelly It&#x27;s not related to Apple mouse. In order to charge Apple mouse you need to flip the mouse on 180degrees so that the backend of the mouse is looking on the ceiling. Because the socket is placed on the mouse&#x27; backend! The charm to such situation adds the notification system which notifies you when around 2% of a battery is left.&lt;br &#x2F;&gt;
It was really a funny situation: when I struggled with such problems Youtube proposed me to watch a video about the genius of Jony Ive =).&lt;&#x2F;p&gt;
&lt;p&gt;Those facts triggered me to switch to Linux.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;Linux&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;Basically the transition to Linux wasn&#x27;t so hard. I had some experience with different Linux distributives. Not all of them were supported at my job so I picked up Mini Ubuntu(Ubuntu without GUI) + i3 instead of Arch. The hardest thing was to configure keymaps since I used Dvorak Programmer. But I needed to do that only once. Now I have bash scripts and it&#x27;s not a problem.&lt;br &#x2F;&gt;
And with setup I begun to feel happy. All needed actions can be performed from the keyboard in simple ways. The only thing which disturbed me was a necessity for some trivial actions in browser to use mouse. But at that time I was a Vim&#x27;er so that I installed Vimium plugin for my browser and all problems are gone.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;Splitted keyboard&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;After some time I started to suffer from pressing keys on my keyboard. It was a simple keyboard from Microsoft which I got with the workstation at my work. I had heard a lot about mechanical keyboard and that are awesome. But I even heard about splitted keyboards and that they give you a right ergonomic. I decided to give it a try and bought ErgoDox EZ. And it was the hardest thing to adopt with: I needed the rebind ~50% of keys + learn how use it in the reality. Again keyboard racing... Too much of them. Rebindings + racings = a lot of time and energy. Finally I started to use it on my day to day basis... And you know what? I didn&#x27;t find any differences, except keys pressing were neat. Probably the reason why it&#x27;s comportable for me to use original keyboard is that I&#x27;m using Dvorak Programmer and with its keymap most of the time your hands are placed in a right, comfortable position. Additionally I needed to work from other country. I switched my workstation to laptop as well as ErgoDox EZ to laptop&#x27;s keyboard and it still suits me.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;Work standing&lt;&#x2F;strong&gt;&lt;&#x2F;p&gt;
&lt;p&gt;While temporary working from abroad in the accomodation but not from the my main home&#x2F;office I didn&#x27;t have a comformtable table, chair. But there was a wide and high windowsill. And I tried to work standing with it. And you know it was an interesting experience. With work standing your mind is always focused, it&#x27;s harder to begin to procrastinate, maybe because your muscles are always toned compared to the relaxed position when you are sitting in the comfortable chair. So that new innovation I brought from Ukrain to my home office and started to work standing on day to day basis. Little nitpicks: need to have a soft rug under you legs + need some time for muscles for adoption: first time it was impossible to work all working day with work standing.&lt;&#x2F;p&gt;
&lt;h2 id=&quot;conclusion&quot;&gt;Conclusion&lt;a class=&quot;zola-anchor&quot; href=&quot;#conclusion&quot; aria-label=&quot;Anchor link for: conclusion&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Based on my way I want to give a feedback about things which are worth themselves and about things which aren&#x27;t. A little notice: it can be not so objectively since when you have some knowledge it can be hard to objectively say whether those knowledge are useful or not just because they have already changed you.&lt;&#x2F;p&gt;
&lt;p&gt;So:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;Windows - yes(nowadays)&lt;&#x2F;li&gt;
&lt;li&gt;Linux - yes&lt;&#x2F;li&gt;
&lt;li&gt;OS X - no. Every year worse and worse&lt;&#x2F;li&gt;
&lt;li&gt;Dvorak Programmer - no(time for adoption, always a lot of configurations, impossible to work on other people&#x27;s computers)&lt;&#x2F;li&gt;
&lt;li&gt;Vim - yes&lt;&#x2F;li&gt;
&lt;li&gt;Emacs - yes&lt;&#x2F;li&gt;
&lt;li&gt;Splitted Keyboard - no&lt;&#x2F;li&gt;
&lt;li&gt;Work standing - yes&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
</description>
      </item>
      <item>
          <title>MYOX: full text search engine</title>
          <pubDate>Sat, 15 Aug 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox-ftse/</link>
          <guid>https://kakoc.blog/blog/myox-ftse/</guid>
          <description>&lt;h1 id=&quot;full-text-search-engine&quot;&gt;Full Text Search Engine&lt;a class=&quot;zola-anchor&quot; href=&quot;#full-text-search-engine&quot; aria-label=&quot;Anchor link for: full-text-search-engine&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h1&gt;
&lt;p&gt;Suppose you are building an online store and you want to give to customers an ability to search against goods.&lt;br &#x2F;&gt;
How are you going to implement it?&lt;&#x2F;p&gt;
&lt;h2 id=&quot;preparations&quot;&gt;Preparations&lt;a class=&quot;zola-anchor&quot; href=&quot;#preparations&quot; aria-label=&quot;Anchor link for: preparations&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h2&gt;
&lt;p&gt;Let&#x27;s implement a stupid page where our potential user searches.&lt;&#x2F;p&gt;
&lt;p&gt;Firstly, let&#x27;s install all needed packages for that.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo install wasm-pack          &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# Compile Rust to Wasm and generate JS interop code
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo install cargo-make         &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# Task runner
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add wasm-bindgen           &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# glue for Rust -&amp;gt; WASM, WASM &amp;lt;- Rust
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add yew                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# Rust -&amp;gt; Wasm frontend framework
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add instant                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# needs for request&amp;#39;s time measurement
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add http                   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# make requests from ui
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add serde                  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# [de]serialization
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add serde_json             &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# json [de]serialization
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add anyhow                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# flexible errors
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add rocket                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# server framework
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add rocket-contrib         &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# useful things for rocket such as static serving
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add csv                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# parse csv files
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add regex                  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# -..-
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now lets open &lt;strong&gt;Cargo.toml&lt;&#x2F;strong&gt; file and modify it a little bit:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;toml&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-toml &quot;&gt;&lt;code class=&quot;language-toml&quot; data-lang=&quot;toml&quot;&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;lib&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;crate-type &lt;&#x2F;span&gt;&lt;span&gt;= [&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;cdylib&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;rlib&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;]    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# for WASM
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;name &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;myox_ftse_lib&amp;quot;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;path &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;src&#x2F;lib.rs&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;[[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;bin&lt;&#x2F;span&gt;&lt;span&gt;]]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;name &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;myox_ftse&amp;quot;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;path &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;src&#x2F;bin.rs&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# [dependencies]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# time measurement in WASM
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;instant &lt;&#x2F;span&gt;&lt;span&gt;= { &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;version &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;0.1.6&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;features &lt;&#x2F;span&gt;&lt;span&gt;= [ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;wasm-bindgen&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;now&amp;quot; &lt;&#x2F;span&gt;&lt;span&gt;] }&lt;&#x2F;span&gt;&lt;span style=&quot;background-color:#562d56bf;color:#f8f8f8;&quot;&gt; &lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;The second step is to create a job which will be used for UI building.
Lets create a &lt;strong&gt;Makefile.toml&lt;&#x2F;strong&gt; in the project root(it was token from the perfect article: &lt;a href=&quot;http:&#x2F;&#x2F;www.sheshbabu.com&#x2F;posts&#x2F;rust-wasm-yew-single-page-application&#x2F;&quot;&gt;introduction into yew&lt;&#x2F;a&gt;):&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;toml&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-toml &quot;&gt;&lt;code class=&quot;language-toml&quot; data-lang=&quot;toml&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# Every change in our code will trigger ui project rebuilding
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# so that we don&amp;#39;t need to do it manually.
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;# All asssets will be stored in myox_ftse&#x2F;static&#x2F;
&lt;&#x2F;span&gt;&lt;span&gt;[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#6486ab;&quot;&gt;tasks.build&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;command &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;wasm-pack&amp;quot;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;args &lt;&#x2F;span&gt;&lt;span&gt;= [&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;build&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;--dev&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;--target&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;web&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;--out-name&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;wasm&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;--out-dir&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;static&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;watch &lt;&#x2F;span&gt;&lt;span&gt;= { &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f902a;&quot;&gt;ignore_pattern &lt;&#x2F;span&gt;&lt;span&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;static&#x2F;*&amp;quot; &lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;h1 id=&quot;let-s-code-a-ui&quot;&gt;Let&#x27;s code a UI&lt;a class=&quot;zola-anchor&quot; href=&quot;#let-s-code-a-ui&quot; aria-label=&quot;Anchor link for: let-s-code-a-ui&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h1&gt;
&lt;p&gt;All ui will be stored in the single(ui.rs) file.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lib.rs
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;ui&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;I won&#x27;t give many comments about UI part, there is a great article about that which was mentioned earlier and I recommend to read it.&lt;br &#x2F;&gt;
Conceptually, let&#x27;s have 2 forms which at the same time send requests to a server with a search query. Additionally let&#x27;s measure a time which is needed to get responses back, because we all like numbers but not a row info, isn&#x27;t it?&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;ui.rs
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;anyhow::Error;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;http::{Request, Response};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;serde_json::json;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;wasm_bindgen::prelude::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;yew::format::Json;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;yew::prelude::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;yew::services::{fetch::FetchTask, ConsoleService, FetchService};
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Model &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;link&lt;&#x2F;span&gt;&lt;span&gt;: ComponentLink&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;search_value&lt;&#x2F;span&gt;&lt;span&gt;: String,
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; this values are used for requests time measurements
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;requests_start_time&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;f64&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;request_time_slow_diff_secs&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;f64&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;request_time_fast_diff_secs&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;f64&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; found items to render
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;found_items_slow&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;found_items_fast&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;	
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; in order to not drop and as a consequence abort our requests
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; we store them
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;requests&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Option&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;FetchTask&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub enum &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Msg &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    Lookup(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;),
&lt;&#x2F;span&gt;&lt;span&gt;    FoundSlow(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;),
&lt;&#x2F;span&gt;&lt;span&gt;    FoundFast(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;),
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl &lt;&#x2F;span&gt;&lt;span&gt;Component &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Model &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;type &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Message &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; Msg;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;type &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Properties &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;create&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self::&lt;&#x2F;span&gt;&lt;span&gt;Properties, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;link&lt;&#x2F;span&gt;&lt;span&gt;: ComponentLink&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            link,
&lt;&#x2F;span&gt;&lt;span&gt;            search_value: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_owned&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;            requests: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;None&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;            requests_start_time: instant::now(),
&lt;&#x2F;span&gt;&lt;span&gt;            request_time_slow_diff_secs: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0.0&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;            request_time_fast_diff_secs: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0.0&lt;&#x2F;span&gt;&lt;span&gt;,
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;            found_items_slow: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[],
&lt;&#x2F;span&gt;&lt;span&gt;            found_items_fast: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[],
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;update&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;msg&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self::&lt;&#x2F;span&gt;&lt;span&gt;Message) -&amp;gt; ShouldRender {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;match&lt;&#x2F;span&gt;&lt;span&gt; msg {
&lt;&#x2F;span&gt;&lt;span&gt;            Msg::Lookup(v) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.search_value &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; v.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; body &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;json!&lt;&#x2F;span&gt;&lt;span&gt;({ &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;text&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;: v });
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; request_slow &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Request::post(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;goods&#x2F;lookup_slow&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;body&lt;&#x2F;span&gt;&lt;span&gt;(Json(body))
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;slow request was sent&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; request_fast &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Request::post(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;goods&#x2F;lookup_fast&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;body&lt;&#x2F;span&gt;&lt;span&gt;(Json(body))
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;fast request was sent&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; slow_request &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;FetchService::fetch(
&lt;&#x2F;span&gt;&lt;span&gt;                    request_slow,
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.link
&lt;&#x2F;span&gt;&lt;span&gt;                        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;callback&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;response&lt;&#x2F;span&gt;&lt;span&gt;: Response&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, Error&amp;gt;&amp;gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;                            ConsoleService::log(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:?}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, response));
&lt;&#x2F;span&gt;&lt;span&gt;                            Msg::FoundSlow(
&lt;&#x2F;span&gt;&lt;span&gt;                                serde_json::from_slice(
&lt;&#x2F;span&gt;&lt;span&gt;                                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;response.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;body&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_ref&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_bytes&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                                )
&lt;&#x2F;span&gt;&lt;span&gt;                                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;                            )
&lt;&#x2F;span&gt;&lt;span&gt;                        }),
&lt;&#x2F;span&gt;&lt;span&gt;                )
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;slow fetch was not completed&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; fast_request &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;FetchService::fetch(
&lt;&#x2F;span&gt;&lt;span&gt;                    request_fast,
&lt;&#x2F;span&gt;&lt;span&gt;                    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.link
&lt;&#x2F;span&gt;&lt;span&gt;                        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;callback&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;response&lt;&#x2F;span&gt;&lt;span&gt;: Response&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, Error&amp;gt;&amp;gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;                            ConsoleService::log(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:?}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, response.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;body&lt;&#x2F;span&gt;&lt;span&gt;()));
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; Msg::FoundFast(
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     serde_json::from_slice(
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;         &amp;amp;response.body().as_ref().unwrap().as_bytes(),
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     )
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     .unwrap(),
&lt;&#x2F;span&gt;&lt;span&gt;                            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; )
&lt;&#x2F;span&gt;&lt;span&gt;                            Msg::FoundFast(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[])
&lt;&#x2F;span&gt;&lt;span&gt;                        }),
&lt;&#x2F;span&gt;&lt;span&gt;                )
&lt;&#x2F;span&gt;&lt;span&gt;                .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;fast fetch was not completed&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.requests &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Some&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[slow_request, fast_request]);
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.requests_start_time &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;instant::now();
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;            Msg::FoundSlow(items) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.found_items_slow &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; items;
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.request_time_slow_diff_secs &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=
&lt;&#x2F;span&gt;&lt;span&gt;                    (instant::now() &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.requests_start_time) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&#x2F; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1000.0&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;            Msg::FoundFast(items) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.found_items_slow &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; items;
&lt;&#x2F;span&gt;&lt;span&gt;				&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; useless for now
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; self.request_time_fast_diff_secs =
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;    (instant::now() - self.requests_start_time) &#x2F; 1000.0;
&lt;&#x2F;span&gt;&lt;span&gt;            }
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;true
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;change&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;_&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;Self::&lt;&#x2F;span&gt;&lt;span&gt;Properties) -&amp;gt; ShouldRender {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;true
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;view&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; Html {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;html! &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;div class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;forms&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;div class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;slow&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        {&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_slow_form&lt;&#x2F;span&gt;&lt;span&gt;()}
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;div&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;div class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;fast&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        {&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get_fast_form&lt;&#x2F;span&gt;&lt;span&gt;()}
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;div&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;div&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;impl &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Model &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_slow_form&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; Html {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;html! &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;div class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;form&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;h2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;Request time: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:.3}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;s&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.request_time_slow_diff_secs)}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;h2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;input
&lt;&#x2F;span&gt;&lt;span&gt;                     class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;new-todo&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;                     placeholder&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;What are we are looking for?&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;                     value&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.search_value
&lt;&#x2F;span&gt;&lt;span&gt;                     oninput&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.link.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;callback&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;: InputData| Msg::Lookup(e.value))
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&#x2F;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;ul class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;found-items&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.found_items_slow.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;html! &lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;span&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, i)}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;span&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;})}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;ul&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;div&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;get_fast_form&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; Html {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;html! &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;div class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;form&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;h2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;Request time: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{:.3}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;s&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.request_time_fast_diff_secs )}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;h2&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;input
&lt;&#x2F;span&gt;&lt;span&gt;                     class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;new-todo&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;                     placeholder&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;What are we are looking for?&amp;quot;
&lt;&#x2F;span&gt;&lt;span&gt;                     value&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.search_value
&lt;&#x2F;span&gt;&lt;span&gt;                     oninput&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.link.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;callback&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;e&lt;&#x2F;span&gt;&lt;span&gt;: InputData| Msg::Lookup(e.value))
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&#x2F;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;                 &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;ul class&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;found-items&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.found_items_fast.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;html! &lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span&gt;span&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;{&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, i)}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;span&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;&lt;&#x2F;span&gt;&lt;span&gt;})}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;ul&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;            &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;lt;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt;div&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;gt;
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;wasm_bindgen&lt;&#x2F;span&gt;&lt;span&gt;(start)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;run_app&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    App::&amp;lt;Model&amp;gt;::new().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;mount_to_body&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;h1 id=&quot;server&quot;&gt;Server&lt;a class=&quot;zola-anchor&quot; href=&quot;#server&quot; aria-label=&quot;Anchor link for: server&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h1&gt;
&lt;p&gt;In order to search goods by descriptions we need descriptions.&lt;br &#x2F;&gt;
I found &lt;a href=&quot;https:&#x2F;&#x2F;www.kaggle.com&#x2F;sachsene&#x2F;amazons-advertisements&#x2F;data&quot;&gt;this one&lt;&#x2F;a&gt;.
Download and place it in project&#x27;s root(if you want).&lt;br &#x2F;&gt;
Descriptions are stored in &lt;a href=&quot;https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Comma-separated_values&quot;&gt;csv&lt;&#x2F;a&gt;, so firstly we need to parse them:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lib.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;parse_csv&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::error::Error;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;parse_csv&lt;&#x2F;span&gt;&lt;span&gt;() -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Result&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, String)&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Box&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;dyn Error&amp;gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; wiki &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;std::io::BufReader::new(
&lt;&#x2F;span&gt;&lt;span&gt;        std::fs::File::open(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;amazon_combined_scrapped_data.csv&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;    );
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; descriptions &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; rdr &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;csv::Reader::from_reader(wiki);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for &lt;&#x2F;span&gt;&lt;span&gt;(i, result) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;in&lt;&#x2F;span&gt;&lt;span&gt; rdr.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;records&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;enumerate&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; record &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; result&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;?&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;for&lt;&#x2F;span&gt;&lt;span&gt; f &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;in&lt;&#x2F;span&gt;&lt;span&gt; record.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;            descriptions.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;((i, f.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;()));
&lt;&#x2F;span&gt;&lt;span&gt;        }
&lt;&#x2F;span&gt;&lt;span&gt;    }
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Ok&lt;&#x2F;span&gt;&lt;span&gt;(descriptions)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;So now with that function we can get a vector of goods descriptions.&lt;br &#x2F;&gt;
The last part is a server itself:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lib.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;server&lt;&#x2F;span&gt;&lt;span&gt;.rs
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;server.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;rocket::{post, routes, State};
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; get and send JSON&amp;#39;s
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;rocket_contrib::json;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;rocket_contrib::json::Json;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;rocket_contrib::json::JsonValue;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; serves our static assets for UI
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;rocket_contrib::serve::StaticFiles;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; deserializes JSON bodies from UI
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;serde::Deserialize;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use crate&lt;&#x2F;span&gt;&lt;span&gt;::parse_csv;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; server&amp;#39;s shared state
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; basically it&amp;#39;s descriptions vector of goods which we sell =)
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Store &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;goods&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; this funciton is used for our server bootstraping
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;run_server&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; parsed goods descritpions
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; items &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;parse_csv::parse_csv().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    rocket::ignite()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;manage&lt;&#x2F;span&gt;&lt;span&gt;(Store { goods: items })
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; serves static files which are placed in myox_ftse&#x2F;static&#x2F;
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;mount&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, StaticFiles::from(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;static&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;))
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; there will be two routes:
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; the first for slow requests serving
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; the second one for fast requests serving
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; currently only slow requests serving is implemented
&lt;&#x2F;span&gt;&lt;span&gt;        &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; fast part will be implemented incrementally
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;mount&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;goods&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;routes!&lt;&#x2F;span&gt;&lt;span&gt;[lookup_slow, lookup_fast])
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;launch&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;rocket&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;post&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;lookup_slow&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, data &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;lt;search_text&amp;gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;lookup_slow&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;state&lt;&#x2F;span&gt;&lt;span&gt;: State&amp;lt;Store&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;search_text&lt;&#x2F;span&gt;&lt;span&gt;: Json&amp;lt;Search&amp;gt;) -&amp;gt; JsonValue {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; obj &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; search_text.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_inner&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; re &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;regex::Regex::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\\&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;b&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}\\&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;b&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, obj.text)).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; found: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; state
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;inner&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .goods
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;filter&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;item&lt;&#x2F;span&gt;&lt;span&gt;| item.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;find&lt;&#x2F;span&gt;&lt;span&gt;(obj.text.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_some&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;v&lt;&#x2F;span&gt;&lt;span&gt;| v.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;json!&lt;&#x2F;span&gt;&lt;span&gt;(found)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;rocket&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;post&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;lookup_fast&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, data &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;lt;search_text&amp;gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;lookup_fast&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;state&lt;&#x2F;span&gt;&lt;span&gt;: State&amp;lt;Store&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;search_text&lt;&#x2F;span&gt;&lt;span&gt;: Json&amp;lt;Search&amp;gt;) -&amp;gt; JsonValue {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; v: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;json!&lt;&#x2F;span&gt;&lt;span&gt;(v)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Finnaly let&#x27;s bootstrap it!&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;bin.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;main&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    myox_ftse_lib::server::run_server();
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now open a terminal and in project&#x27;s root type:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;&#x2F;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt; for ui rebuildings
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo make build
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Open the second terminal and type there: &lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;&#x2F;&#x2F;&lt;&#x2F;span&gt;&lt;span&gt; start a server
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo run
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;myox_ftse_slow_request_good.png&quot; alt=&quot;slow requests results good&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;Not so bad.&lt;br &#x2F;&gt;
After some time customer comes back and says that it&#x27;s inconvenient to scroll through things which are useless.&lt;br &#x2F;&gt;
Take a look: we searched &lt;strong&gt;rust&lt;&#x2F;strong&gt; but there are results which are just substrings but not a word what we are looking for: 
&lt;img src=&quot;..&#x2F;myox_ftse_slow_request_bad.png&quot; alt=&quot;slow request results bad&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;Ok, how we can fix it? Probably rexeges can help us. Let&#x27;s give it a try!&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;server.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;rocket&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;post&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;lookup_slow&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, data &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;lt;search_text&amp;gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;lookup_slow&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;state&lt;&#x2F;span&gt;&lt;span&gt;: State&amp;lt;Store&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;search_text&lt;&#x2F;span&gt;&lt;span&gt;: Json&amp;lt;Search&amp;gt;) -&amp;gt; JsonValue {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; obj &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; search_text.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_inner&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; re &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;regex::Regex::new(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;\\&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;b&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}\\&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;b&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, obj.text)).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; found: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; state
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;inner&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .goods
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-       &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;filter&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;item&lt;&#x2F;span&gt;&lt;span&gt;| item.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;find&lt;&#x2F;span&gt;&lt;span&gt;(obj.text.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_some&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+       &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;filter&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;item&lt;&#x2F;span&gt;&lt;span&gt;| re.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_match&lt;&#x2F;span&gt;&lt;span&gt;(item.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;()))
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;v&lt;&#x2F;span&gt;&lt;span&gt;| v.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;json!&lt;&#x2F;span&gt;&lt;span&gt;(found)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Let&#x27;s take a look:&lt;&#x2F;p&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;myox_ftse_slow_request_ugly.png&quot; alt=&quot;slow request results ugly&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;The good news - the problem solved. The bad news - the customer won&#x27;t wait so much time.&lt;br &#x2F;&gt;
Can we do better? Yes, we can!&lt;&#x2F;p&gt;
&lt;h1 id=&quot;inverted-index-full-text-search-engines-etc&quot;&gt;Inverted Index, Full Text Search Engines, etc&lt;a class=&quot;zola-anchor&quot; href=&quot;#inverted-index-full-text-search-engines-etc&quot; aria-label=&quot;Anchor link for: inverted-index-full-text-search-engines-etc&quot;&gt;🔗&lt;&#x2F;a&gt;&lt;&#x2F;h1&gt;
&lt;p&gt;The key idea is find a suitable data structure which will be used for searching. You&#x27;ve probably seen in readed books a page which shows a word and pages which contain this word. And that&#x27;s it.&lt;br &#x2F;&gt;
In a more detail: there are o lot of texts. We want to search against them. Let&#x27;s read all documents and save a word with corresponded document id. When searching - make a lookup against all words, find corresponded documents and retrieve them.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;inverted_index.png&quot; alt=&quot;inverted index&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;An attentive reader will notice that not all words after texts processing stored in the table. Futhermore they have a different form.&lt;br &#x2F;&gt;
Indeed there are words which are often used and kind of useless: &lt;strong&gt;and, or, the&lt;&#x2F;strong&gt;, etc.&lt;br &#x2F;&gt;
Punctuation marks are also not super usefull.&lt;br &#x2F;&gt;
Let&#x27;s consider &lt;strong&gt;Rust&lt;&#x2F;strong&gt; and &lt;strong&gt;rust&lt;&#x2F;strong&gt; words: they have the same semantics(in the sense of the word meaning) but they are not equal -&amp;gt; let&#x27;s make them lowercased.&lt;br &#x2F;&gt;
Let&#x27;s consider &lt;strong&gt;cars&lt;&#x2F;strong&gt; and &lt;strong&gt;car&lt;&#x2F;strong&gt;: these both are also about the same, but one plural, the other one not. Let&#x27;s also get rid of such cases and store only one word in its initial form.&lt;&#x2F;p&gt;
&lt;p&gt;This all happens in this green block. Let&#x27;s unwrap it.&lt;&#x2F;p&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;myox_ftse_slow_linguistic_modules.png&quot; alt=&quot;linguistic modules&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;&lt;strong&gt;Tokenizer&lt;&#x2F;strong&gt; gets input and splits it into lexemes. &lt;strong&gt;Linguistic modules&lt;&#x2F;strong&gt; preprocess them before they trap into &lt;strong&gt;indexer&lt;&#x2F;strong&gt; which stores them.&lt;&#x2F;p&gt;
&lt;p&gt;I hope that now you understand a key idea. Let&#x27;s code it.&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lib.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;tokenizer&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;lingua&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;tokenizer.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;tokenize&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;s&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;str&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    s.split::&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;char&lt;&#x2F;span&gt;&lt;span&gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;bool&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;l&lt;&#x2F;span&gt;&lt;span&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;!&lt;&#x2F;span&gt;&lt;span&gt;l.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;is_alphabetic&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;v&lt;&#x2F;span&gt;&lt;span&gt;| v.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lingua.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; this function is basically a pipeline of linguistic modules
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;preprocess&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, String)&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, String)&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;todo!&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;to_lower_case&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    tokens
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ts&lt;&#x2F;span&gt;&lt;span&gt;)| (&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;i, ts.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;s&lt;&#x2F;span&gt;&lt;span&gt;| s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_lowercase&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;()))
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Next we need to remove all &amp;quot;useless&amp;quot;(stopwords) words. There are different sources which make analysis and can provide such info.&lt;br &#x2F;&gt;
We will use the crate called &lt;strong&gt;stopwords&lt;&#x2F;strong&gt; as well as &lt;strong&gt;lazy_static&lt;&#x2F;strong&gt; for storing these words:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add stopwords
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;cargo&lt;&#x2F;span&gt;&lt;span&gt; add lazy_static
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lingua.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;lazy_static::lazy_static&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;! &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;static ref &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;STOPWORDS&lt;&#x2F;span&gt;&lt;span&gt;: HashSet&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;&amp;#39;static str&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Spark::stopwords(Language::English)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;v&lt;&#x2F;span&gt;&lt;span&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;v)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;remove_stopwords&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mut &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    tokens
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter_mut&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;for_each&lt;&#x2F;span&gt;&lt;span&gt;(|(_, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ts&lt;&#x2F;span&gt;&lt;span&gt;)| ts.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;retain&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;s&lt;&#x2F;span&gt;&lt;span&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;!&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;STOPWORDS&lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;contains&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;())));
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    tokens
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Next let&#x27;s normalize words. This process is called &lt;strong&gt;stemming&lt;&#x2F;strong&gt;:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;bash&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-bash &quot;&gt;&lt;code class=&quot;language-bash&quot; data-lang=&quot;bash&quot;&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;$&lt;&#x2F;span&gt;&lt;span&gt; cargo add rust-stemmers
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lingua.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;rust_stemmers::{Algorithm, Stemmer};
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;normalize&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; en_stemmer &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;Stemmer::create(Algorithm::English);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    tokens
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ts&lt;&#x2F;span&gt;&lt;span&gt;)| {
&lt;&#x2F;span&gt;&lt;span&gt;            (
&lt;&#x2F;span&gt;&lt;span&gt;                &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;i,
&lt;&#x2F;span&gt;&lt;span&gt;                ts.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;s&lt;&#x2F;span&gt;&lt;span&gt;| en_stemmer.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;stem&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;()).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;to_string&lt;&#x2F;span&gt;&lt;span&gt;())
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span&gt;            )
&lt;&#x2F;span&gt;&lt;span&gt;        })
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Finnally, let&#x27;s compose this processors:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;preprocess&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;tokens&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt;) -&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt; {
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;todo!&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+    &lt;&#x2F;span&gt;&lt;span&gt;[to_lower_case, remove_stopwords, normalize]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+        &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+        &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;fold&lt;&#x2F;span&gt;&lt;span&gt;(tokens, |&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;transformed&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;processor&lt;&#x2F;span&gt;&lt;span&gt;| &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;processor&lt;&#x2F;span&gt;&lt;span&gt;(transformed))
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Now we need to store processed values:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;lib.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; --&#x2F;&#x2F;--
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;mod &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;indexer&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;indexer.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;use &lt;&#x2F;span&gt;&lt;span&gt;std::collections::{HashMap, HashSet};
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;index&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;vocabulary&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;)&amp;gt;) -&amp;gt; HashMap&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, HashSet&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt; {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; inv_index: HashMap&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, HashSet&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;HashMap::new();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    vocabulary.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;for_each&lt;&#x2F;span&gt;&lt;span&gt;(|(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ts&lt;&#x2F;span&gt;&lt;span&gt;)| {
&lt;&#x2F;span&gt;&lt;span&gt;        ts.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;for_each&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;s&lt;&#x2F;span&gt;&lt;span&gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;            inv_index.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;entry&lt;&#x2F;span&gt;&lt;span&gt;(s).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;or_default&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;insert&lt;&#x2F;span&gt;&lt;span&gt;(i);
&lt;&#x2F;span&gt;&lt;span&gt;        });
&lt;&#x2F;span&gt;&lt;span&gt;    });
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    inv_index
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;We near the finish. Let&#x27;s add a fast lookup variant to our API:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;server.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;struct &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;Store &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;goods&lt;&#x2F;span&gt;&lt;span&gt;: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, String)&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;+   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;indexed_goods&lt;&#x2F;span&gt;&lt;span&gt;: std::collections::HashMap&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;, std::collections::HashSet&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt;&amp;gt;,
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;pub fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;run_server&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; now &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;std::time::Instant::now();
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; items &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span&gt;parse_csv::parse_csv().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; indexed_goods &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= crate&lt;&#x2F;span&gt;&lt;span&gt;::indexer::index(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;crate&lt;&#x2F;span&gt;&lt;span&gt;::lingua::preprocess(
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;       items
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+           &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+           &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;()
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+           &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;i&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;s&lt;&#x2F;span&gt;&lt;span&gt;)| (&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;i, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;crate&lt;&#x2F;span&gt;&lt;span&gt;::tokenizer::tokenize(s.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_str&lt;&#x2F;span&gt;&lt;span&gt;())))
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+           &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;collect&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+   &lt;&#x2F;span&gt;&lt;span&gt;));
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;println!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;Parsing time: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, now.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;elapsed&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_secs&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;println!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;Items count: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, items.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;len&lt;&#x2F;span&gt;&lt;span&gt;());
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    rocket::ignite()
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;manage&lt;&#x2F;span&gt;&lt;span&gt;(Store {
&lt;&#x2F;span&gt;&lt;span&gt;            goods: items,
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+&lt;&#x2F;span&gt;&lt;span&gt;           indexed_goods,
&lt;&#x2F;span&gt;&lt;span&gt;        })
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;mount&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, StaticFiles::from(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;.&#x2F;static&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;))
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;mount&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;goods&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;routes!&lt;&#x2F;span&gt;&lt;span&gt;[lookup_slow, lookup_fast])
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;launch&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;#[&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;rocket&lt;&#x2F;span&gt;&lt;span&gt;::&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;post&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&#x2F;lookup_fast&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, data &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;&amp;lt;search_text&amp;gt;&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)]
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;lookup_fast&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;state&lt;&#x2F;span&gt;&lt;span&gt;: State&amp;lt;Store&amp;gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;search_text&lt;&#x2F;span&gt;&lt;span&gt;: Json&amp;lt;Search&amp;gt;) -&amp;gt; JsonValue {
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; v: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;String&lt;&#x2F;span&gt;&lt;span&gt;&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-   &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;json!&lt;&#x2F;span&gt;&lt;span&gt;(v)
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; obj &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; search_text.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;into_inner&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; goods: &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;Vec&lt;&#x2F;span&gt;&lt;span&gt;&amp;lt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;usize&lt;&#x2F;span&gt;&lt;span&gt;, String)&amp;gt; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; state.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;inner&lt;&#x2F;span&gt;&lt;span&gt;().goods.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_ref&lt;&#x2F;span&gt;&lt;span&gt;();
&lt;&#x2F;span&gt;&lt;span&gt;	
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; weird =(, but less code
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; pp_query &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= crate&lt;&#x2F;span&gt;&lt;span&gt;::lingua::preprocess(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;, &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[obj.text.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;clone&lt;&#x2F;span&gt;&lt;span&gt;()])]);
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let&lt;&#x2F;span&gt;&lt;span&gt; preprocessed_text &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; pp_query
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;valid search text&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;0&lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;        .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;query shouldn&amp;#39;t be deleted&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;let mut&lt;&#x2F;span&gt;&lt;span&gt; res &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;= &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[];
&lt;&#x2F;span&gt;&lt;span&gt;    state.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;inner&lt;&#x2F;span&gt;&lt;span&gt;().indexed_goods.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;obj.text).&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;map&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;ids&lt;&#x2F;span&gt;&lt;span&gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;        ids.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;iter&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;for_each&lt;&#x2F;span&gt;&lt;span&gt;(|&lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;id&lt;&#x2F;span&gt;&lt;span&gt;| {
&lt;&#x2F;span&gt;&lt;span&gt;            res.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;push&lt;&#x2F;span&gt;&lt;span&gt;(
&lt;&#x2F;span&gt;&lt;span&gt;                goods
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;get&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;*&lt;&#x2F;span&gt;&lt;span&gt;id)
&lt;&#x2F;span&gt;&lt;span&gt;                    .&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;expect&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&amp;amp;&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;format!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;doc with id=&lt;&#x2F;span&gt;&lt;span style=&quot;color:#aeb52b;&quot;&gt;{}&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt; should be presented&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;, id)),
&lt;&#x2F;span&gt;&lt;span&gt;            )
&lt;&#x2F;span&gt;&lt;span&gt;        })
&lt;&#x2F;span&gt;&lt;span&gt;    });
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;json!&lt;&#x2F;span&gt;&lt;span&gt;(res)
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;In order to see &amp;quot;fast&amp;quot; requests results we also need to modify UI:&lt;&#x2F;p&gt;
&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; src&#x2F;ui.rs
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; in fn update():
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; disabled for a while
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; Msg::FoundFast(
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     serde_json::from_slice(
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;         &amp;amp;response.body().as_ref().unwrap().as_bytes(),
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     )
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     .unwrap(),
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; )
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span&gt;Msg::FoundFast(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;vec!&lt;&#x2F;span&gt;&lt;span&gt;[])
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+ &lt;&#x2F;span&gt;&lt;span&gt;Msg::FoundFast(
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+     &lt;&#x2F;span&gt;&lt;span&gt;serde_json::from_slice(
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+         &amp;amp;&lt;&#x2F;span&gt;&lt;span&gt;response.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;body&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_ref&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;().&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;as_bytes&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+     &lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+     &lt;&#x2F;span&gt;&lt;span&gt;.&lt;&#x2F;span&gt;&lt;span style=&quot;color:#b39f04;&quot;&gt;unwrap&lt;&#x2F;span&gt;&lt;span&gt;(),
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+ &lt;&#x2F;span&gt;&lt;span&gt;)
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span&gt;Msg::FoundFast(items) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&amp;gt; &lt;&#x2F;span&gt;&lt;span&gt;{
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.found_items_slow &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; items;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F; self.request_time_fast_diff_secs =
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;-    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#7f8989;&quot;&gt;&#x2F;&#x2F;     (instant::now() - self.requests_start_time) &#x2F; 1000.0;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.found_items_fast &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=&lt;&#x2F;span&gt;&lt;span&gt; items;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+    &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.request_time_fast_diff_secs &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;=
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;+	     &lt;&#x2F;span&gt;&lt;span&gt;(instant::now() &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;- &lt;&#x2F;span&gt;&lt;span style=&quot;color:#5597d6;&quot;&gt;self&lt;&#x2F;span&gt;&lt;span&gt;.requests_start_time) &lt;&#x2F;span&gt;&lt;span style=&quot;color:#72ab00;&quot;&gt;&#x2F; &lt;&#x2F;span&gt;&lt;span style=&quot;color:#b3933a;&quot;&gt;1000.0&lt;&#x2F;span&gt;&lt;span&gt;;
&lt;&#x2F;span&gt;&lt;span&gt;     }
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
&lt;p&gt;Run our query again: &lt;&#x2F;p&gt;
&lt;p&gt;&lt;img src=&quot;..&#x2F;myox_ftse_fast.png&quot; alt=&quot;fast request&quot; &#x2F;&gt;&lt;&#x2F;p&gt;
&lt;p&gt;Cool!&lt;&#x2F;p&gt;
&lt;p&gt;There are a lot of other questions:&lt;&#x2F;p&gt;
&lt;ul&gt;
&lt;li&gt;how to persist indexes&lt;&#x2F;li&gt;
&lt;li&gt;how to rank results&lt;&#x2F;li&gt;
&lt;li&gt;how to query against complex phrases&lt;&#x2F;li&gt;
&lt;li&gt;different types of docs indexing&lt;&#x2F;li&gt;
&lt;li&gt;possibility to handle multiple languages&lt;&#x2F;li&gt;
&lt;li&gt;etc&lt;&#x2F;li&gt;
&lt;&#x2F;ul&gt;
&lt;p&gt;Maybe I&#x27;ll come back to this questions in the future, but i think it&#x27;s enough for now.&lt;&#x2F;p&gt;
&lt;p&gt;I hope that this was usefull!&lt;br &#x2F;&gt;
Good luck!&lt;&#x2F;p&gt;
</description>
      </item>
      <item>
          <title>MYOX: what does it mean?</title>
          <pubDate>Mon, 29 Jun 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/myox/</link>
          <guid>https://kakoc.blog/blog/myox/</guid>
          <description>&lt;p&gt;It was always hard for me to use some thing(only in a programming world =) ) without understanding how actually this thing works. Someone can say that it&#x27;s actually a problem and it&#x27;s hard to develop complex things without such skill. But based on my experience exceptions are present everywhere. And everybody has it. What should we be able to do is take our &amp;quot;disadvantages&amp;quot; and turn them into advantages. I won&#x27;t show you many examples of it, just left the most appropriate person to this context:&lt;&#x2F;p&gt;
&lt;blockquote&gt;
&lt;p&gt;&amp;quot;What I cannot create, I do not understand&amp;quot; - Richard Feynman&lt;&#x2F;p&gt;
&lt;&#x2F;blockquote&gt;
&lt;p&gt;So in MYOX series I&#x27;ll demonstrate fundamentals behind things which I wanted to understand.&lt;&#x2F;p&gt;
&lt;p&gt;All things I&#x27;ll implement with Rust programming language since I think that Rust is a next big thing in programming languages world as well as in software products and we need to expand its areas as wide as we can.&lt;&#x2F;p&gt;
</description>
      </item>
      <item>
          <title>Hello, blog!</title>
          <pubDate>Sun, 28 Jun 2020 00:00:00 +0000</pubDate>
          <author>Unknown</author>
          <link>https://kakoc.blog/blog/hello-blog/</link>
          <guid>https://kakoc.blog/blog/hello-blog/</guid>
          <description>&lt;pre data-lang=&quot;rust&quot; style=&quot;background-color:#f5f5f5;color:#1f1f1f;&quot; class=&quot;language-rust &quot;&gt;&lt;code class=&quot;language-rust&quot; data-lang=&quot;rust&quot;&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;span style=&quot;color:#668f14;&quot;&gt;fn &lt;&#x2F;span&gt;&lt;span style=&quot;color:#c23f31;&quot;&gt;main&lt;&#x2F;span&gt;&lt;span&gt;() {
&lt;&#x2F;span&gt;&lt;span&gt;  &lt;&#x2F;span&gt;&lt;span style=&quot;color:#a2a001;&quot;&gt;println!&lt;&#x2F;span&gt;&lt;span&gt;(&lt;&#x2F;span&gt;&lt;span style=&quot;color:#d07711;&quot;&gt;&amp;quot;hello, blog&amp;quot;&lt;&#x2F;span&gt;&lt;span&gt;);
&lt;&#x2F;span&gt;&lt;span&gt;}
&lt;&#x2F;span&gt;&lt;span&gt;
&lt;&#x2F;span&gt;&lt;&#x2F;code&gt;&lt;&#x2F;pre&gt;
</description>
      </item>
    </channel>
</rss>