Arithmetic working with WASM! (#188)

This is the first cut of a Rust generator, enough to run the
`fixture/arithmetic`.

Unfortunately due to mozilla/uniffi-rs#2329 not
yet released, we have to introduce a procmacro version of the fixture.

In this PR:

1. Introduce a Rust crate generator; this uses 
2. a runtime which uses typealiasing and import renaming to use
`wasm-bindgen` indirectly in the generated code.
3. the generated code needs a CallStatus to be defined in Rust; this
differs from the JSI version where the CallStatus is defined in
typescript. So the `rust-call.ts` module is made into a class with three
methods instead of three functions.
4. the generated Rust is then compiled and put through wasm-bindgen-cli
where it generates a low-level JS file.
5. the high level typescript now uses the flavor to decide whether it
uses the JSI generated typescript or the WASM, and which implementation
of the CallStatus.
6. Uses `tsx` to run the whole thing.

.github/workflows/ci.yml

@@ -73,6 +73,12 @@ jobs:
       - name: Installing
         run: cargo xtask bootstrap yarn
 
+      - name: Installing WASM
+        run: rustup target add wasm32-unknown-unknown
+
+      - name: Installing wasm-bindgen
+        run: cargo install wasm-bindgen-cli
+
       - name: Run tests of generated WASM bindings
         run: ./scripts/run-tests.sh --flavor wasm
 

crates/ubrn_bindgen/Cargo.toml

@@ -6,7 +6,7 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 [features]
 default = []
-wasm = []
+wasm = ["quote", "prettyplease", "syn", "proc-macro2"]
 
 [dependencies]
 anyhow = { workspace = true }
@@ -23,3 +23,19 @@ uniffi_meta = { workspace = true }
 extend = "1.2.0"
 topological-sort = "0.2.2"
 toml = "0.5"
+
+[dependencies.quote]
+version = "1.0"
+optional = true
+
+[dependencies.prettyplease]
+version = "0.2"
+optional = true
+
+[dependencies.syn]
+version = "2.0"
+optional = true
+
+[dependencies.proc-macro2]
+version = "1.0"
+optional = true

crates/ubrn_bindgen/src/bindings/entrypoint.rs

@@ -0,0 +1,20 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/
+ */
+use anyhow::Result;
+
+use crate::{AbiFlavor, ModuleMetadata, SwitchArgs};
+
+use super::gen_cpp;
+#[cfg(feature = "wasm")]
+use super::gen_rust;
+
+pub fn generate_entrypoint(switches: &SwitchArgs, modules: &Vec<ModuleMetadata>) -> Result<String> {
+    match &switches.flavor {
+        AbiFlavor::Jsi => gen_cpp::generate_entrypoint(modules),
+        #[cfg(feature = "wasm")]
+        AbiFlavor::Wasm => gen_rust::generate_entrypoint(modules),
+    }
+}

crates/ubrn_bindgen/src/bindings/gen_cpp/templates/wrapper.cpp

@@ -65,7 +65,7 @@ extern "C" {
 ) : callInvoker(invoker), props() {
     // Map from Javascript names to the cpp names
     {%- for func in ci.iter_ffi_functions_js_to_cpp() %}
-    {%- let name = func.name() %}
+    {%- let name = func.name()|fmt("ubrn_{}") %}
     props["{{ name }}"] = jsi::Function::createFromHostFunction(
         rt,
         jsi::PropNameID::forAscii(rt, "{{ name }}"),

crates/ubrn_bindgen/src/bindings/gen_rust/config.rs

@@ -0,0 +1,11 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/
+ */
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct RustConfig {}