fix: math parsing hangs webchat (#5377)

* fix: math parsing hangs * Snaps * Changelog * Update packages/bundle/src/markdown/mathExtension/tokenizer.ts Co-authored-by: William Wong <[email protected]> * Update packages/bundle/src/markdown/mathExtension/tokenizer.ts Co-authored-by: William Wong <[email protected]> --------- Co-authored-by: William Wong <[email protected]>
microsoft · Nov 13, 2024 · f4bb6a9 · f4bb6a9
1 parent a2105fd
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -106,6 +106,7 @@ Notes: web developers are advised to use [`~` (tilde range)](https://github.com/
 -  Resolved CSS class name conflicts between component and fluent packages to prevent styling issues, in PR [#5326](https://github.com/microsoft/BotFramework-WebChat/pull/5326), in PR [#5327](https://github.com/microsoft/BotFramework-WebChat/pull/5327), by [@OEvgeny](https://github.com/OEvgeny)
 -  Fixed [#5350](https://github.com/microsoft/BotFramework-WebChat/issues/pull/5350). Bundled `shiki` in component package, in PR [#5349](https://github.com/microsoft/BotFramework-WebChat/pull5349), by [@compulim](https://github.com/compulim)
 -  Fixed modal dialog rendering to prevent visual flicker and improve UX when opening code views, in PR [#5374](https://github.com/microsoft/BotFramework-WebChat/pull/5374), by [@OEvgeny](https://github.com/OEvgeny)
+-  Fixed math parsing that could cause Web Chat to hang when processing certain LaTeX expressions, in PR [#5377](https://github.com/microsoft/BotFramework-WebChat/pull/5377), by [@OEvgeny](https://github.com/OEvgeny)
 
 # Removed
 

diff --git a/__tests__/html2/markdown/math3.html b/__tests__/html2/markdown/math3.html
@@ -91,6 +91,11 @@
 
 14. Katex syntax error:
 \[\int_0^\infty e^{-x} dx = 1 +}\]
+
+15. LLM generation error:
+\[
+\
+\]
     </x-message>
   </template>
   <main id="webchat"></main>

diff --git a/__tests__/html2/markdown/math3.html.snap-3.png b/__tests__/html2/markdown/math3.html.snap-3.png
diff --git a/packages/bundle/src/markdown/mathExtension/tokenizer.ts b/packages/bundle/src/markdown/mathExtension/tokenizer.ts
@@ -41,7 +41,7 @@ export function createTokenizer(effects: MathEffects, ok: State, nok: State) {
 
     if (code === BACKSLASH) {
       effects.consume(code);
-      return escaped;
+      return maybeCloseDelimiter;
     }
 
     effects.consume(code);
@@ -54,15 +54,14 @@ export function createTokenizer(effects: MathEffects, ok: State, nok: State) {
     return content;
   }
 
-  function escaped(code) {
+  function maybeCloseDelimiter(code: Code): State {
     if ((!isDisplay && code === CLOSE_PAREN) || (isDisplay && code === CLOSE_BRACKET)) {
       effects.consume(code);
       effects.exit('mathChunk');
       effects.exit('math');
       return ok(code);
     }
 
-    effects.consume(code);
-    return content;
+    return content(code);
   }
 }