Merge pull request microsoft#261467 from microsoft/copilot/fix-261440

Fix KaTeX regex to prevent false math detection in PowerShell code

Author: mjbvz

src/vs/workbench/contrib/markdown/browser/markedKatexSupport.ts

@@ -169,7 +169,7 @@ export namespace MarkedKatexExtension {
 	export interface MarkedKatexOptions extends KatexOptions { }
 
 	const inlineRule = /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1(?=[\s?!\.,:'\uff1f\uff01\u3002\uff0c\uff1a']|$)/;
-	const inlineRuleNonStandard = /^(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1/; // Non-standard, even if there are no spaces before and after $ or $$, try to parse
+	const inlineRuleNonStandard = /^(?<![a-zA-Z0-9])(\${1,2})(?!\$)((?:\\.|[^\\\n])*?(?:\\.|[^\\\n\$]))\1(?![a-zA-Z0-9])/; // Non-standard, but ensure opening $ is not preceded and closing $ is not followed by word/number characters
 
 	const blockRule = /^(\${1,2})\n((?:\\[^]|[^\\])+?)\n\1(?:\n|$)/;
 
@@ -214,13 +214,10 @@ export namespace MarkedKatexExtension {
 					if (index === -1) {
 						return;
 					}
-					const f = nonStandard ? index > -1 : index === 0 || indexSrc.charAt(index - 1) === ' ';
-					if (f) {
-						const possibleKatex = indexSrc.substring(index);
 
-						if (possibleKatex.match(ruleReg)) {
-							return index;
-						}
+					const possibleKatex = indexSrc.substring(index);
+					if (possibleKatex.match(ruleReg)) {
+						return index;
 					}
 
 					indexSrc = indexSrc.substring(index + 1).replace(/^\$+/, '');

src/vs/workbench/contrib/markdown/test/browser/__snapshots__/Markdown_Katex_Support_Test_Should_not_render_math_when_dollar_sign_is_followed_by_word_character.0.snap

@@ -0,0 +1 @@
+<p>The cost is $10dollars for this item</p>

src/vs/workbench/contrib/markdown/test/browser/__snapshots__/Markdown_Katex_Support_Test_Should_not_render_math_when_dollar_sign_is_preceded_by_word_character.0.snap

@@ -0,0 +1 @@
+<p>for ($i = 1; $i -le 20; $i++) { echo "hello world"; Start-Sleep 1 }</p>

src/vs/workbench/contrib/markdown/test/browser/__snapshots__/Markdown_Katex_Support_Test_Should_still_render_math_at_start_and_end_of_line.0.snap

@@ -0,0 +1 @@
+<p><span class="katex"><span class="katex-mathml"><math><semantics><mrow><mfrac><mn>1</mn><mn>2</mn></mfrac></mrow><annotation encoding="application/x-tex">\frac{1}{2}</annotation></semantics></math></span><span class="katex-html"><span class="base"><span style="height: 1.1901em; vertical-align: -0.345em" class="strut"></span><span class="mord"><span class="mopen nulldelimiter"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span style="height: 0.8451em" class="vlist"><span style="top: -2.655em"><span style="height: 3em" class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">2</span></span></span></span><span style="top: -3.23em"><span style="height: 3em" class="pstrut"></span><span style="border-bottom-width: 0.04em" class="frac-line"></span></span><span style="top: -3.394em"><span style="height: 3em" class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">1</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span style="height: 0.345em" class="vlist"><span></span></span></span></span></span><span class="mclose nulldelimiter"></span></span></span></span></span> at start, and at end <span class="katex"><span class="katex-mathml"><math><semantics><mrow><msup><mi>x</mi><mn>2</mn></msup></mrow><annotation encoding="application/x-tex">x^2</annotation></semantics></math></span><span class="katex-html"><span class="base"><span style="height: 0.8141em" class="strut"></span><span class="mord"><span class="mord mathnormal">x</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span style="height: 0.8141em" class="vlist"><span style="top: -3.063em; margin-right: 0.05em"><span style="height: 2.7em" class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span></span></span></span></span></p>

src/vs/workbench/contrib/markdown/test/browser/__snapshots__/Markdown_Katex_Support_Test_Should_still_render_math_with_special_characters_around_dollars.0.snap

@@ -0,0 +1 @@
+<p>Hello (<span class="katex"><span class="katex-mathml"><math><semantics><mrow><mfrac><mn>1</mn><mn>2</mn></mfrac></mrow><annotation encoding="application/x-tex">\frac{1}{2}</annotation></semantics></math></span><span class="katex-html"><span class="base"><span style="height: 1.1901em; vertical-align: -0.345em" class="strut"></span><span class="mord"><span class="mopen nulldelimiter"></span><span class="mfrac"><span class="vlist-t vlist-t2"><span class="vlist-r"><span style="height: 0.8451em" class="vlist"><span style="top: -2.655em"><span style="height: 3em" class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">2</span></span></span></span><span style="top: -3.23em"><span style="height: 3em" class="pstrut"></span><span style="border-bottom-width: 0.04em" class="frac-line"></span></span><span style="top: -3.394em"><span style="height: 3em" class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight"><span class="mord mtight">1</span></span></span></span></span><span class="vlist-s">​</span></span><span class="vlist-r"><span style="height: 0.345em" class="vlist"><span></span></span></span></span></span><span class="mclose nulldelimiter"></span></span></span></span></span>) and [<span class="katex"><span class="katex-mathml"><math><semantics><mrow><msup><mi>x</mi><mn>2</mn></msup></mrow><annotation encoding="application/x-tex">x^2</annotation></semantics></math></span><span class="katex-html"><span class="base"><span style="height: 0.8141em" class="strut"></span><span class="mord"><span class="mord mathnormal">x</span><span class="msupsub"><span class="vlist-t"><span class="vlist-r"><span style="height: 0.8141em" class="vlist"><span style="top: -3.063em; margin-right: 0.05em"><span style="height: 2.7em" class="pstrut"></span><span class="sizing reset-size6 size3 mtight"><span class="mord mtight">2</span></span></span></span></span></span></span></span></span></span></span>] work fine</p>

src/vs/workbench/contrib/markdown/test/browser/markdownKatexSupport.test.ts

@@ -2,6 +2,7 @@
  *  Copyright (c) Microsoft Corporation. All rights reserved.
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
+import assert from 'assert';
 import { getWindow } from '../../../../../base/browser/dom.js';
 import { basicMarkupHtmlTags, defaultAllowedAttrs } from '../../../../../base/browser/domSanitize.js';
 import { renderMarkdown } from '../../../../../base/browser/markdownRenderer.js';
@@ -28,11 +29,13 @@ suite('Markdown Katex Support Test', () => {
 
 	test('Basic inline equation', async () => {
 		const rendered = await renderMarkdownWithKatex('Hello $\\frac{1}{2}$ World!');
+		assert.ok(rendered.element.innerHTML.includes('katex'));
 		await assertSnapshot(rendered.element.innerHTML);
 	});
 
 	test('Should support inline equation wrapped in parans', async () => {
 		const rendered = await renderMarkdownWithKatex('Hello ($\\frac{1}{2}$) World!');
+		assert.ok(rendered.element.innerHTML.includes('katex'));
 		await assertSnapshot(rendered.element.innerHTML);
 	});
 
@@ -43,6 +46,31 @@ suite('Markdown Katex Support Test', () => {
 			'\\int_{-\\infty}^{\\infty} e^{-x^2} dx = \\sqrt{\\pi}',
 			'$$',
 		].join('\n'));
+		assert.ok(rendered.element.innerHTML.includes('katex'));
+		await assertSnapshot(rendered.element.innerHTML);
+	});
+
+	test('Should not render math when dollar sign is preceded by word character', async () => {
+		const rendered = await renderMarkdownWithKatex('for ($i = 1; $i -le 20; $i++) { echo "hello world"; Start-Sleep 1 }');
+		assert.ok(!rendered.element.innerHTML.includes('katex'));
+		await assertSnapshot(rendered.element.innerHTML);
+	});
+
+	test('Should not render math when dollar sign is followed by word character', async () => {
+		const rendered = await renderMarkdownWithKatex('The cost is $10dollars for this item');
+		assert.ok(!rendered.element.innerHTML.includes('katex'));
+		await assertSnapshot(rendered.element.innerHTML);
+	});
+
+	test('Should still render math with special characters around dollars', async () => {
+		const rendered = await renderMarkdownWithKatex('Hello ($\\frac{1}{2}$) and [$x^2$] work fine');
+		assert.ok(rendered.element.innerHTML.includes('katex'));
+		await assertSnapshot(rendered.element.innerHTML);
+	});
+
+	test('Should still render math at start and end of line', async () => {
+		const rendered = await renderMarkdownWithKatex('$\\frac{1}{2}$ at start, and at end $x^2$');
+		assert.ok(rendered.element.innerHTML.includes('katex'));
 		await assertSnapshot(rendered.element.innerHTML);
 	});
 });