Fix hex color detection in strings by adding lookbehind patterns (#251589)

* Initial plan for issue

* Fix hex color detection in strings by adding lookbehind patterns

Co-authored-by: aiday-mar <61460952+aiday-mar@users.noreply.github.com>

* Simplify hex color detection to only support quotes, remove other delimiters

Co-authored-by: aiday-mar <61460952+aiday-mar@users.noreply.github.com>

* polish

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: aiday-mar <61460952+aiday-mar@users.noreply.github.com>
Co-authored-by: Aiday Marlen Kyzy <amarlenkyzy@microsoft.com>

src/vs/editor/common/languages/defaultDocumentColorsComputer.ts

@@ -101,7 +101,7 @@ function _findMatches(model: IDocumentColorComputerTarget | string, regex: RegEx
 function computeColors(model: IDocumentColorComputerTarget): IColorInformation[] {
 	const result: IColorInformation[] = [];
 	// Early validation for RGB and HSL
-	const initialValidationRegex = /\b(rgb|rgba|hsl|hsla)(\([0-9\s,.\%]*\))|\s+(#)([A-Fa-f0-9]{6})\b|\s+(#)([A-Fa-f0-9]{8})\b|^(#)([A-Fa-f0-9]{6})\b|^(#)([A-Fa-f0-9]{8})\b/gm;
+	const initialValidationRegex = /\b(rgb|rgba|hsl|hsla)(\([0-9\s,.\%]*\))|^(#)([A-Fa-f0-9]{6})\b|^(#)([A-Fa-f0-9]{8})\b|(?<=['"\s])(#)([A-Fa-f0-9]{6})\b|(?<=['"\s])(#)([A-Fa-f0-9]{8})\b/gm;
 	const initialValidationMatches = _findMatches(model, initialValidationRegex);
 
 	// Potential colors have been found, validate the parameters

src/vs/editor/test/common/languages/defaultDocumentColorsComputer.test.ts

@@ -0,0 +1,102 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+import * as assert from 'assert';
+import { computeDefaultDocumentColors } from '../../../common/languages/defaultDocumentColorsComputer.js';
+import { ensureNoDisposablesAreLeakedInTestSuite } from '../../../../base/test/common/utils.js';
+
+suite('Default Document Colors Computer', () => {
+
+	class TestDocumentModel {
+		constructor(private content: string) { }
+
+		getValue(): string {
+			return this.content;
+		}
+
+		positionAt(offset: number) {
+			const lines = this.content.substring(0, offset).split('\n');
+			return {
+				lineNumber: lines.length,
+				column: lines[lines.length - 1].length + 1
+			};
+		}
+
+		findMatches(regex: RegExp): RegExpMatchArray[] {
+			return [...this.content.matchAll(regex)];
+		}
+	}
+
+	ensureNoDisposablesAreLeakedInTestSuite();
+
+	test('Hex colors in strings should be detected', () => {
+		// Test case from issue: hex color inside string is not detected
+		const model = new TestDocumentModel("const color = '#ff0000';");
+		const colors = computeDefaultDocumentColors(model);
+
+		assert.strictEqual(colors.length, 1, 'Should detect one hex color');
+		assert.strictEqual(colors[0].color.red, 1, 'Red component should be 1 (255/255)');
+		assert.strictEqual(colors[0].color.green, 0, 'Green component should be 0');
+		assert.strictEqual(colors[0].color.blue, 0, 'Blue component should be 0');
+		assert.strictEqual(colors[0].color.alpha, 1, 'Alpha should be 1');
+	});
+
+	test('Hex colors in double quotes should be detected', () => {
+		const model = new TestDocumentModel('const color = "#00ff00";');
+		const colors = computeDefaultDocumentColors(model);
+
+		assert.strictEqual(colors.length, 1, 'Should detect one hex color');
+		assert.strictEqual(colors[0].color.red, 0, 'Red component should be 0');
+		assert.strictEqual(colors[0].color.green, 1, 'Green component should be 1 (255/255)');
+		assert.strictEqual(colors[0].color.blue, 0, 'Blue component should be 0');
+	});
+
+	test('Multiple hex colors in array should be detected', () => {
+		const model = new TestDocumentModel("const colors = ['#ff0000', '#00ff00', '#0000ff'];");
+		const colors = computeDefaultDocumentColors(model);
+
+		assert.strictEqual(colors.length, 3, 'Should detect three hex colors');
+
+		// First color: red
+		assert.strictEqual(colors[0].color.red, 1, 'First color red component should be 1');
+		assert.strictEqual(colors[0].color.green, 0, 'First color green component should be 0');
+		assert.strictEqual(colors[0].color.blue, 0, 'First color blue component should be 0');
+
+		// Second color: green
+		assert.strictEqual(colors[1].color.red, 0, 'Second color red component should be 0');
+		assert.strictEqual(colors[1].color.green, 1, 'Second color green component should be 1');
+		assert.strictEqual(colors[1].color.blue, 0, 'Second color blue component should be 0');
+
+		// Third color: blue
+		assert.strictEqual(colors[2].color.red, 0, 'Third color red component should be 0');
+		assert.strictEqual(colors[2].color.green, 0, 'Third color green component should be 0');
+		assert.strictEqual(colors[2].color.blue, 1, 'Third color blue component should be 1');
+	});
+
+	test('Existing functionality should still work', () => {
+		// Test cases that were already working
+		const testCases = [
+			{ content: "const color = ' #ff0000';", name: 'hex with space before' },
+			{ content: '#ff0000', name: 'hex at start of line' },
+			{ content: '  #ff0000', name: 'hex with whitespace before' }
+		];
+
+		testCases.forEach(testCase => {
+			const model = new TestDocumentModel(testCase.content);
+			const colors = computeDefaultDocumentColors(model);
+			assert.strictEqual(colors.length, 1, `Should still detect ${testCase.name}`);
+		});
+	});
+
+	test('8-digit hex colors should also work', () => {
+		const model = new TestDocumentModel("const color = '#ff0000ff';");
+		const colors = computeDefaultDocumentColors(model);
+
+		assert.strictEqual(colors.length, 1, 'Should detect one 8-digit hex color');
+		assert.strictEqual(colors[0].color.red, 1, 'Red component should be 1');
+		assert.strictEqual(colors[0].color.green, 0, 'Green component should be 0');
+		assert.strictEqual(colors[0].color.blue, 0, 'Blue component should be 0');
+		assert.strictEqual(colors[0].color.alpha, 1, 'Alpha should be 1 (ff/255)');
+	});
+});