Fixes #27459: Test first/last character in match if they are word separators...

Fixes #27459: Test first/last character in match if they are word separators besides the before/after characters

src/vs/editor/common/model/textModelSearch.ts

@@ -405,23 +405,57 @@ export class TextModelSearch {
 	}
 }
 
-function isValidMatch(wordSeparators: WordCharacterClassifier, text: string, textLength: number, matchStartIndex: number, matchLength: number): boolean {
+function leftIsWordBounday(wordSeparators: WordCharacterClassifier, text: string, textLength: number, matchStartIndex: number, matchLength: number): boolean {
+	if (matchStartIndex === 0) {
+		// Match starts at start of string
+		return true;
+	}
 
-	if (matchStartIndex - 1 >= 0) {
-		const charBefore = text.charCodeAt(matchStartIndex - 1);
-		if (wordSeparators.get(charBefore) === WordCharacterClass.Regular) {
-			return false;
+	const charBefore = text.charCodeAt(matchStartIndex - 1);
+	if (wordSeparators.get(charBefore) !== WordCharacterClass.Regular) {
+		// The character before the match is a word separator
+		return true;
+	}
+
+	if (matchLength > 0) {
+		const firstCharInMatch = text.charCodeAt(matchStartIndex);
+		if (wordSeparators.get(firstCharInMatch) !== WordCharacterClass.Regular) {
+			// The first character inside the match is a word separator
+			return true;
 		}
 	}
 
-	if (matchStartIndex + matchLength < textLength) {
-		const charAfter = text.charCodeAt(matchStartIndex + matchLength);
-		if (wordSeparators.get(charAfter) === WordCharacterClass.Regular) {
-			return false;
+	return false;
+}
+
+function rightIsWordBounday(wordSeparators: WordCharacterClassifier, text: string, textLength: number, matchStartIndex: number, matchLength: number): boolean {
+	if (matchStartIndex + matchLength === textLength) {
+		// Match ends at end of string
+		return true;
+	}
+
+	const charAfter = text.charCodeAt(matchStartIndex + matchLength);
+	if (wordSeparators.get(charAfter) !== WordCharacterClass.Regular) {
+		// The character after the match is a word separator
+		return true;
+	}
+
+	if (matchLength > 0) {
+		const lastCharInMatch = text.charCodeAt(matchStartIndex + matchLength - 1);
+		if (wordSeparators.get(lastCharInMatch) !== WordCharacterClass.Regular) {
+			// The last character in the match is a word separator
+			return true;
 		}
 	}
 
-	return true;
+	return false;
+}
+
+function isValidMatch(wordSeparators: WordCharacterClassifier, text: string, textLength: number, matchStartIndex: number, matchLength: number): boolean {
+	return (
+		leftIsWordBounday(wordSeparators, text, textLength, matchStartIndex, matchLength)
+		&& rightIsWordBounday(wordSeparators, text, textLength, matchStartIndex, matchLength)
+	);
 }
 
 class Searcher {

src/vs/editor/test/common/model/textModelSearch.test.ts

@@ -354,6 +354,32 @@ suite('TextModelSearch', () => {
 		);
 	});
 
+	test('issue #27459: Match whole words regression', () => {
+		assertFindMatches(
+			[
+				'this._register(this._textAreaInput.onKeyDown((e: IKeyboardEvent) => {',
+				'	this._viewController.emitKeyDown(e);',
+				'}));',
+			].join('\n'),
+			'((e: ', false, false, USUAL_WORD_SEPARATORS,
+			[
+				[1, 45, 1, 50]
+			]
+		);
+	});
+
+	test('issue #27594: Search results disappear', () => {
+		assertFindMatches(
+			[
+				'this.server.listen(0);',
+			].join('\n'),
+			'listen(', false, false, USUAL_WORD_SEPARATORS,
+			[
+				[1, 13, 1, 20]
+			]
+		);
+	});
+
 	test('findNextMatch without regex', () => {
 		let model = TextModel.createFromString('line line one\nline two\nthree');