Fix issue where the word definition of the right language was used for the left language

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

@@ -1742,11 +1742,41 @@ export class TextModel extends Disposable implements model.ITextModel {
 		const position = this.validatePosition(_position);
 		const lineContent = this.getLineContent(position.lineNumber);
 		const lineTokens = this._getLineTokens(position.lineNumber);
-		const offset = position.column - 1;
-		const tokenIndex = lineTokens.findTokenIndexAtOffset(offset);
+		const tokenIndex = lineTokens.findTokenIndexAtOffset(position.column - 1);
+
+		// (1). First try checking right biased word
+		const [rbStartOffset, rbEndOffset] = TextModel._findLanguageBoundaries(lineTokens, tokenIndex);
+		const rightBiasedWord = getWordAtText(
+			position.column,
+			LanguageConfigurationRegistry.getWordDefinition(lineTokens.getLanguageId(tokenIndex)),
+			lineContent.substring(rbStartOffset, rbEndOffset),
+			rbStartOffset
+		);
+		if (rightBiasedWord) {
+			return rightBiasedWord;
+		}
+
+		// (2). Else, if we were at a language boundary, check the left biased word
+		if (tokenIndex > 0 && rbStartOffset === position.column - 1) {
+			// edge case, where `position` sits between two tokens belonging to two different languages
+			const [lbStartOffset, lbEndOffset] = TextModel._findLanguageBoundaries(lineTokens, tokenIndex - 1);
+			const leftBiasedWord = getWordAtText(
+				position.column,
+				LanguageConfigurationRegistry.getWordDefinition(lineTokens.getLanguageId(tokenIndex - 1)),
+				lineContent.substring(lbStartOffset, lbEndOffset),
+				lbStartOffset
+			);
+			if (leftBiasedWord) {
+				return leftBiasedWord;
+			}
+		}
+
+		return null;
+	}
+
+	private static _findLanguageBoundaries(lineTokens: LineTokens, tokenIndex: number): [number, number] {
 		const languageId = lineTokens.getLanguageId(tokenIndex);
 
-		// First try checking right biased word
 		// go left until a different language is hit
 		let startOffset: number;
 		for (let i = tokenIndex; i >= 0 && lineTokens.getLanguageId(i) === languageId; i--) {
@@ -1759,40 +1789,7 @@ export class TextModel extends Disposable implements model.ITextModel {
 			endOffset = lineTokens.getEndOffset(i);
 		}
 
-		const rightBiasedWord = getWordAtText(
-			position.column,
-			LanguageConfigurationRegistry.getWordDefinition(languageId),
-			lineContent.substring(startOffset, endOffset),
-			startOffset
-		);
-
-		if (rightBiasedWord) {
-			return rightBiasedWord;
-		}
-
-		if (tokenIndex === 0) {
-			return null;
-		}
-
-		// Else, if we were at a language boundary, check the left biased word
-		const cursorLang = lineTokens.getLanguageId(tokenIndex);
-		const preLang = lineTokens.getLanguageId(tokenIndex - 1);
-		if (cursorLang !== preLang && tokenIndex < lineTokens.getCount()) {
-			// go left until a different language is hit
-			let startOffset: number;
-			for (let i = tokenIndex - 1; i >= 0 && lineTokens.getLanguageId(i) === preLang; i--) {
-				startOffset = lineTokens.getStartOffset(i);
-			}
-
-			return getWordAtText(
-				position.column,
-				LanguageConfigurationRegistry.getWordDefinition(languageId),
-				lineContent.substring(startOffset, lineTokens.getEndOffset(tokenIndex)),
-				startOffset
-			);
-		}
-
-		return null;
+		return [startOffset, endOffset];
 	}
 
 	public getWordUntilPosition(position: IPosition): model.IWordAtPosition {