Emit a tokens change event only if there are changed tokens

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

@@ -1713,7 +1713,7 @@ export class TextModel extends Disposable implements model.ITextModel {
 			throw new Error('Illegal value for lineNumber');
 		}
 
-		this._tokens.setTokens(this._languageIdentifier.id, lineNumber - 1, this._buffer.getLineLength(lineNumber), tokens);
+		this._tokens.setTokens(this._languageIdentifier.id, lineNumber - 1, this._buffer.getLineLength(lineNumber), tokens, false);
 	}
 
 	public setTokens(tokens: MultilineTokens[]): void {
@@ -1725,16 +1725,34 @@ export class TextModel extends Disposable implements model.ITextModel {
 
 		for (let i = 0, len = tokens.length; i < len; i++) {
 			const element = tokens[i];
-			ranges.push({ fromLineNumber: element.startLineNumber, toLineNumber: element.startLineNumber + element.tokens.length - 1 });
+			let minChangedLineNumber = 0;
+			let maxChangedLineNumber = 0;
+			let hasChange = false;
 			for (let j = 0, lenJ = element.tokens.length; j < lenJ; j++) {
-				this.setLineTokens(element.startLineNumber + j, element.tokens[j]);
+				const lineNumber = element.startLineNumber + j;
+				if (hasChange) {
+					this._tokens.setTokens(this._languageIdentifier.id, lineNumber - 1, this._buffer.getLineLength(lineNumber), element.tokens[j], false);
+					maxChangedLineNumber = lineNumber;
+				} else {
+					const lineHasChange = this._tokens.setTokens(this._languageIdentifier.id, lineNumber - 1, this._buffer.getLineLength(lineNumber), element.tokens[j], true);
+					if (lineHasChange) {
+						hasChange = true;
+						minChangedLineNumber = lineNumber;
+						maxChangedLineNumber = lineNumber;
+					}
+				}
+			}
+			if (hasChange) {
+				ranges.push({ fromLineNumber: minChangedLineNumber, toLineNumber: maxChangedLineNumber });
 			}
 		}
 
-		this._emitModelTokensChangedEvent({
-			tokenizationSupportChanged: false,
-			ranges: ranges
-		});
+		if (ranges.length > 0) {
+			this._emitModelTokensChangedEvent({
+				tokenizationSupportChanged: false,
+				ranges: ranges
+			});
+		}
 	}
 
 	public setSemanticTokens(tokens: MultilineTokens2[] | null): void {

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

@@ -964,10 +964,35 @@ export class TokensStore {
 		this._len += insertCount;
 	}
 
-	public setTokens(topLevelLanguageId: LanguageId, lineIndex: number, lineTextLength: number, _tokens: Uint32Array | ArrayBuffer | null): void {
+	public setTokens(topLevelLanguageId: LanguageId, lineIndex: number, lineTextLength: number, _tokens: Uint32Array | ArrayBuffer | null, checkEquality: boolean): boolean {
 		const tokens = TokensStore._massageTokens(topLevelLanguageId, lineTextLength, _tokens);
 		this._ensureLine(lineIndex);
+		const oldTokens = this._lineTokens[lineIndex];
 		this._lineTokens[lineIndex] = tokens;
+
+		if (checkEquality) {
+			return !TokensStore._equals(oldTokens, tokens);
+		}
+		return false;
+	}
+
+	private static _equals(_a: Uint32Array | ArrayBuffer | null, _b: Uint32Array | ArrayBuffer | null) {
+		if (!_a || !_b) {
+			return !_a && !_b;
+		}
+
+		const a = toUint32Array(_a);
+		const b = toUint32Array(_b);
+
+		if (a.length !== b.length) {
+			return false;
+		}
+		for (let i = 0, len = a.length; i < len; i++) {
+			if (a[i] !== b[i]) {
+				return false;
+			}
+		}
+		return true;
 	}
 
 	//#region Editing