Clear characterSet instead of recreating it on every parameter hints update (microsoft#164195)

Author: mjbvz

src/vs/editor/common/core/characterClassifier.ts

@@ -12,14 +12,14 @@ export class CharacterClassifier<T extends number> {
 	/**
 	 * Maintain a compact (fully initialized ASCII map for quickly classifying ASCII characters - used more often in code).
 	 */
-	protected _asciiMap: Uint8Array;
+	protected readonly _asciiMap: Uint8Array;
 
 	/**
 	 * The entire map (sparse array).
 	 */
-	protected _map: Map<number, number>;
+	protected readonly _map: Map<number, number>;
 
-	protected _defaultValue: number;
+	protected readonly _defaultValue: number;
 
 	constructor(_defaultValue: T) {
 		const defaultValue = toUint8(_defaultValue);
@@ -30,10 +30,8 @@ export class CharacterClassifier<T extends number> {
 	}
 
 	private static _createAsciiMap(defaultValue: number): Uint8Array {
-		const asciiMap: Uint8Array = new Uint8Array(256);
-		for (let i = 0; i < 256; i++) {
-			asciiMap[i] = defaultValue;
-		}
+		const asciiMap = new Uint8Array(256);
+		asciiMap.fill(defaultValue);
 		return asciiMap;
 	}
 
@@ -54,6 +52,11 @@ export class CharacterClassifier<T extends number> {
 			return <T>(this._map.get(charCode) || this._defaultValue);
 		}
 	}
+
+	public clear() {
+		this._asciiMap.fill(this._defaultValue);
+		this._map.clear();
+	}
 }
 
 const enum Boolean {
@@ -76,4 +79,8 @@ export class CharacterSet {
 	public has(charCode: number): boolean {
 		return (this._actual.get(charCode) === Boolean.True);
 	}
+
+	public clear(): void {
+		return this._actual.clear();
+	}
 }

src/vs/editor/contrib/parameterHints/browser/parameterHintsModel.ts

@@ -56,12 +56,14 @@ export class ParameterHintsModel extends Disposable {
 
 	private readonly editor: ICodeEditor;
 	private readonly providers: LanguageFeatureRegistry<languages.SignatureHelpProvider>;
+
 	private triggerOnType = false;
 	private _state: ParameterHintState.State = ParameterHintState.Default;
 	private _pendingTriggers: TriggerContext[] = [];
+
 	private readonly _lastSignatureHelpResult = this._register(new MutableDisposable<languages.SignatureHelpResult>());
-	private triggerChars = new CharacterSet();
-	private retriggerChars = new CharacterSet();
+	private readonly triggerChars = new CharacterSet();
+	private readonly retriggerChars = new CharacterSet();
 
 	private readonly throttledDelayer: Delayer<boolean>;
 	private triggerId = 0;
@@ -248,9 +250,8 @@ export class ParameterHintsModel extends Disposable {
 	private onModelChanged(): void {
 		this.cancel();
 
-		// Update trigger characters
-		this.triggerChars = new CharacterSet();
-		this.retriggerChars = new CharacterSet();
+		this.triggerChars.clear();
+		this.retriggerChars.clear();
 
 		const model = this.editor.getModel();
 		if (!model) {
@@ -259,14 +260,19 @@ export class ParameterHintsModel extends Disposable {
 
 		for (const support of this.providers.ordered(model)) {
 			for (const ch of support.signatureHelpTriggerCharacters || []) {
-				this.triggerChars.add(ch.charCodeAt(0));
+				if (ch.length) {
+					const charCode = ch.charCodeAt(0);
+					this.triggerChars.add(charCode);
 
-				// All trigger characters are also considered retrigger characters
-				this.retriggerChars.add(ch.charCodeAt(0));
+					// All trigger characters are also considered retrigger characters
+					this.retriggerChars.add(charCode);
+				}
 			}
 
 			for (const ch of support.signatureHelpRetriggerCharacters || []) {
-				this.retriggerChars.add(ch.charCodeAt(0));
+				if (ch.length) {
+					this.retriggerChars.add(ch.charCodeAt(0));
+				}
 			}
 		}
 	}