Extract remote source provider registry into the vscode.git-base extension (#137656)

extensions/git-base/src/decorators.ts

@@ -0,0 +1,69 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { done } from './util';
+
+export function debounce(delay: number): Function {
+	return decorate((fn, key) => {
+		const timerKey = `$debounce$${key}`;
+
+		return function (this: any, ...args: any[]) {
+			clearTimeout(this[timerKey]);
+			this[timerKey] = setTimeout(() => fn.apply(this, args), delay);
+		};
+	});
+}
+
+export const throttle = decorate(_throttle);
+
+function _throttle<T>(fn: Function, key: string): Function {
+	const currentKey = `$throttle$current$${key}`;
+	const nextKey = `$throttle$next$${key}`;
+
+	const trigger = function (this: any, ...args: any[]) {
+		if (this[nextKey]) {
+			return this[nextKey];
+		}
+
+		if (this[currentKey]) {
+			this[nextKey] = done(this[currentKey]).then(() => {
+				this[nextKey] = undefined;
+				return trigger.apply(this, args);
+			});
+
+			return this[nextKey];
+		}
+
+		this[currentKey] = fn.apply(this, args) as Promise<T>;
+
+		const clear = () => this[currentKey] = undefined;
+		done(this[currentKey]).then(clear, clear);
+
+		return this[currentKey];
+	};
+
+	return trigger;
+}
+
+function decorate(decorator: (fn: Function, key: string) => Function): Function {
+	return (_target: any, key: string, descriptor: any) => {
+		let fnKey: string | null = null;
+		let fn: Function | null = null;
+
+		if (typeof descriptor.value === 'function') {
+			fnKey = 'value';
+			fn = descriptor.value;
+		} else if (typeof descriptor.get === 'function') {
+			fnKey = 'get';
+			fn = descriptor.get;
+		}
+
+		if (!fn || !fnKey) {
+			throw new Error('not supported');
+		}
+
+		descriptor[fnKey] = decorator(fn, key);
+	};
+}