SQL Operations Studio Public Preview 1 (0.23) release source code

src/vs/base/common/cache.ts

@@ -0,0 +1,29 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+'use strict';
+
+import { TPromise } from 'vs/base/common/winjs.base';
+
+export default class Cache<T> {
+
+	private promise: TPromise<T> = null;
+	constructor(private task: () => TPromise<T>) { }
+
+	get(): TPromise<T> {
+		if (this.promise) {
+			return this.promise;
+		}
+
+		const promise = this.task();
+
+		this.promise = new TPromise<T>((c, e) => promise.done(c, e), () => {
+			this.promise = null;
+			promise.cancel();
+		});
+
+		return this.promise;
+	}
+}