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1// Copyright (C) 2018 The Android Open Source Project
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// tslint:disable:no-any
16
17/**
18 * Promise wrapper with exposed resolve and reject callbacks.
19 */
20export interface Deferred<T> extends Promise<T> {
21  readonly resolve: (value?: T|PromiseLike<T>) => void;
22  readonly reject: (reason?: any) => void;
23}
24
25/**
26 * Create a promise with exposed resolve and reject callbacks.
27 */
28export function defer<T>(): Deferred<T> {
29  let resolve = null as any;
30  let reject = null as any;
31  const p = new Promise((res, rej) => [resolve, reject] = [res, rej]);
32  return Object.assign(p, {resolve, reject}) as any;
33}
34