/**
 * Copyright 2020 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */ export class TaskQueue { private _chain : Promise < void > ; constructor ( ) { this . _chain = Promise . resolve ( ) ; } postTask < T > ( task ) { const result = this . _chain . then ( task ) ; this . _chain = result . then ( ( ) => undefined , ( ) => undefined ) ; return result ; } }