78 lines
2.2 KiB
TypeScript
78 lines
2.2 KiB
TypeScript
/**
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* @license
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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export interface CancelablePromise<T> extends Promise<T> {
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cancel(): void;
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}
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// TODO (dmfilippov): Each function must be exported separately. According to
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// the code style guide, a namespacing is not allowed.
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export const util = {
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getCookie(name: string) {
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const key = name + '=';
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const cookies = document.cookie.split(';');
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for (let i = 0; i < cookies.length; i++) {
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let c = cookies[i];
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while (c.charAt(0) === ' ') {
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c = c.substring(1);
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}
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if (c.startsWith(key)) {
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return c.substring(key.length, c.length);
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}
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}
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return '';
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},
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/**
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* Make the promise cancelable.
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*
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* Returns a promise with a `cancel()` method wrapped around `promise`.
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* Calling `cancel()` will reject the returned promise with
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* {isCancelled: true} synchronously. If the inner promise for a cancelled
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* promise resolves or rejects this is ignored.
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*/
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makeCancelable<T>(promise: Promise<T>) {
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// True if the promise is either resolved or reject (possibly cancelled)
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let isDone = false;
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let rejectPromise: (reason?: unknown) => void;
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const wrappedPromise: CancelablePromise<T> = new Promise(
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(resolve, reject) => {
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rejectPromise = reject;
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promise.then(
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val => {
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if (!isDone) resolve(val);
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isDone = true;
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},
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error => {
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if (!isDone) reject(error);
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isDone = true;
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}
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);
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}
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) as CancelablePromise<T>;
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wrappedPromise.cancel = () => {
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if (isDone) return;
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rejectPromise({isCanceled: true});
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isDone = true;
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};
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return wrappedPromise;
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},
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};
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