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- 'use strict';
-
- class CancelError extends Error {
- constructor() {
- super('Promise was canceled');
- this.name = 'CancelError';
- }
- }
-
- class PCancelable {
- static fn(fn) {
- return function () {
- const args = [].slice.apply(arguments);
- return new PCancelable((onCancel, resolve, reject) => {
- args.unshift(onCancel);
- fn.apply(null, args).then(resolve, reject);
- });
- };
- }
-
- constructor(executor) {
- this._pending = true;
- this._canceled = false;
-
- this._promise = new Promise((resolve, reject) => {
- this._reject = reject;
-
- return executor(
- fn => {
- this._cancel = fn;
- },
- val => {
- this._pending = false;
- resolve(val);
- },
- err => {
- this._pending = false;
- reject(err);
- }
- );
- });
- }
-
- then() {
- return this._promise.then.apply(this._promise, arguments);
- }
-
- catch() {
- return this._promise.catch.apply(this._promise, arguments);
- }
-
- cancel() {
- if (!this._pending || this._canceled) {
- return;
- }
-
- if (typeof this._cancel === 'function') {
- try {
- this._cancel();
- } catch (err) {
- this._reject(err);
- }
- }
-
- this._canceled = true;
- this._reject(new CancelError());
- }
-
- get canceled() {
- return this._canceled;
- }
- }
-
- Object.setPrototypeOf(PCancelable.prototype, Promise.prototype);
-
- module.exports = PCancelable;
- module.exports.CancelError = CancelError;
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