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