89 lines
1.6 KiB
JavaScript
89 lines
1.6 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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get isCanceled() {
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return true;
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}
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}
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class PCancelable {
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static fn(userFn) {
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return function () {
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const args = [].slice.apply(arguments);
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return new PCancelable((resolve, reject, onCancel) => {
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args.push(onCancel);
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userFn.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._cancelHandlers = [];
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this._isPending = true;
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this._isCanceled = 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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value => {
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this._isPending = false;
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resolve(value);
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},
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error => {
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this._isPending = false;
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reject(error);
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},
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handler => {
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this._cancelHandlers.push(handler);
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}
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);
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});
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}
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then(onFulfilled, onRejected) {
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return this._promise.then(onFulfilled, onRejected);
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}
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catch(onRejected) {
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return this._promise.catch(onRejected);
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}
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finally(onFinally) {
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return this._promise.finally(onFinally);
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}
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cancel() {
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if (!this._isPending || this._isCanceled) {
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return;
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}
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if (this._cancelHandlers.length > 0) {
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try {
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for (const handler of this._cancelHandlers) {
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handler();
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}
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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._isCanceled = true;
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this._reject(new CancelError());
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}
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get isCanceled() {
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return this._isCanceled;
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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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