122 lines
2.5 KiB
JavaScript
122 lines
2.5 KiB
JavaScript
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'use strict';
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import CanceledError from './CanceledError.js';
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/**
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* A `CancelToken` is an object that can be used to request cancellation of an operation.
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*
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* @param {Function} executor The executor function.
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*
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* @returns {CancelToken}
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*/
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class CancelToken {
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constructor(executor) {
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if (typeof executor !== 'function') {
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throw new TypeError('executor must be a function.');
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}
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let resolvePromise;
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this.promise = new Promise(function promiseExecutor(resolve) {
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resolvePromise = resolve;
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});
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const token = this;
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// eslint-disable-next-line func-names
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this.promise.then(cancel => {
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if (!token._listeners) return;
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let i = token._listeners.length;
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while (i-- > 0) {
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token._listeners[i](cancel);
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}
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token._listeners = null;
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});
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// eslint-disable-next-line func-names
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this.promise.then = onfulfilled => {
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let _resolve;
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// eslint-disable-next-line func-names
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const promise = new Promise(resolve => {
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token.subscribe(resolve);
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_resolve = resolve;
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}).then(onfulfilled);
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promise.cancel = function reject() {
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token.unsubscribe(_resolve);
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};
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return promise;
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};
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executor(function cancel(message, config, request) {
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if (token.reason) {
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// Cancellation has already been requested
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return;
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}
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token.reason = new CanceledError(message, config, request);
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resolvePromise(token.reason);
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});
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}
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/**
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* Throws a `CanceledError` if cancellation has been requested.
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*/
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throwIfRequested() {
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if (this.reason) {
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throw this.reason;
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}
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}
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/**
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* Subscribe to the cancel signal
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*/
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subscribe(listener) {
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if (this.reason) {
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listener(this.reason);
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return;
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}
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if (this._listeners) {
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this._listeners.push(listener);
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} else {
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this._listeners = [listener];
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}
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}
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/**
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* Unsubscribe from the cancel signal
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*/
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unsubscribe(listener) {
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if (!this._listeners) {
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return;
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}
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const index = this._listeners.indexOf(listener);
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if (index !== -1) {
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this._listeners.splice(index, 1);
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}
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}
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/**
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* Returns an object that contains a new `CancelToken` and a function that, when called,
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* cancels the `CancelToken`.
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*/
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static source() {
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let cancel;
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const token = new CancelToken(function executor(c) {
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cancel = c;
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});
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return {
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token,
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cancel
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};
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}
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}
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export default CancelToken;
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