'use strict';
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var Cancel = require('./Cancel');
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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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* @class
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* @param {Function} executor The executor function.
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*/
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function CancelToken(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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var 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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var token = this;
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executor(function cancel(message) {
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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 Cancel(message);
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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 `Cancel` if cancellation has been requested.
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*/
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CancelToken.prototype.throwIfRequested = function 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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* 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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CancelToken.source = function source() {
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var cancel;
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var 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: token,
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cancel: cancel
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};
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};
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module.exports = CancelToken;
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