Files F98130138

CancelToken.js
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Created: Fri, Jan 10, 03:06

CancelToken.js
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	'use strict';

	import CanceledError from './CanceledError.js';

	/**
	* A `CancelToken` is an object that can be used to request cancellation of an operation.
	*
	* @param {Function} executor The executor function.
	*
	* @returns {CancelToken}
	*/
	class CancelToken {
	constructor(executor) {
	if (typeof executor !== 'function') {
	throw new TypeError('executor must be a function.');
	}

	let resolvePromise;

	this.promise = new Promise(function promiseExecutor(resolve) {
	resolvePromise = resolve;
	});

	const token = this;

	// eslint-disable-next-line func-names
	this.promise.then(cancel => {
	if (!token._listeners) return;

	let i = token._listeners.length;

	while (i-- > 0) {
	token._listeners[i](cancel);
	}
	token._listeners = null;
	});

	// eslint-disable-next-line func-names
	this.promise.then = onfulfilled => {
	let _resolve;
	// eslint-disable-next-line func-names
	const promise = new Promise(resolve => {
	token.subscribe(resolve);
	_resolve = resolve;
	}).then(onfulfilled);

	promise.cancel = function reject() {
	token.unsubscribe(_resolve);
	};

	return promise;
	};

	executor(function cancel(message, config, request) {
	if (token.reason) {
	// Cancellation has already been requested
	return;
	}

	token.reason = new CanceledError(message, config, request);
	resolvePromise(token.reason);
	});
	}

	/**
	* Throws a `CanceledError` if cancellation has been requested.
	*/
	throwIfRequested() {
	if (this.reason) {
	throw this.reason;
	}
	}

	/**
	* Subscribe to the cancel signal
	*/

	subscribe(listener) {
	if (this.reason) {
	listener(this.reason);
	return;
	}

	if (this._listeners) {
	this._listeners.push(listener);
	} else {
	this._listeners = [listener];
	}
	}

	/**
	* Unsubscribe from the cancel signal
	*/

	unsubscribe(listener) {
	if (!this._listeners) {
	return;
	}
	const index = this._listeners.indexOf(listener);
	if (index !== -1) {
	this._listeners.splice(index, 1);
	}
	}

	/**
	* Returns an object that contains a new `CancelToken` and a function that, when called,
	* cancels the `CancelToken`.
	*/
	static source() {
	let cancel;
	const token = new CancelToken(function executor(c) {
	cancel = c;
	});
	return {
	token,
	cancel
	};
	}
	}

	export default CancelToken;

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