35 lines
1.2 KiB
JavaScript
35 lines
1.2 KiB
JavaScript
'use strict';
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var $TypeError = require('es-errors/type');
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var IsCallable = require('./IsCallable');
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var IsConstructor = require('./IsConstructor');
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// https://262.ecma-international.org/6.0/#sec-newpromisecapability
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module.exports = function NewPromiseCapability(C) {
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if (!IsConstructor(C)) {
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throw new $TypeError('C must be a constructor'); // step 1
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}
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var resolvingFunctions = { '[[Resolve]]': void undefined, '[[Reject]]': void undefined }; // step 3
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var promise = new C(function (resolve, reject) { // steps 4-5
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if (typeof resolvingFunctions['[[Resolve]]'] !== 'undefined' || typeof resolvingFunctions['[[Reject]]'] !== 'undefined') {
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throw new $TypeError('executor has already been called'); // step 4.a, 4.b
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}
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resolvingFunctions['[[Resolve]]'] = resolve; // step 4.c
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resolvingFunctions['[[Reject]]'] = reject; // step 4.d
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}); // step 4-6
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if (!IsCallable(resolvingFunctions['[[Resolve]]']) || !IsCallable(resolvingFunctions['[[Reject]]'])) {
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throw new $TypeError('executor must provide valid resolve and reject functions'); // steps 7-8
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}
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return {
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'[[Promise]]': promise,
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'[[Resolve]]': resolvingFunctions['[[Resolve]]'],
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'[[Reject]]': resolvingFunctions['[[Reject]]']
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}; // step 9
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};
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