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34 lines
1.2 KiB
34 lines
1.2 KiB
'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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