source: imaps-frontend/node_modules/es-abstract/2015/NewPromiseCapability.js

'use strict';

var $TypeError = require('es-errors/type');

var IsCallable = require('./IsCallable');
var IsConstructor = require('./IsConstructor');

// https://262.ecma-international.org/6.0/#sec-newpromisecapability

module.exports = function NewPromiseCapability(C) {
        if (!IsConstructor(C)) {
                throw new $TypeError('C must be a constructor'); // step 1
        }

        var resolvingFunctions = { '[[Resolve]]': void undefined, '[[Reject]]': void undefined }; // step 3

        var promise = new C(function (resolve, reject) { // steps 4-5
                if (typeof resolvingFunctions['[[Resolve]]'] !== 'undefined' || typeof resolvingFunctions['[[Reject]]'] !== 'undefined') {
                        throw new $TypeError('executor has already been called'); // step 4.a, 4.b
                }
                resolvingFunctions['[[Resolve]]'] = resolve; // step 4.c
                resolvingFunctions['[[Reject]]'] = reject; // step 4.d
        }); // step 4-6

        if (!IsCallable(resolvingFunctions['[[Resolve]]']) || !IsCallable(resolvingFunctions['[[Reject]]'])) {
                throw new $TypeError('executor must provide valid resolve and reject functions'); // steps 7-8
        }

        return {
                '[[Promise]]': promise,
                '[[Resolve]]': resolvingFunctions['[[Resolve]]'],
                '[[Reject]]': resolvingFunctions['[[Reject]]']
        }; // step 9
};