source: frontend/node_modules/es-abstract/2020/GetIterator.js

'use strict';

var GetIntrinsic = require('get-intrinsic');

var $TypeError = require('es-errors/type');
var $SyntaxError = require('es-errors/syntax');
var isObject = require('es-object-atoms/isObject');
var $asyncIterator = GetIntrinsic('%Symbol.asyncIterator%', true);

var inspect = require('object-inspect');
var hasSymbols = require('has-symbols')();

var getIteratorMethod = require('../helpers/getIteratorMethod');
var AdvanceStringIndex = require('./AdvanceStringIndex');
var Call = require('./Call');
var GetMethod = require('./GetMethod');

var ES = {
        AdvanceStringIndex: AdvanceStringIndex,
        GetMethod: GetMethod
};

// https://262.ecma-international.org/9.0/#sec-getiterator

module.exports = function GetIterator(obj, hint, method) {
        var actualHint = hint;
        if (arguments.length < 2) {
                actualHint = 'sync';
        }
        if (actualHint !== 'sync' && actualHint !== 'async') {
                throw new $TypeError("Assertion failed: `hint` must be one of 'sync' or 'async', got " + inspect(hint));
        }

        var actualMethod = method;
        if (arguments.length < 3) {
                if (actualHint === 'async') {
                        if (hasSymbols && $asyncIterator) {
                                actualMethod = GetMethod(obj, $asyncIterator);
                        }
                        if (typeof actualMethod === 'undefined') {
                                throw new $SyntaxError("async from sync iterators aren't currently supported");
                        }
                } else {
                        actualMethod = getIteratorMethod(ES, obj);
                }
        }
        var iterator = Call(actualMethod, obj);
        if (!isObject(iterator)) {
                throw new $TypeError('iterator must return an object');
        }

        return iterator;

        // TODO: This should return an IteratorRecord
        /*
        var nextMethod = GetV(iterator, 'next');
        return {
                '[[Iterator]]': iterator,
                '[[NextMethod]]': nextMethod,
                '[[Done]]': false
        };
        */
};