source: imaps-frontend/node_modules/es-abstract/2019/FlattenIntoArray.js

'use strict';

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

var MAX_SAFE_INTEGER = require('../helpers/maxSafeInteger');

var Call = require('./Call');
var CreateDataPropertyOrThrow = require('./CreateDataPropertyOrThrow');
var Get = require('./Get');
var HasProperty = require('./HasProperty');
var IsArray = require('./IsArray');
var ToLength = require('./ToLength');
var ToString = require('./ToString');

// https://262.ecma-international.org/10.0/#sec-flattenintoarray

module.exports = function FlattenIntoArray(target, source, sourceLen, start, depth) {
        var mapperFunction;
        if (arguments.length > 5) {
                mapperFunction = arguments[5];
        }

        var targetIndex = start;
        var sourceIndex = 0;
        while (sourceIndex < sourceLen) {
                var P = ToString(sourceIndex);
                var exists = HasProperty(source, P);
                if (exists === true) {
                        var element = Get(source, P);
                        if (typeof mapperFunction !== 'undefined') {
                                if (arguments.length <= 6) {
                                        throw new $TypeError('Assertion failed: thisArg is required when mapperFunction is provided');
                                }
                                element = Call(mapperFunction, arguments[6], [element, sourceIndex, source]);
                        }
                        var shouldFlatten = false;
                        if (depth > 0) {
                                shouldFlatten = IsArray(element);
                        }
                        if (shouldFlatten) {
                                var elementLen = ToLength(Get(element, 'length'));
                                targetIndex = FlattenIntoArray(target, element, elementLen, targetIndex, depth - 1);
                        } else {
                                if (targetIndex >= MAX_SAFE_INTEGER) {
                                        throw new $TypeError('index too large');
                                }
                                CreateDataPropertyOrThrow(target, ToString(targetIndex), element);
                                targetIndex += 1;
                        }
                }
                sourceIndex += 1;
        }

        return targetIndex;
};