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'use strict';
// https://tc39.github.io/proposal-flatMap/#sec-FlattenIntoArray
var isArray = require('./_is-array');
var isObject = require('./_is-object');
var toLength = require('./_to-length');
var ctx = require('./_ctx');
var IS_CONCAT_SPREADABLE = require('./_wks')('isConcatSpreadable');
function flattenIntoArray(target, original, source, sourceLen, start, depth, mapper, thisArg) {
var targetIndex = start;
var sourceIndex = 0;
var mapFn = mapper ? ctx(mapper, thisArg, 3) : false;
var element, spreadable;
while (sourceIndex < sourceLen) {
if (sourceIndex in source) {
element = mapFn ? mapFn(source[sourceIndex], sourceIndex, original) : source[sourceIndex];
spreadable = false;
if (isObject(element)) {
spreadable = element[IS_CONCAT_SPREADABLE];
spreadable = spreadable !== undefined ? !!spreadable : isArray(element);
}
if (spreadable && depth > 0) {
targetIndex = flattenIntoArray(target, original, element, toLength(element.length), targetIndex, depth - 1) - 1;
} else {
if (targetIndex >= 0x1fffffffffffff) throw TypeError();
target[targetIndex] = element;
}
targetIndex++;
}
sourceIndex++;
}
return targetIndex;
}
module.exports = flattenIntoArray;
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