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