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39 lines
1.3 KiB
39 lines
1.3 KiB
'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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