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30 lines
982 B
30 lines
982 B
'use strict'; |
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// https://tc39.github.io/proposal-setmap-offrom/ |
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var bind = require('../internals/function-bind-context'); |
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var call = require('../internals/function-call'); |
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var aCallable = require('../internals/a-callable'); |
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var aConstructor = require('../internals/a-constructor'); |
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var iterate = require('../internals/iterate'); |
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var push = [].push; |
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module.exports = function from(source /* , mapFn, thisArg */) { |
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var length = arguments.length; |
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var mapFn = length > 1 ? arguments[1] : undefined; |
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var mapping, array, n, boundFunction; |
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aConstructor(this); |
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mapping = mapFn !== undefined; |
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if (mapping) aCallable(mapFn); |
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if (source == undefined) return new this(); |
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array = []; |
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if (mapping) { |
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n = 0; |
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boundFunction = bind(mapFn, length > 2 ? arguments[2] : undefined); |
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iterate(source, function (nextItem) { |
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call(push, array, boundFunction(nextItem, n++)); |
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}); |
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} else { |
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iterate(source, push, { that: array }); |
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} |
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return new this(array); |
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};
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