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26 lines
818 B
26 lines
818 B
'use strict'; |
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// https://tc39.github.io/proposal-setmap-offrom/ |
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var aFunction = require('../internals/a-function'); |
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var bind = require('../internals/function-bind-context'); |
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var iterate = require('../internals/iterate'); |
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|
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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, A, n, boundFunction; |
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aFunction(this); |
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mapping = mapFn !== undefined; |
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if (mapping) aFunction(mapFn); |
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if (source == undefined) return new this(); |
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A = []; |
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if (mapping) { |
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n = 0; |
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boundFunction = bind(mapFn, length > 2 ? arguments[2] : undefined, 2); |
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iterate(source, function (nextItem) { |
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A.push(boundFunction(nextItem, n++)); |
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}); |
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} else { |
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iterate(source, A.push, A); |
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} |
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return new this(A); |
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};
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