| 1 | 'use strict';
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| 2 |
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| 3 | var aFunction = require('../internals/a-function');
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| 4 | var bind = require('../internals/bind-context');
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| 5 | var iterate = require('../internals/iterate');
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| 6 |
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| 7 | module.exports = function from(source /* , mapFn, thisArg */) {
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| 8 | var length = arguments.length;
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| 9 | var mapFn = length > 1 ? arguments[1] : undefined;
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| 10 | var mapping, A, n, boundFunction;
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| 11 | aFunction(this);
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| 12 | mapping = mapFn !== undefined;
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| 13 | if (mapping) aFunction(mapFn);
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| 14 | if (source == undefined) return new this();
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| 15 | A = [];
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| 16 | if (mapping) {
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| 17 | n = 0;
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| 18 | boundFunction = bind(mapFn, length > 2 ? arguments[2] : undefined, 2);
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| 19 | iterate(source, function (nextItem) {
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| 20 | A.push(boundFunction(nextItem, n++));
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| 21 | });
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| 22 | } else {
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| 23 | iterate(source, A.push, A);
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| 24 | }
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| 25 | return new this(A);
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| 26 | };
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