27 lines
818 B
JavaScript
27 lines
818 B
JavaScript
'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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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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