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25 lines
876 B
25 lines
876 B
'use strict';
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var $ = require('../internals/export');
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var aCallable = require('../internals/a-callable');
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var getIterator = require('../internals/get-iterator');
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var iterate = require('../internals/iterate');
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// `Map.groupBy` method
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// https://github.com/tc39/proposal-collection-methods
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$({ target: 'Map', stat: true }, {
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groupBy: function groupBy(iterable, keyDerivative) {
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aCallable(keyDerivative);
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var iterator = getIterator(iterable);
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var newMap = new this();
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var has = aCallable(newMap.has);
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var get = aCallable(newMap.get);
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var set = aCallable(newMap.set);
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iterate(iterator, function (element) {
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var derivedKey = keyDerivative(element);
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if (!has.call(newMap, derivedKey)) set.call(newMap, derivedKey, [element]);
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else get.call(newMap, derivedKey).push(element);
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}, { IS_ITERATOR: true });
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return newMap;
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}
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});
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