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28 lines
1.0 KiB
28 lines
1.0 KiB
'use strict'; |
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var $ = require('../internals/export'); |
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var call = require('../internals/function-call'); |
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var uncurryThis = require('../internals/function-uncurry-this'); |
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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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var push = uncurryThis([].push); |
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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, forced: 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 (!call(has, newMap, derivedKey)) call(set, newMap, derivedKey, [element]); |
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else push(call(get, newMap, derivedKey), 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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