1 | 'use strict';
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2 | var $ = require('../internals/export');
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3 | var iterate = require('../internals/iterate');
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4 | var aFunction = require('../internals/a-function');
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5 |
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6 |
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7 |
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8 | $({ target: 'Map', stat: true }, {
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9 | groupBy: function groupBy(iterable, keyDerivative) {
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10 | var newMap = new this();
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11 | aFunction(keyDerivative);
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12 | var has = aFunction(newMap.has);
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13 | var get = aFunction(newMap.get);
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14 | var set = aFunction(newMap.set);
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15 | iterate(iterable, function (element) {
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16 | var derivedKey = keyDerivative(element);
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17 | if (!has.call(newMap, derivedKey)) set.call(newMap, derivedKey, [element]);
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18 | else get.call(newMap, derivedKey).push(element);
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19 | });
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20 | return newMap;
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21 | }
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22 | });
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