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32 lines
1.1 KiB
32 lines
1.1 KiB
'use strict';
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var $ = require('../internals/export');
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var iterate = require('../internals/iterate');
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var aCallable = require('../internals/a-callable');
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var anObject = require('../internals/an-object');
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var getIteratorDirect = require('../internals/get-iterator-direct');
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var $TypeError = TypeError;
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// `Iterator.prototype.reduce` method
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// https://github.com/tc39/proposal-iterator-helpers
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$({ target: 'Iterator', proto: true, real: true }, {
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reduce: function reduce(reducer /* , initialValue */) {
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anObject(this);
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aCallable(reducer);
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var record = getIteratorDirect(this);
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var noInitial = arguments.length < 2;
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var accumulator = noInitial ? undefined : arguments[1];
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var counter = 0;
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iterate(record, function (value) {
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if (noInitial) {
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noInitial = false;
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accumulator = value;
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} else {
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accumulator = reducer(accumulator, value, counter);
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}
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counter++;
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}, { IS_RECORD: true });
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if (noInitial) throw new $TypeError('Reduce of empty iterator with no initial value');
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return accumulator;
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}
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});
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