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29 lines
947 B
29 lines
947 B
3 years ago
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'use strict';
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// https://github.com/tc39/proposal-iterator-helpers
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var $ = require('../internals/export');
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var global = require('../internals/global');
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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 TypeError = global.TypeError;
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$({ target: 'Iterator', proto: true, real: true, forced: 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 noInitial = arguments.length < 2;
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var accumulator = noInitial ? undefined : arguments[1];
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iterate(this, 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);
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}
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}, { IS_ITERATOR: true });
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if (noInitial) throw 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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