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28 lines
947 B
28 lines
947 B
'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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