| 'use strict'; |
| // https://github.com/tc39/proposal-iterator-helpers |
| var $ = require('../internals/export'); |
| var iterate = require('../internals/iterate'); |
| var aFunction = require('../internals/a-function'); |
| var anObject = require('../internals/an-object'); |
| |
| $({ target: 'Iterator', proto: true, real: true }, { |
| reduce: function reduce(reducer /* , initialValue */) { |
| anObject(this); |
| aFunction(reducer); |
| var noInitial = arguments.length < 2; |
| var accumulator = noInitial ? undefined : arguments[1]; |
| iterate(this, function (value) { |
| if (noInitial) { |
| noInitial = false; |
| accumulator = value; |
| } else { |
| accumulator = reducer(accumulator, value); |
| } |
| }, undefined, false, true); |
| if (noInitial) throw TypeError('Reduce of empty iterator with no initial value'); |
| return accumulator; |
| } |
| }); |