| 'use strict'; |
| // https://github.com/tc39/proposal-iterator-helpers |
| var $ = require('../internals/export'); |
| var aFunction = require('../internals/a-function'); |
| var anObject = require('../internals/an-object'); |
| var getBuiltIn = require('../internals/get-built-in'); |
| |
| var Promise = getBuiltIn('Promise'); |
| |
| $({ target: 'AsyncIterator', proto: true, real: true }, { |
| reduce: function reduce(reducer /* , initialValue */) { |
| var iterator = anObject(this); |
| var next = aFunction(iterator.next); |
| var noInitial = arguments.length < 2; |
| var accumulator = noInitial ? undefined : arguments[1]; |
| aFunction(reducer); |
| |
| return new Promise(function (resolve, reject) { |
| var loop = function () { |
| try { |
| Promise.resolve(anObject(next.call(iterator))).then(function (step) { |
| try { |
| if (anObject(step).done) { |
| noInitial ? reject(TypeError('Reduce of empty iterator with no initial value')) : resolve(accumulator); |
| } else { |
| var value = step.value; |
| if (noInitial) { |
| noInitial = false; |
| accumulator = value; |
| loop(); |
| } else { |
| Promise.resolve(reducer(accumulator, value)).then(function (result) { |
| accumulator = result; |
| loop(); |
| }, reject); |
| } |
| } |
| } catch (err) { reject(err); } |
| }, reject); |
| } catch (error) { reject(error); } |
| }; |
| |
| loop(); |
| }); |
| } |
| }); |