Last change
on this file since e29cc2e was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
initial commit
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File size:
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[6a3a178] | 1 | 'use strict';
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| 2 | // https://github.com/tc39/proposal-iterator-helpers
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| 3 | var $ = require('../internals/export');
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| 4 | var aFunction = require('../internals/a-function');
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| 5 | var anObject = require('../internals/an-object');
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| 6 | var getBuiltIn = require('../internals/get-built-in');
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| 7 |
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| 8 | var Promise = getBuiltIn('Promise');
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| 9 |
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| 10 | $({ target: 'AsyncIterator', proto: true, real: true }, {
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| 11 | reduce: function reduce(reducer /* , initialValue */) {
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| 12 | var iterator = anObject(this);
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| 13 | var next = aFunction(iterator.next);
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| 14 | var noInitial = arguments.length < 2;
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| 15 | var accumulator = noInitial ? undefined : arguments[1];
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| 16 | aFunction(reducer);
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| 17 |
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| 18 | return new Promise(function (resolve, reject) {
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| 19 | var loop = function () {
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| 20 | try {
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| 21 | Promise.resolve(anObject(next.call(iterator))).then(function (step) {
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| 22 | try {
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| 23 | if (anObject(step).done) {
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| 24 | noInitial ? reject(TypeError('Reduce of empty iterator with no initial value')) : resolve(accumulator);
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| 25 | } else {
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| 26 | var value = step.value;
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| 27 | if (noInitial) {
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| 28 | noInitial = false;
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| 29 | accumulator = value;
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| 30 | loop();
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| 31 | } else {
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| 32 | Promise.resolve(reducer(accumulator, value)).then(function (result) {
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| 33 | accumulator = result;
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| 34 | loop();
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| 35 | }, reject);
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| 36 | }
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| 37 | }
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| 38 | } catch (err) { reject(err); }
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| 39 | }, reject);
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| 40 | } catch (error) { reject(error); }
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| 41 | };
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| 42 |
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| 43 | loop();
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| 44 | });
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| 45 | }
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| 46 | });
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