Last change
on this file since eed0bf8 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
initial commit
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Property mode
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100644
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File size:
1.6 KB
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[6a3a178] | 1 | 'use strict';
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| 2 | const AggregateError = require('aggregate-error');
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| 3 |
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| 4 | module.exports = async (
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| 5 | iterable,
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| 6 | mapper,
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| 7 | {
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| 8 | concurrency = Infinity,
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| 9 | stopOnError = true
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| 10 | } = {}
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| 11 | ) => {
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| 12 | return new Promise((resolve, reject) => {
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| 13 | if (typeof mapper !== 'function') {
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| 14 | throw new TypeError('Mapper function is required');
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| 15 | }
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| 16 |
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| 17 | if (!((Number.isSafeInteger(concurrency) || concurrency === Infinity) && concurrency >= 1)) {
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| 18 | throw new TypeError(`Expected \`concurrency\` to be an integer from 1 and up or \`Infinity\`, got \`${concurrency}\` (${typeof concurrency})`);
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| 19 | }
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| 20 |
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| 21 | const result = [];
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| 22 | const errors = [];
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| 23 | const iterator = iterable[Symbol.iterator]();
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| 24 | let isRejected = false;
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| 25 | let isIterableDone = false;
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| 26 | let resolvingCount = 0;
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| 27 | let currentIndex = 0;
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| 28 |
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| 29 | const next = () => {
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| 30 | if (isRejected) {
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| 31 | return;
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| 32 | }
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| 33 |
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| 34 | const nextItem = iterator.next();
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| 35 | const index = currentIndex;
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| 36 | currentIndex++;
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| 37 |
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| 38 | if (nextItem.done) {
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| 39 | isIterableDone = true;
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| 40 |
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| 41 | if (resolvingCount === 0) {
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| 42 | if (!stopOnError && errors.length !== 0) {
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| 43 | reject(new AggregateError(errors));
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| 44 | } else {
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| 45 | resolve(result);
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| 46 | }
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| 47 | }
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| 48 |
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| 49 | return;
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| 50 | }
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| 51 |
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| 52 | resolvingCount++;
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| 53 |
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| 54 | (async () => {
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| 55 | try {
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| 56 | const element = await nextItem.value;
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| 57 | result[index] = await mapper(element, index);
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| 58 | resolvingCount--;
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| 59 | next();
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| 60 | } catch (error) {
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| 61 | if (stopOnError) {
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| 62 | isRejected = true;
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| 63 | reject(error);
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| 64 | } else {
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| 65 | errors.push(error);
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| 66 | resolvingCount--;
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| 67 | next();
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| 68 | }
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| 69 | }
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| 70 | })();
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| 71 | };
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| 72 |
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| 73 | for (let i = 0; i < concurrency; i++) {
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| 74 | next();
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| 75 |
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| 76 | if (isIterableDone) {
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| 77 | break;
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| 78 | }
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| 79 | }
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| 80 | });
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| 81 | };
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