Last change
on this file since 6a80231 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:
677 bytes
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[6a3a178] | 1 | 'use strict';
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| 2 | const {Transform} = require('stream');
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| 3 |
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| 4 | class ObjectTransform extends Transform {
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| 5 | constructor() {
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| 6 | super({
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| 7 | objectMode: true
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| 8 | });
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| 9 | }
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| 10 | }
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| 11 |
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| 12 | class FilterStream extends ObjectTransform {
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| 13 | constructor(filter) {
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| 14 | super();
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| 15 | this._filter = filter;
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| 16 | }
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| 17 |
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| 18 | _transform(data, encoding, callback) {
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| 19 | if (this._filter(data)) {
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| 20 | this.push(data);
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| 21 | }
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| 22 |
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| 23 | callback();
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| 24 | }
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| 25 | }
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| 26 |
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| 27 | class UniqueStream extends ObjectTransform {
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| 28 | constructor() {
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| 29 | super();
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| 30 | this._pushed = new Set();
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| 31 | }
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| 32 |
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| 33 | _transform(data, encoding, callback) {
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| 34 | if (!this._pushed.has(data)) {
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| 35 | this.push(data);
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| 36 | this._pushed.add(data);
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| 37 | }
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| 38 |
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| 39 | callback();
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| 40 | }
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| 41 | }
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| 42 |
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| 43 | module.exports = {
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| 44 | FilterStream,
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| 45 | UniqueStream
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| 46 | };
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