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| 'use strict';
| const {Transform} = require('stream');
|
| class ObjectTransform extends Transform {
| constructor() {
| super({
| objectMode: true
| });
| }
| }
|
| class FilterStream extends ObjectTransform {
| constructor(filter) {
| super();
| this._filter = filter;
| }
|
| _transform(data, encoding, callback) {
| if (this._filter(data)) {
| this.push(data);
| }
|
| callback();
| }
| }
|
| class UniqueStream extends ObjectTransform {
| constructor() {
| super();
| this._pushed = new Set();
| }
|
| _transform(data, encoding, callback) {
| if (!this._pushed.has(data)) {
| this.push(data);
| this._pushed.add(data);
| }
|
| callback();
| }
| }
|
| module.exports = {
| FilterStream,
| UniqueStream
| };
|
|
