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