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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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