'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
};