core-worker/src/DuplexStream.js

CoreWorker

/*
 * This file is part of CoreWorker.
 *
 * CoreWorker is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * CoreWorker is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with CoreWorker.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright 2016 TeeAge-Beatz UG (haftungsbeschränkt)
 */

import { Transform } from "stream";

export default class DuplexStream extends Transform {
    constructor(instance) {
        super();

        this.instance = instance;

        this.instance.startStream();
        this.instance.emitter.on("data", ::this.push);
    }

    /**
     * Pipes data into process's stdin
     *
     * @param {Buffer}   chunk    forwarded to stdin
     * @param {String}   encoding of current chunk
     * @param {Function} next     to finalize a chunk
     */
    _transform(chunk, encoding, next) {
        this.instance.write(chunk);

        next();
    }

    /**
     * process.stdin ends with the readable stream
     * to process the piped data
     */
    end() {
        this.instance.end();
    }
}