text: // -*- mode: js; indent-tabs-mode: nil; js-basic-offset: 4 -*-
  //
  // Copyright 2020 The Board of Trustees of the Leland Stanford Junior University
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //    http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  //
  // Author: Giovanni Campagna <gcampagn@cs.stanford.edu>
  "use strict";
  
  const fs = require('fs');
  const byline = require('byline');
  
  const StreamUtils = require('./stream_utils');
  
  function maybeCreateReadStream(filename) {
      if (filename === '-')
          return process.stdin;
      else
          return fs.createReadStream(filename);
  }
  
  function readAllLines(files, separator = '') {
      return StreamUtils.chain(files.map((f) => maybeCreateReadStream(f).setEncoding('utf8').pipe(byline())), { objectMode: true, separator });
  }
  
  module.exports = {
      maybeCreateReadStream,
      readAllLines
  };
  