concat-reader.js

module.exports = Concat;

var util = require('util');
var Readable = require('readable-stream');
var assert = require('assert');

// mostly for instanceof checks or whatever.
// but also for .pipe() etc
util.inherits(Concat, Readable)

function Concat(/* readable, readable... */) {
  // no relevant options, since we override read() anyway.
  Readable.call(this);

  this._length = arguments.length;
  this._sources = new Array(this._length);
  for (var i = 0; i < this._length; i++) {
    var source = this._sources[i] = arguments[i];
    // only new readables are supported.
    assert(source instanceof Readable);
    source.on('end', this._next.bind(this));
    source.on('error', this.emit.bind(this, 'error'));
  }

  this._index = 0;
}

Concat.prototype.read = function(n) {
  return this._sources[this._index].read(n);
};

Concat.prototype._next = function() {
  this._index++;
  if (this._index === this._length{
    return this.emit('end');
};