// Copyright Joyent, Inc. and other Node contributors. // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the // “Software”), to deal in the Software without restriction, including // without limitation the rights to use, copy, modify, merge, publish, // distribute, sublicense, and/or sell copies of the Software, and to permit // persons to whom the Software is furnished to do so, subject to the // following conditions: // // The above copyright notice and this permission notice shall be included // in all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN // NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, // DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE // USE OR OTHER DEALINGS IN THE SOFTWARE.

// a duplex stream is just a stream that is both readable and writable. // Since JS doesn’t have multiple prototypal inheritance, this class // prototypally inherits from Readable, and then parasitically from // Writable.

module.exports = Duplex;

/*<replacement>*/ var objectKeys = Object.keys || function (obj) {

var keys = [];
for (var key in obj) keys.push(key);
return keys;

} /*</replacement>*/

/*<replacement>*/ var util = require(‘core-util-is’); util.inherits = require(‘inherits’); /*</replacement>*/

var Readable = require(‘./_stream_readable’); var Writable = require(‘./_stream_writable’);

util.inherits(Duplex, Readable);

forEach(objectKeys(Writable.prototype), function(method) {

if (!Duplex.prototype[method])
  Duplex.prototype[method] = Writable.prototype[method];

});

function Duplex(options) {

if (!(this instanceof Duplex))
  return new Duplex(options);

Readable.call(this, options);
Writable.call(this, options);

if (options && options.readable === false)
  this.readable = false;

if (options && options.writable === false)
  this.writable = false;

this.allowHalfOpen = true;
if (options && options.allowHalfOpen === false)
  this.allowHalfOpen = false;

this.once('end', onend);

}

// the no-half-open enforcer function onend() {

// if we allow half-open state, or if the writable side ended,
// then we're ok.
if (this.allowHalfOpen || this._writableState.ended)
  return;

// no more data can be written.
// But allow more writes to happen in this tick.
process.nextTick(this.end.bind(this));

}

function forEach (xs, f) {

for (var i = 0, l = xs.length; i < l; i++) {
  f(xs[i], i);
}

}