// 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.

'use strict';

/*<replacement>*/

var objectKeys = Object.keys || function (obj) {

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

}; /*</replacement>*/

module.exports = Duplex;

/*<replacement>*/ var processNextTick = require('process-nextick-args'); /*</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);

var keys = objectKeys(Writable.prototype); for (var v = 0; v < keys.length; v++) {

var method = keys[v];
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.
processNextTick(onEndNT, this);

}

function onEndNT(self) {

self.end();

}

function forEach(xs, f) {

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

}