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notes/node_modules/readable-stream/lib/_stream_duplex.js

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2017-03-09 13:16:08 -05:00
// 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);
}
}