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node_modules/readable-stream/lib/_stream_duplex.js

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+// 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.
+
+'use strict';
+
+/*<replacement>*/
+
+var pna = require('process-nextick-args');
+/*</replacement>*/
+
+/*<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 util = require('core-util-is');
+util.inherits = require('inherits');
+/*</replacement>*/
+
+var Readable = require('./_stream_readable');
+var Writable = require('./_stream_writable');
+
+util.inherits(Duplex, Readable);
+
+{
+  // avoid scope creep, the keys array can then be collected
+  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);
+}
+
+Object.defineProperty(Duplex.prototype, 'writableHighWaterMark', {
+  // making it explicit this property is not enumerable
+  // because otherwise some prototype manipulation in
+  // userland will fail
+  enumerable: false,
+  get: function () {
+    return this._writableState.highWaterMark;
+  }
+});
+
+// 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.
+  pna.nextTick(onEndNT, this);
+}
+
+function onEndNT(self) {
+  self.end();
+}
+
+Object.defineProperty(Duplex.prototype, 'destroyed', {
+  get: function () {
+    if (this._readableState === undefined || this._writableState === undefined) {
+      return false;
+    }
+    return this._readableState.destroyed && this._writableState.destroyed;
+  },
+  set: function (value) {
+    // we ignore the value if the stream
+    // has not been initialized yet
+    if (this._readableState === undefined || this._writableState === undefined) {
+      return;
+    }
+
+    // backward compatibility, the user is explicitly
+    // managing destroyed
+    this._readableState.destroyed = value;
+    this._writableState.destroyed = value;
+  }
+});
+
+Duplex.prototype._destroy = function (err, cb) {
+  this.push(null);
+  this.end();
+
+  pna.nextTick(cb, err);
+};