old_contents: // Copyright (c) 2015 Uber Technologies, Inc.
  //
  // 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.
  
  'use strict';
  
  var assert = require('assert');
  
  // Peer and Circuit are state machines.
  
  module.exports = StateMachine;
  
  function StateMachine() {
      var self = this;
      self.state = null;
      self.stateOptions = null;
  }
  
  StateMachine.prototype.setState = function setState(StateType) {
      var self = this;
  
      var currentType = self.state && self.state.type;
      if (currentType &&
          StateType.prototype.type &&
          StateType.prototype.type === currentType) {
          return;
      }
  
      assert(self.stateOptions, 'state machine must have stateOptions');
      var state = new StateType(self.stateOptions);
      if (state && state.type === currentType) {
          return;
      }
  
      var oldState = self.state;
      self.state = state;
      self.stateChangedEvent.emit(self, [oldState, state]);
  };
  
new_contents: // Copyright (c) 2015 Uber Technologies, Inc.
  //
  // 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.
  
  'use strict';
  
  var assert = require('assert');
  
  // Peer and Circuit are state machines.
  
  module.exports = StateMachine;
  
  function StateMachine() {
      var self = this;
      self.state = null;
      self.stateOptions = null;
  }
  
  StateMachine.prototype.setState = function setState(StateType) {
      var self = this;
  
      var currentType = self.state && self.state.type;
      if (currentType &&
          StateType.prototype.type &&
          StateType.prototype.type === currentType) {
          return null;
      }
  
      assert(self.stateOptions, 'state machine must have stateOptions');
      var state = new StateType(self.stateOptions);
      if (state && state.type === currentType) {
          return null;
      }
  
      var oldState = self.state;
      self.state = state;
      self.stateChangedEvent.emit(self, [oldState, state]);
      return state;
  };
  
subject: return new state from #setState