/*
 * Copyright 2011 Steven Gribble
 *
 *  This file is part of the UW CSE 333 course project sequence
 *  (333proj).
 *
 *  333proj is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  333proj is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with 333proj.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _HW4_EVENTLOOPHANDLER_H_
#define _HW4_EVENTLOOPHANDLER_H_

namespace hw4 {

// Forward declaration of this class, so that we don't need to include
// EventLoop.h and have an #include loop.
class EventLoop;

// An EventLoopHandler is an abstract base class representing an event
// handler.  Customers subclass EventLoopHandler and register their
// object instances with an EventLoop.  When the handler is
// unregistered, the event loop will call "delete" on the handler.
class EventLoopHandler {
 public:
  virtual ~EventLoopHandler() { }

  // This "pure virtual" member function must be implemented
  // by subclasses.  The EventLoop invokes this function on a
  // registered EventLoopHandler when an event fires on the registered
  // fd. The "eventfield" argument is a logical-or of bitmasks from
  // the EventLoop::eventtype enum.
  virtual void Handle(const int fd,
                      const unsigned int eventfield,
                      EventLoop *looper) = 0;

  // This "pure virtual" member function must also be implemented
  // by subclasses.  It is invoked if the EventLoop is shutting
  // down (because somebody called 'Quit()' on it), but this
  // EventLoopHandler is still registered.  After Quitting() returns,
  // the event loop will delete the handler.
  virtual void Quitting(const int fd) = 0;
};

}  // namespace hw4

#endif  // _HW4_EVENTLOOPHANDLER_H_