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/* Copyright (c) 2000 MBARI                                                 */
/* MBARI Proprietary Information. All rights reserved.                      */
/****************************************************************************/
/* Summary  :                                                               */
/* Filename : EventService.h                                                */
/* Author   :                                                               */
/* Project  :                                                               */
/* Version  : 1.0                                                           */
/* Created  : 02/07/2000                                                    */
/* Modified :                                                               */
/* Archived :                                                               */
/****************************************************************************/
/* Modification History:                                                    */
/****************************************************************************/
#ifndef _EVENTSERVICE_H
#define _EVENTSERVICE_H

#include "DynamicArray.h"
#include "Task.h"
#include "TaskInterface.h"


/*
CLASS 
EventService

DESCRIPTION
Allows application to subscribe to one or more events from one or
more TaskInterface objects. For each subscribed event, the application
specifies a callback method to be invoked.

The specified callback method must have the following signature:

  void Task::callback(TaskInterface *client, EventCode eventCode);

The first argument is a pointer to the TaskInterface object that 
published the event. The second argument is the EventCode of the
event.


AUTHOR
Tom O'Reilly
*/
class EventService {
public:

  EventService(const char *name, Task *task);

  ~EventService();

  const char *name() {
    return _name;
  }

  ///////////////////////////////////////////////////////////////////
  // Prototype for event callback methods
  typedef void (Task::*Callback)(TaskInterface *client, 
				 EventCode eventCode);

  ///////////////////////////////////////////////////////////////////
  // Subscribe to specified event on specified TaskInterface, and
  // "register" callback to be invoked when event occurs.
  void subscribe(TaskInterface *taskInterface, 
		 EventCode eventCode, 
		 Callback callback);


  ///////////////////////////////////////////////////////////////////
  // Wait for event from subscribed TaskInterfaces, and invoke
  // appropriate calback
  void processEvent();

private:

  const char *_name;

  struct EventTableEntry {

    EventTableEntry(TaskInterface *proxy, 
		    EventCode eventCode,
		    Callback callback) {
      _proxy = proxy;
      _eventCode = eventCode;
      _callback = callback;
    }

    TaskInterface *_proxy;
    EventCode _eventCode;
    Callback _callback;
  };

  Task *_task;

  DynamicArray<EventTableEntry *> _eventTable;
};

#endif