src/apps/cortex/support/ObservableHandler.h

   1 /*
   2  * Copyright (c) 1999-2000, Eric Moon.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions, and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions, and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * 3. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  23  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  24  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
  27  * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31
  32 // ObservableHandler.h
  33 // * PURPOSE
  34 //   Implementation of an observable BHandler.
  35 //
  36 // * HISTORY
  37 //   e.moon             19aug99         Begun.
  38
  39 #ifndef __ObservableHandler_H__
  40 #define __ObservableHandler_H__
  41
  42 #include <Handler.h>
  43
  44 #include "observe.h"
  45 #include "IObservable.h"
  46 #include "MultiInvoker.h"
  47
  48 #include "cortex_defs.h"
  49 __BEGIN_CORTEX_NAMESPACE
  50
  51 class ObservableHandler :
  52         public  BHandler,
  53         public  IObservable,
  54         private MultiInvoker {
  55
  56         typedef BHandler _inherited;
  57
  58 public:                                                                                 // *** deletion
  59         // clients must call release() rather than deleting,
  60         // to ensure that all observers are notified of the
  61         // object's demise.  if the object has already been
  62         // released, return an error.
  63
  64         virtual status_t release();
  65
  66 public:                                                                                 // *** ctor/dtor
  67         virtual ~ObservableHandler();
  68         ObservableHandler(
  69                 const char*                                                     name=0);
  70         ObservableHandler(
  71                 BMessage*                                                               archive);
  72
  73 public:                                                                                 // *** accessors
  74         // return true if release() has been called, false otherwise.
  75         bool isReleased() const;
  76
  77 protected:                                                                      // *** hooks
  78         // sends M_OBSERVER_ADDED to the newly-added observer
  79         virtual void observerAdded(
  80                 const BMessenger&                               observer);
  81
  82         // sends M_OBSERVER_REMOVED to the newly-removed observer
  83         virtual void observerRemoved(
  84                 const BMessenger&                               observer);
  85
  86 protected:                                                                      // *** internal operations
  87         // call to send the given message to all observers.
  88         // Responsibility for deletion of the message remains with
  89         // the caller.
  90         // * LOCKING: the BLooper must be locked.
  91         virtual status_t notify(
  92                 BMessage*                                                               message);
  93
  94         // sends M_RELEASE_OBSERVABLE
  95         virtual void notifyRelease();
  96
  97 public:                                                                                 // *** BHandler
  98         virtual void MessageReceived(
  99                 BMessage*                                                               message);
 100
 101 public:                                                                                 // *** BArchivable
 102         // * LOCKING: the BLooper must be locked.
 103         virtual status_t Archive(
 104                 BMessage*                                                               archive,
 105                 bool                                                                            deep=true) const;
 106
 107 private:                                                                                // implementation
 108         void _handleAddObserver(
 109                 BMessage*                                                               message); //nyi
 110
 111         void _handleRemoveObserver(
 112                 BMessage*                                                               message); //nyi
 113
 114 private:                                                                                // members
 115         bool                                                                                    m_released;
 116 };
 117
 118 __END_CORTEX_NAMESPACE
 119 #endif /*__ObservableHandler_H__*/
 120