include/wx/tracker.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/tracker.h
   3 // Purpose:     Support class for object lifetime tracking (wxWeakRef<T>)
   4 // Author:      Arne Steinarson
   5 // Created:     28 Dec 07
   6 // RCS-ID:      $Id$
   7 // Copyright:   (c) 2007 Arne Steinarson
   8 // Licence:     wxWindows licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_TRACKER_H_
  12 #define _WX_TRACKER_H_
  13
  14 #include "wx/defs.h"
  15
  16 class wxEventConnectionRef;
  17
  18 // This class represents an object tracker and is stored in a linked list
  19 // in the tracked object. It is only used in one of its derived forms.
  20 class WXDLLIMPEXP_BASE wxTrackerNode
  21 {
  22 public:
  23     wxTrackerNode() : m_nxt(NULL) { }
  24     virtual ~wxTrackerNode() { }
  25
  26     virtual void OnObjectDestroy() = 0;
  27
  28     virtual wxEventConnectionRef *ToEventConnection() { return NULL; }
  29
  30 private:
  31     wxTrackerNode *m_nxt;
  32
  33     friend class wxTrackable;        // For list access
  34     friend class wxEvtHandler;       // For list access
  35 };
  36
  37 // Add-on base class for a trackable object.
  38 class wxTrackable
  39 {
  40 public:
  41     wxTrackable() : m_first(NULL) { }
  42
  43     ~wxTrackable()
  44     {
  45         // Notify all registered refs
  46         while ( m_first )
  47         {
  48             wxTrackerNode * const first = m_first;
  49             m_first = first->m_nxt;
  50             first->OnObjectDestroy();
  51         }
  52     }
  53
  54     void AddNode(wxTrackerNode *prn)
  55     {
  56         prn->m_nxt = m_first;
  57         m_first = prn;
  58     }
  59
  60     void RemoveNode(wxTrackerNode *prn)
  61     {
  62         for ( wxTrackerNode **pprn = &m_first; *pprn; pprn = &(*pprn)->m_nxt )
  63         {
  64             if ( *pprn == prn )
  65             {
  66                 *pprn = prn->m_nxt;
  67                 return;
  68             }
  69         }
  70
  71         wxFAIL_MSG( "removing invalid tracker node" );
  72     }
  73
  74     wxTrackerNode *GetFirst() const { return m_first; }
  75
  76 protected:
  77     wxTrackerNode *m_first;
  78
  79     DECLARE_NO_COPY_CLASS(wxTrackable)
  80 };
  81
  82 #endif // _WX_TRACKER_H_
  83