CrystalSpace

Public API Reference

csutil/weakref.h

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00001 /*
00002   Crystal Space Weak Reference
00003   Copyright (C) 2003 by Jorrit Tyberghein and Matthias Braun
00004 
00005   This library is free software; you can redistribute it and/or
00006   modify it under the terms of the GNU Library General Public
00007   License as published by the Free Software Foundation; either
00008   version 2 of the License, or (at your option) any later version.
00009 
00010   This library is distributed in the hope that it will be useful,
00011   but WITHOUT ANY WARRANTY; without even the implied warranty of
00012   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013   Library General Public License for more details.
00014 
00015   You should have received a copy of the GNU Library General Public
00016   License along with this library; if not, write to the Free
00017   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00018 */
00019 
00020 #ifndef __CS_WEAKREF_H__
00021 #define __CS_WEAKREF_H__
00022 
00027 #include "csextern.h"
00028 #include "csutil/ref.h"
00029 
00030 struct iBase;
00031 
00049 template <class T>
00050 class csWeakRef
00051 {
00052 private:
00053   union
00054   {
00055     T* obj;
00056     void* obj_void;
00057   };
00058 
00064   void Unlink ()
00065   {
00066     if (obj) obj->RemoveRefOwner (&obj_void);
00067   }
00068 
00072   void Link ()
00073   {
00074     if (obj) obj->AddRefOwner (&obj_void);
00075   }
00076 
00077 public:
00081   csWeakRef () : obj (0) {}
00082 
00086   csWeakRef (T* newobj)
00087   {
00088     obj = newobj;
00089     Link ();
00090   }
00091 
00095   csWeakRef (csRef<T> const& newobj)
00096   {
00097     obj = newobj;
00098     Link ();
00099   }
00100 
00104   csWeakRef (csWeakRef const& other) : obj (other.obj)
00105   {
00106     Link ();
00107   }
00108 
00113   csWeakRef (const csPtr<T>& newobj)
00114   {
00115     csRef<T> r = newobj;
00116     obj = r;
00117     Link ();
00118   }
00119 
00123   ~csWeakRef ()
00124   {
00125     Unlink ();
00126   }
00127 
00131   csWeakRef& operator = (T* newobj)
00132   {
00133     if (obj != newobj)
00134     {
00135       Unlink ();
00136       obj = newobj;
00137       Link ();
00138     }
00139     return *this;
00140   }
00141 
00145   csWeakRef& operator = (csRef<T> const& newobj)
00146   {
00147     if (newobj != obj)
00148     {
00149       Unlink ();
00150       obj = newobj;
00151       Link ();
00152     }
00153     return *this;
00154   }
00155 
00160   csWeakRef& operator = (csPtr<T> newobj)
00161   {
00162     csRef<T> r = newobj;
00163     if (obj != r)
00164     {
00165       Unlink ();
00166       obj = r;
00167       Link ();
00168     }
00169     return *this;
00170   }
00171 
00175   csWeakRef& operator = (csWeakRef const& other)
00176   {
00177     this->operator=(other.obj);
00178     return *this;
00179   }
00180 
00182   inline friend bool operator == (const csWeakRef& r1, const csWeakRef& r2)
00183   {
00184     return r1.obj == r2.obj;
00185   }
00187   inline friend bool operator != (const csWeakRef& r1, const csWeakRef& r2)
00188   {
00189     return r1.obj != r2.obj;
00190   }
00192   inline friend bool operator == (const csWeakRef& r1, T* obj)
00193   {
00194     return r1.obj == obj;
00195   }
00197   inline friend bool operator != (const csWeakRef& r1, T* obj)
00198   {
00199     return r1.obj != obj;
00200   }
00202   inline friend bool operator == (T* obj, const csWeakRef& r1)
00203   {
00204     return r1.obj == obj;
00205   }
00207   inline friend bool operator != (T* obj, const csWeakRef& r1)
00208   {
00209     return r1.obj != obj;
00210   }
00211 
00213   T* operator -> () const
00214   { return obj; }
00215   
00217   operator T* () const
00218   { return obj; }
00219   
00221   T& operator* () const
00222   { return *obj; }
00223 
00228   bool IsValid () const
00229   { return (obj != 0); }
00230 };
00231 
00232 #endif // __CS_WEAKREF_H__
00233 

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