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# 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