Public API Reference

csutil/weakref.h

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/*
  Crystal Space Weak Reference
  Copyright (C) 2003 by Jorrit Tyberghein and Matthias Braun

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Library General Public
  License as published by the Free Software Foundation; either
  version 2 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Library General Public License for more details.

  You should have received a copy of the GNU Library General Public
  License along with this library; if not, write to the Free
  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef __CS_WEAKREF_H__
#define __CS_WEAKREF_H__

#include "csextern.h"
#include "csutil/ref.h"

struct iBase;

template <class T>
class csWeakRef
{
private:
  union
  {
    T* obj;
    void* obj_void;
  };

  void Unlink ()
  {
    if (obj) obj->RemoveRefOwner (&obj_void);
  }

  void Link ()
  {
    if (obj) obj->AddRefOwner (&obj_void);
  }

public:
  csWeakRef () : obj (0) {}

  csWeakRef (T* newobj)
  {
    obj = newobj;
    Link ();
  }

  csWeakRef (csRef<T> const& newobj)
  {
    obj = newobj;
    Link ();
  }

  csWeakRef (csWeakRef const& other) : obj (other.obj)
  {
    Link ();
  }

  csWeakRef (const csPtr<T>& newobj)
  {
    csRef<T> r = newobj;
    obj = r;
    Link ();
  }

  ~csWeakRef ()
  {
    Unlink ();
  }

  csWeakRef& operator = (T* newobj)
  {
    if (obj != newobj)
    {
      Unlink ();
      obj = newobj;
      Link ();
    }
    return *this;
  }

  csWeakRef& operator = (csRef<T> const& newobj)
  {
    if (newobj != obj)
    {
      Unlink ();
      obj = newobj;
      Link ();
    }
    return *this;
  }

  csWeakRef& operator = (csPtr<T> newobj)
  {
    csRef<T> r = newobj;
    if (obj != r)
    {
      Unlink ();
      obj = r;
      Link ();
    }
    return *this;
  }

  csWeakRef& operator = (csWeakRef const& other)
  {
    this->operator=(other.obj);
    return *this;
  }

  inline friend bool operator == (const csWeakRef& r1, const csWeakRef& r2)
  {
    return r1.obj == r2.obj;
  }
  inline friend bool operator != (const csWeakRef& r1, const csWeakRef& r2)
  {
    return r1.obj != r2.obj;
  }
  inline friend bool operator == (const csWeakRef& r1, T* obj)
  {
    return r1.obj == obj;
  }
  inline friend bool operator != (const csWeakRef& r1, T* obj)
  {
    return r1.obj != obj;
  }
  inline friend bool operator == (T* obj, const csWeakRef& r1)
  {
    return r1.obj == obj;
  }
  inline friend bool operator != (T* obj, const csWeakRef& r1)
  {
    return r1.obj != obj;
  }

  T* operator -> () const
  { return obj; }
  
  operator T* () const
  { return obj; }
  
  T& operator* () const
  { return *obj; }

  bool IsValid () const
  { return (obj != 0); }
};

#endif // __CS_WEAKREF_H__

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