Singleton.h

/*
-----------------------------------------------------------------------------
This source file is part of OpenSpace3D
For the latest info, see http://www.openspace3d.com

Copyright (c) 2012 I-maginer

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

This program 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt

-----------------------------------------------------------------------------
*/

#ifndef __SINGLETON_H__
#define __SINGLETON_H__

#include "../lib/common.h"

template <typename DERIVATED_CLASS> class Singleton
{
  public:
  protected:    
    static DERIVATED_CLASS* instance;
  private:

  public:
    Singleton();

    ~Singleton();

    static DERIVATED_CLASS& GetSingleton();

    static DERIVATED_CLASS* GetSingletonPtr();
  protected:
  private:
};

template <class DERIVATED_CLASS> inline Singleton<DERIVATED_CLASS>::Singleton()
{
  assert(!Singleton<DERIVATED_CLASS>::instance);
  #if defined(_MSC_VER) && _MSC_VER < 1200       
    int offset = (int)(DERIVATED_CLASS*)1 - (int)(Singleton <DERIVATED_CLASS>*)(DERIVATED_CLASS*)1;
    Singleton<DERIVATED_CLASS>::instance = (DERIVATED_CLASS*)((int)this + offset);
  #else
    Singleton<DERIVATED_CLASS>::instance = static_cast<DERIVATED_CLASS*>(this);
  #endif
};

template <class DERIVATED_CLASS> inline Singleton<DERIVATED_CLASS>::~Singleton()
{
  assert(Singleton<DERIVATED_CLASS>::instance);
  Singleton<DERIVATED_CLASS>::instance = 0;
};

template <class DERIVATED_CLASS> DERIVATED_CLASS& Singleton<DERIVATED_CLASS>::GetSingleton()
{
  assert(Singleton<DERIVATED_CLASS>::instance);
  return (*Singleton<DERIVATED_CLASS>::instance);
};

template <class DERIVATED_CLASS> DERIVATED_CLASS* Singleton<DERIVATED_CLASS>::GetSingletonPtr()
{
  return Singleton<DERIVATED_CLASS>::instance;
};

#endif