/* 
 * PPOGL - PlanetPenguin Open Game Library
 * Copyright (C) 2005 Volker Stroebel <volker@planetpenguin.de>
 * 
 * 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 2.1
 * 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 General Public License for more details.
 * 
 * You should have received a copy of the GNU 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.
 */
 
#ifndef _PPOGL_SINGLETON_H_
#define _PPOGL_SINGLETON_H_

#include "assert.h"

namespace ppogl{

/// Template class for creating singletons
template <class T>
class Singleton
{
public:
	static T&
	getInstance()
	/// create the instance if necessary and returns a reference of the instance
	{
		if(sm_instance==0){
			sm_instance = new T;
			PP_ENSURE(sm_instance!=NULL,"Unable to create singleton instance")
		}
		return *sm_instance;
	}
	
	static T*
	getInstancePtr()
	/// create the instance if necessary and returns a pointer to the instance
	{
		if(sm_instance==0){
			sm_instance = new T;
			PP_ENSURE(sm_instance!=NULL,"Unable to create singleton instance")
		}
		return sm_instance;
	}
	
protected:
	Singleton(){};
	virtual ~Singleton(){};
		
private:
	static T* sm_instance;

};

} //namespace ppogl

/// creates the static pointer for the instance and is necessary for each singleton
#define PPOGL_SINGLETON(T) template <> T* ppogl::Singleton<T>::sm_instance = NULL

#endif // _PPOGL_SINGLETON_H_