singleton.h

浙江大学的悟空嵌入式系统模拟器

/**
 *  Copyright (c) 2005 Zhejiang University, P.R.China
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */ 

//=============================================================================
/**
 *  \class   PPC_Singleton
 *
 *  \brief   Singleton holder
 *
 *  \author  Chenfeng Zhou <[e-mail]>
 *
 *  Last update: <2005-02-09 22:07:06 by Cheney Chow>
 *  
 *  $Id: Singleton.h,v 1.1 2005/06/16 06:06:36 qilj Exp $
 */
//=============================================================================

#ifndef _PPC_SINGLETON_H_
#define _PPC_SINGLETON_H_

namespace PPC
{
	//! We use template to generalize all the types need to have
	//! only one instance;
    template<typename TYPE>
    class PPC_Singleton
    {
    public:
		static TYPE *instance ()
		{
			if (NULL == singleton_instance_) {
				singleton_instance_ = new PPC_Singleton<TYPE>();
			}

			return &singleton_instance_->instance_;
		}
        
    private:
		PPC_Singleton () {}
		~PPC_Singleton () {}

    private:
        static PPC_Singleton<TYPE> *singleton_instance_;
        TYPE instance_;
    };

	template<typename TYPE>
	PPC_Singleton<TYPE> *PPC_Singleton<TYPE>::singleton_instance_ = NULL;

} //namespace PPC


#endif  // _PPC_SINGLETON_H_