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misc/refcount.h

Go to the documentation of this file.

#ifndef MISC_REFCOUNT_H
#define MISC_REFCOUNT_H

/*

  GLT OpenGL C++ Toolkit (LGPL)
  Copyright (C) 2000-2002 Nigel Stewart  

  Email: nigels.com@gmail.com   
  WWW:   http://www.nigels.com/glt/

  This library 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 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/

#include <glt/config.h>

#include <cassert>

template<class T>
class ReferenceCountPtr
{
public:

    ReferenceCountPtr()
    : _obj(NULL), _count(NULL)
    {
    }

    ReferenceCountPtr(T *obj)
    : _obj(obj), _count(new int)
    {
        *_count = 0;
        inc();
    }
    
    ReferenceCountPtr(const ReferenceCountPtr &ptr)
    : _obj(ptr._obj), _count(ptr._count)
    {
        inc();
    }

    ~ReferenceCountPtr()
    {
        dec();
    }

    ReferenceCountPtr &operator=(const ReferenceCountPtr &ptr)
    {
        dec();

        _count = ptr._count;
        _obj   = ptr._obj;

        inc();

        return *this;
    }

    void clear() { dec(); }
    void reset() { dec(); }

    inline T &operator*()              { assert(_obj); return *_obj; }
    inline T *operator->()             { assert(_obj); return  _obj; }
    inline T *get()                    { return _obj; }

    inline const T &operator*()  const { assert(_obj); return *_obj; }
    inline const T *operator->() const { assert(_obj); return  _obj; }
    inline const T *get()        const { return _obj; }

private:
    T   *_obj;
    int *_count;

    void inc() 
    { 
        if (_count) 
            (*_count)++; 
    }

    void dec() 
    {
        if (_count)
        {
            (*_count)--;
            if (*_count==0)
            {
                delete _obj;
                delete _count;
            }
        }

        _obj  = NULL;
        _count = NULL;
    }
};

#endif

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