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#ifndef MISC_REFCOUNT_H
#define MISC_REFCOUNT_H
/*
GLT OpenGL C++ Toolkit (LGPL)
Copyright (C) 2000-2002 Nigel Stewart
Email: nigels@nigels.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
*/
/*! \file
\brief Templated reference-counting pointer
\ingroup Misc
*/
#include "glt_config.h"
#include <cassert>
/*! \class ReferenceCountPtr
\brief Templated reference-counting pointer
\ingroup Misc
Dynamically allocated objects (created via 'new') that
are managed via ReferenceCountPtr are automatically
destroyed when the last pointer is destroyed. Therefore,
a reference-counted object can be shared in different
places in the system and will not be leaked or a dangling
(invalid) pointer.
A count of the number of pointers to the object is
maintained, and when this count reaches zero, the
object is destroyed.
In a way, ReferenceCountPtr is a safer version of
std::auto_ptr.
*/
template<class T>
class ReferenceCountPtr
{
public:
/// Default constructor
ReferenceCountPtr()
: _obj(NULL), _count(NULL)
{
}
/// Constructor
ReferenceCountPtr(T *obj)
: _obj(obj), _count(new int)
{
*_count = 0;
inc();
}
/// Copy constructor
ReferenceCountPtr(const ReferenceCountPtr &ptr)
: _obj(ptr._obj), _count(ptr._count)
{
inc();
}
/// Destructor
~ReferenceCountPtr()
{
dec();
}
/// Assignment operator
ReferenceCountPtr &operator=(const ReferenceCountPtr &ptr)
{
dec();
_count = ptr._count;
_obj = ptr._obj;
inc();
return *this;
}
/// Reset the pointer
void clear() { dec(); }
/// Reset the pointer
void reset() { dec(); }
/// Dereference the pointer
inline T &operator*() { assert(_obj); return *_obj; }
/// Dereference the pointer
inline T *operator->() { assert(_obj); return _obj; }
/// Dereference the pointer
inline T *get() { return _obj; }
/// Dereference the pointer
inline const T &operator*() const { assert(_obj); return *_obj; }
/// Dereference the pointer
inline const T *operator->() const { assert(_obj); return _obj; }
/// Dereference the pointer
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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