mfranz
dcb95d131b
- coplied license headers from h(xx) files to respective c(xx) files - removed trailing spaces - fixe $Id$ - fixed typos
100 lines
3.1 KiB
C++
100 lines
3.1 KiB
C++
/* -*-c++-*-
|
|
*
|
|
* Copyright (C) 2005-2006 Mathias Froehlich
|
|
*
|
|
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*
|
|
*/
|
|
|
|
#ifndef SGSharedPtr_HXX
|
|
#define SGSharedPtr_HXX
|
|
|
|
#include "SGReferenced.hxx"
|
|
|
|
/// This class is a pointer proxy doing reference counting on the object
|
|
/// it is pointing to.
|
|
/// The SGSharedPtr class handles reference counting and possible
|
|
/// destruction if no nore references are in use automatically.
|
|
/// Classes derived from @SGReferenced can be handled with SGSharedPtr.
|
|
/// Once you have a SGSharedPtr available you can use it just like
|
|
/// a usual pointer with the exception that you don't need to delete it.
|
|
/// Such a reference is initialized by zero if not initialized with a
|
|
/// class pointer.
|
|
/// One thing you need to avoid are cyclic loops with such pointers.
|
|
/// As long as such a cyclic loop exists the reference count never drops
|
|
/// to zero and consequently the objects will never be destroyed.
|
|
/// Always try to use directed graphs where the references away from the
|
|
/// top node are made with SGSharedPtr's and the back references are done with
|
|
/// ordinary pointers.
|
|
/// There is a very good description of OpenSceneGraphs ref_ptr which is
|
|
/// pretty much the same than this one at
|
|
/// http://dburns.dhs.org/OSG/Articles/RefPointers/RefPointers.html
|
|
|
|
template<typename T>
|
|
class SGSharedPtr {
|
|
public:
|
|
SGSharedPtr(void) : _ptr(0)
|
|
{}
|
|
SGSharedPtr(T* ptr) : _ptr(ptr)
|
|
{ get(_ptr); }
|
|
SGSharedPtr(const SGSharedPtr& p) : _ptr(p.ptr())
|
|
{ get(_ptr); }
|
|
template<typename U>
|
|
SGSharedPtr(const SGSharedPtr<U>& p) : _ptr(p.ptr())
|
|
{ get(_ptr); }
|
|
~SGSharedPtr(void)
|
|
{ put(); }
|
|
|
|
SGSharedPtr& operator=(const SGSharedPtr& p)
|
|
{ assign(p.ptr()); return *this; }
|
|
template<typename U>
|
|
SGSharedPtr& operator=(const SGSharedPtr<U>& p)
|
|
{ assign(p.ptr()); return *this; }
|
|
template<typename U>
|
|
SGSharedPtr& operator=(U* p)
|
|
{ assign(p); return *this; }
|
|
|
|
T* operator->(void) const
|
|
{ return _ptr; }
|
|
T& operator*(void) const
|
|
{ return *_ptr; }
|
|
operator T*(void) const
|
|
{ return _ptr; }
|
|
T* ptr(void) const
|
|
{ return _ptr; }
|
|
|
|
bool isShared(void) const
|
|
{ return SGReferenced::shared(_ptr); }
|
|
unsigned getNumRefs(void) const
|
|
{ return SGReferenced::count(_ptr); }
|
|
|
|
bool valid(void) const
|
|
{ return _ptr; }
|
|
|
|
private:
|
|
void assign(T* p)
|
|
{ get(p); put(); _ptr = p; }
|
|
|
|
void get(const T* p) const
|
|
{ SGReferenced::get(p); }
|
|
void put(void)
|
|
{ if (!SGReferenced::put(_ptr)) { delete _ptr; _ptr = 0; } }
|
|
|
|
// The reference itself.
|
|
T* _ptr;
|
|
};
|
|
|
|
#endif
|