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// Copyright (c) 1999 Utrecht University (The Netherlands),
// ETH Zurich (Switzerland), Freie Universitaet Berlin (Germany),
// INRIA Sophia-Antipolis (France), Martin-Luther-University Halle-Wittenberg
// (Germany), Max-Planck-Institute Saarbruecken (Germany), RISC Linz (Austria),
// and Tel-Aviv University (Israel). All rights reserved.
//
// This file is part of CGAL (www.cgal.org); 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; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.2-branch/Kernel_23/include/CGAL/Handle_for_virtual.h $
// $Id: Handle_for_virtual.h 28567 2006-02-16 14:30:13Z lsaboret $
//
//
// Author(s) : Stefan Schirra
#ifndef CGAL_HANDLE_FOR_VIRTUAL_H
#define CGAL_HANDLE_FOR_VIRTUAL_H
#include <CGAL/basic.h>
#include <typeinfo>
CGAL_BEGIN_NAMESPACE
class Ref_counted_virtual
{
public:
Ref_counted_virtual() : count(1) {}
Ref_counted_virtual(const Ref_counted_virtual&) : count(1) {}
void add_reference() { ++count; }
void remove_reference() { --count; }
bool is_referenced() const { return (count != 0); }
bool is_shared() const { return (count > 1); }
virtual const std::type_info & type() const
{ return typeid(void); }
virtual const void * object_ptr() const
{ return NULL; }
virtual ~Ref_counted_virtual() {}
protected:
unsigned int count;
};
template <class RefCounted>
// RefCounted must provide
// add_reference()
// remove_reference()
// bool is_referenced() const
// bool is_shared() const
// and initialize count to 1 in default and copy constructor
class Handle_for_virtual
{
public:
Handle_for_virtual(const RefCounted& rc)
{
ptr = new RefCounted(rc);
}
Handle_for_virtual()
{
ptr = NULL;
}
Handle_for_virtual( const Handle_for_virtual& h)
{
ptr = h.ptr;
ptr->add_reference();
}
~Handle_for_virtual()
{
ptr->remove_reference();
if ( !ptr->is_referenced() )
delete ptr;
}
Handle_for_virtual&
operator=( const Handle_for_virtual& h)
{
h.ptr->add_reference();
ptr->remove_reference();
if ( !ptr->is_referenced() )
delete ptr;
ptr = h.ptr;
return *this;
}
// protected:
typedef RefCounted element_type;
template <class T>
void
initialize_with( const T& rc)
{
ptr = new T(rc);
}
bool
identical( const Handle_for_virtual& h) const
{ return ptr == h.ptr; }
long int
id() const
{ return reinterpret_cast<long int>(&*ptr); }
const RefCounted *
Ptr() const
{ return ptr; }
const void * object_ptr() const
{
return ptr->object_ptr();
}
/*
T *
Ptr()
{
copy_on_write();
return ptr;
}
*/
/*
// private:
void
copy_on_write()
{
if ( ptr->is_shared() )
{
RefCounted* tmp_ptr = allocator.allocate(1);
allocator.construct( tmp_ptr, *ptr);
ptr->remove_reference();
ptr = tmp_ptr;
}
}
*/
protected:
/*
RefCounted * ptr() const
{
return ptr;
}
*/
private:
RefCounted * ptr;
};
CGAL_END_NAMESPACE
#endif // CGAL_HANDLE_FOR_VIRTUAL_H
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