SGSharedPtr.hxx

/* -*-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"


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

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