---

base_smart_pointer.hh

/*
*  Name:      base_smart_pointer.hh
*  Author:    Rafael Jesus Alcantara Perez
*  Summary:   Base class for smart pointers
*  Date:      $Date: 2003/04/14 00:18:31 $
*  Revision:  $Revision: 1.1 $
*
*  Copyright (C) 2001-2002  Rafael Jesus Alcantara Perez <rafa@dedalo-ing.com>
*
*  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., 59 Temple Place, Suite 330, Boston,
*  MA 02111-1307, USA.
*/

#ifndef _MPCL_MEMORY_BASE_SMART_POINTER__
#define _MPCL_MEMORY_BASE_SMART_POINTER__

#include "../exceptions.hh"


namespace mpcl
{

  namespace memory
  {

    class TSharedCell
    {

      public:

        long unsigned int   luiReferenceCount;

        void*   pvItem;


      public:

        //
        //  C O N S T R U C T O R S
        //

        TSharedCell (void)         :
          luiReferenceCount (0L)   ,
          pvItem            (NULL) {}

        TSharedCell (const void* pkvITEM)                 :
          luiReferenceCount (1L)                          ,
          pvItem            (const_cast<void*> (pkvITEM)) {}

    };  // struct TSharedCell

    class TBaseSmartPointer
    {

      protected:

        typedef
          const TSharedCell&
          cell_const_reference;

        typedef
          TSharedCell*
          cell_pointer;

        typedef
          TSharedCell&
          cell_reference;

        mutable cell_pointer   ptSharedCell;


      public:

        typedef
          TSharedCell
          cell_type;


      protected:

        //
        //  C O N S T R U C T O R S
        //

        void attachTo (const TBaseSmartPointer& rkqtBASE_SMART_POINTER)
        {
          ptSharedCell = rkqtBASE_SMART_POINTER.ptSharedCell;
          if ( ptSharedCell )
          {
            ++(ptSharedCell->luiReferenceCount);
          }
        }


      public:

        //
        //  C O N S T R U C T O R S
        //

        TBaseSmartPointer (void)
          throw()             :
          ptSharedCell (NULL) {}

        virtual ~TBaseSmartPointer (void) {}


      public:

        //
        //  S E L E C T O R S
        //

        const void* address (void) const throw()
        {
          const void*   pkvRet = NULL;

          if ( ptSharedCell )
          {
            pkvRet = ptSharedCell->pvItem;
          }
          return pkvRet;
        }

        bool equal (const TBaseSmartPointer& rkqtBASE_SMART_POINTER) const
          throw()
        {
          //
          //  Checks that both  smart pointers  point to the  same cell and that both
          //  pointers are not null.
          //
          register bool   gEqual = ( !ptSharedCell && !rkqtBASE_SMART_POINTER.ptSharedCell );

          if ( ptSharedCell && rkqtBASE_SMART_POINTER.ptSharedCell )
          {
            gEqual = ( ptSharedCell->pvItem == rkqtBASE_SMART_POINTER.ptSharedCell->pvItem );
          }
          return gEqual;
        }

        bool isNull (void) const throw()
        {
          return ( ptSharedCell == NULL );
        }

        long unsigned int references (void) const
          throw (TConstraintException)
        {
          if ( !ptSharedCell )
          {
            throw TConstraintException ("null pointer", __FILE__, __LINE__);
          }
          return ptSharedCell->luiReferenceCount;
        }

    };  // class TBaseSmartPointer

  }  // namespace memory

}  // namespace mpcl


#endif  // not _MPCL_MEMORY_BASE_SMART_POINTER__

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