MEM_RefCountPtr.h

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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.
 *
 * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#ifndef NAN_INCLUDED_MEM_RefCountPtr_h
#define NAN_INCLUDED_MEM_RefCountPtr_h

#include <stdlib.h> // for NULL !

class MEM_RefCountable {
private :

    mutable int m_count;

protected :

    MEM_RefCountable (
    ) :
        m_count (0)
    {
    };

    MEM_RefCountable (
        const MEM_RefCountable &
    ) :
        m_count (0)
    {
    }

public :

        void
    IncRef(
    ) const {
        m_count++;
    }

        int
    DecRef(
    ) {
        return (--m_count);
    }

    ~MEM_RefCountable(
    ) {
        //nothing to do
    }
};

template
    < class T >
class MEM_RefCountPtr {

public :

    MEM_RefCountPtr(
        const MEM_RefCountPtr &rhs
    ) : m_val (NULL) {
        ShareOwnership(rhs.m_val);
    }

    MEM_RefCountPtr(
        const T* val
    ) :
        m_val (NULL)
    {
        ShareOwnership(val);
    }

    MEM_RefCountPtr(
    ) :
        m_val (NULL)
    {
    }

    operator T * () const {
        return m_val;
    }


    MEM_RefCountPtr & operator=(
        const MEM_RefCountPtr &rhs
    ) {
        if (this->m_val != rhs.m_val) {
            ReleaseOwnership();
            ShareOwnership(rhs.m_val);
        }
        return *this;
    }

    T * operator->() const {
        return m_val;
    }

        T&
    Ref(
    ) {
        return *m_val;
    }


    ~MEM_RefCountPtr(
    ) {
        ReleaseOwnership();
    }

private :
    
    T * m_val;

        void
    ShareOwnership(
        const T * val
    ) {
        if (val != NULL) {
            val->IncRef();
        }
        m_val = const_cast<T *>(val);
    }
        
        void
    ReleaseOwnership(
    ) {
        if (m_val) {
            if (m_val->DecRef() == 0) {
                delete(m_val);
                m_val = NULL;
            }
        }
    }

};

#endif