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ref_ptr.h

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/* ====================================================================
 *              The CBITS Software License, Version 1.0
 *
 *               Copyright (c) 2002-2003 Bruce Lowery
 *                       All rights reserved
 *
 * Redistribution and use of this software, in source and binary forms, 
 * with or without modification, are permitted provided that the above 
 * copyright notice, this paragraph, and the following paragraph are 
 * retained in each source code file.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL BRUCE LOWERY OR OTHER CONTRIBUTORS 
 * TO THE CBITS LIBRARY BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 */
#ifndef __REF_PTR_H__
#define __REF_PTR_H__

#include <stdlib.h>

#ifdef USE_PTHREADS
#include <pthread.h>
#elif defined WIN32
#include <winnt.h>
#endif

namespace cbits
{

template< typename T >
class ref_ptr
{
public:

    ref_ptr<T>( T* t ) : _t(t),_refs(new long)
    {
        *(_refs) = 1;
#ifdef USE_PTHREADS
        _lock = new pthread_mutex_t;
        pthread_mutex_init( _lock, 0 );
#elif defined WIN32
        _lock = CreateMutex( 0, FALSE, 0 );
#endif
    }


    ref_ptr<T>( const ref_ptr<T>& r )
    {
        r.lock();
        _t = r._t;
        _refs = r._refs;
        _lock = r._lock;
        (*_refs)++;
        r.unlock();
    }


    ref_ptr<T>& operator=( const ref_ptr<T>& r )
    {
        if( _t == r._t )
        {
            return *this;
        }

        r.lock();
        (*r._refs)++;

        lock();
        (*_refs)--;
        int n = *_refs;
        unlock();

        if( 0 == n )
        {
            freeObject();
        }

        _t = r._t;
        _refs = r._refs;
        _lock = r._lock;
        r.unlock();
        return *this;
    }


    const long getRefCount() const
    {
        lock();
        long n = *_refs;
        unlock();
        return n;
    }


    bool operator==( const ref_ptr<T>& r )
    {
        return _t == r._t;
    }


    T* operator->()
    {
        return _t;
    }


    T& operator*()
    {
        return *_t;
    }


    virtual ~ref_ptr<T>()
    {
        lock();
        (*_refs)--;
        int n = *_refs;
        unlock();

        if( 0 == n )
        {
            freeObject();
        }
    }


protected:

    T* _t;       
    long* _refs; 
private:

    void freeObject()
    {
        delete _t;
        delete _refs;
#if defined USE_PTHREADS 
        delete _lock;
#elif defined WIN32
        CloseHandle( _lock );
#endif
    }

    void lock() const
    {
#ifdef USE_PTHREADS
        pthread_mutex_lock( _lock );
#elif defined(WIN32)
        WaitForSingleObject( _lock, INFINITE );
#endif

    }

    void unlock() const
    {
#ifdef USE_PTHREADS
        pthread_mutex_unlock( _lock );
#elif defined(WIN32)
        ReleaseMutex( _lock );
#endif
    }

#ifdef USE_PTHREADS
    mutable pthread_mutex_t * _lock;  
#elif defined(WIN32)
    HANDLE _lock;                     
#endif
};

};

#endif

/*
 * $Id: ref_ptr.h,v 1.5 2002/10/15 03:13:54 brulow Exp $
 *
 * History: (Add nothing manually below)
 * -----------------------------------------------------------------------
 *
 * $Log: ref_ptr.h,v $
 * Revision 1.5  2002/10/15 03:13:54  brulow
 * Fix unit tests
 *
 * Revision 1.4  2002/10/14 01:36:54  brulow
 * Add pointer pkg documentation
 *
 * Revision 1.3  2002/10/14 01:21:04  brulow
 * Add unit tests for pointer pkg
 *
 * Revision 1.2  2002/10/13 20:12:59  brulow
 * *** empty log message ***
 *
 * Revision 1.1  2002/10/13 15:19:58  brulow
 * Add 'smart, ref counting' pointer.
 *
 *
 */

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