mapnik/src/ptr.hh

/* This file is part of Mapnik (c++ mapping toolkit)
 * Copyright (C) 2005 Artem Pavlenko
 *
 * Mapnik 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 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.
 */

//$Id: ptr.hh 58 2004-10-31 16:21:26Z artem $

#ifndef PTR_HH
#define PTR_HH

namespace mapnik
{

    template <typename T> struct DefaultDeletePolicy
    {
        static void destroy(T* p)
        {
            delete p;
        }
    };

    template <typename T,
        template <typename T> class DeallocPolicy=DefaultDeletePolicy>
        class ref_ptr
    {
        private:
            T* ptr_;
            int* pCount_;
        public:
            T* operator->() {return ptr_;}
            const T* operator->() const {return ptr_;}
            T* get() {return ptr_;}
            const T* get() const {return ptr_;}
            const T& operator *() const {return *ptr_;}
            explicit ref_ptr(T* ptr=0)
                :ptr_(ptr),pCount_(new int(1)) {}
            ref_ptr(const ref_ptr& rhs)
                :ptr_(rhs.ptr_),pCount_(rhs.pCount_)
            {
                (*pCount_)++;
            }
            ref_ptr& operator=(const ref_ptr& rhs)
            {
                if (ptr_==rhs.ptr_) return *this;
                if (--(*pCount_)==0)
                {
                    DeallocPolicy<T>::destroy(ptr_);
                    delete pCount_;
                }
                ptr_=rhs.ptr_;
                pCount_=rhs.pCount_;
                (*pCount_)++;
                return *this;
            }
            bool operator !() const
            {
                return ptr_==0;
            }
            operator bool () const
            {
                return ptr_!=0;
            }
            inline friend bool operator==(const ref_ptr& lhs,
                const T* rhs)
            {
                return lhs.ptr_==rhs;
            }
            inline friend bool operator==(const T* lhs,
                const ref_ptr& rhs)
            {
                return lhs==rhs.ptr_;
            }
            inline friend bool operator!=(const ref_ptr& lhs,
                const T* rhs)
            {
                return lhs.ptr_!=rhs;
            }
            inline friend bool operator!=(const T* lhs,
                const ref_ptr& rhs)
            {
                return lhs!=rhs.ptr_;
            }
            ~ref_ptr()
            {
                if (--(*pCount_)==0)
                {
                    DeallocPolicy<T>::destroy(ptr_);
                    delete pCount_;
                }
            }
    };
}
#endif                                            //PTR_HH