//////////////////////////////////////////////////////////////////////////////

// (c) Copyright Andreas Huber Doenni 2002-2005, Eric Niebler 2006

// Distributed under the Boost Software License, Version 1.0. (See accompany-

// ing file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//////////////////////////////////////////////////////////////////////////////



#ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_COUNTED_BASE_HPP_EAN_04_16_2006

#define BOOST_XPRESSIVE_DETAIL_UTILITY_COUNTED_BASE_HPP_EAN_04_16_2006



#include <boost/assert.hpp>

#include <boost/checked_delete.hpp>

#include <boost/detail/atomic_count.hpp>



namespace boost { namespace xpressive { namespace detail

{

    template<typename Derived>

    struct counted_base_access;



    //////////////////////////////////////////////////////////////////////////////

    // counted_base

    template<typename Derived>

    struct counted_base

    {

        long use_count() const

        {

            return this->count_;

        }



    protected:

        counted_base()

          : count_(0)

        {

        }



        counted_base(counted_base<Derived> const &)

          : count_(0)

        {

        }



        counted_base &operator =(counted_base<Derived> const &)

        {

            return *this;

        }



    private:

        friend struct counted_base_access<Derived>;

        mutable boost::detail::atomic_count count_;

    };



    //////////////////////////////////////////////////////////////////////////////

    // counted_base_access

    template<typename Derived>

    struct counted_base_access

    {

        static void add_ref(counted_base<Derived> const *that)

        {

            ++that->count_;

        }



        static void release(counted_base<Derived> const *that)

        {

            BOOST_ASSERT(0 < that->count_);

            if(0 == --that->count_)

            {

                boost::checked_delete(static_cast<Derived const *>(that));

            }

        }

    };



    template<typename Derived>

    inline void intrusive_ptr_add_ref(counted_base<Derived> const *that)

    {

        counted_base_access<Derived>::add_ref(that);

    }



    template<typename Derived>

    inline void intrusive_ptr_release(counted_base<Derived> const *that)

    {

        counted_base_access<Derived>::release(that);

    }



}}} // namespace boost::xpressive::detail



#endif

