#ifndef BOOST_STATECHART_DETAIL_COUNTED_BASE_HPP_INCLUDED

#define BOOST_STATECHART_DETAIL_COUNTED_BASE_HPP_INCLUDED

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

// Copyright 2002-2006 Andreas Huber Doenni

// 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)

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







#include <boost/detail/atomic_count.hpp>

#include <boost/config.hpp> // BOOST_NO_ARGUMENT_DEPENDENT_LOOKUP







namespace boost

{

namespace statechart

{

namespace detail

{





  

template< bool NeedsLocking >

struct count_base

{

  count_base() : count_( 0 ) {}

  mutable boost::detail::atomic_count count_;

};



template<>

struct count_base< false >

{

  count_base() : count_( 0 ) {}

  mutable long count_;

};



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

template< bool NeedsLocking = true >

class counted_base : private count_base< NeedsLocking >

{

  typedef count_base< NeedsLocking > base_type;

  public:

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

    bool ref_counted() const

    {

      return base_type::count_ != 0;

    }



    long ref_count() const

    {

      return base_type::count_;

    }



  protected:

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

    counted_base() {}

    ~counted_base() {}



    // do nothing copy implementation is intentional (the number of

    // referencing pointers of the source and the destination is not changed

    // through the copy operation)

    counted_base( const counted_base & ) {}

    counted_base & operator=( const counted_base & ) { return *this; }



  public:

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

    // The following declarations should be private.

    // They are only public because many compilers lack template friends.

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

    void add_ref() const

    {

      ++base_type::count_;

    }



    bool release() const

    {

      BOOST_ASSERT( base_type::count_ > 0 );

      return --base_type::count_ == 0;

    }

};







} // namespace detail

} // namespace statechart

} // namespace boost







#endif

