#ifndef BOOST_REF_HPP_INCLUDED

#define BOOST_REF_HPP_INCLUDED

// MS compatible compilers support #pragma once

#if defined(_MSC_VER) && (_MSC_VER >= 1020)

# pragma once

#endif

#include <boost/config.hpp>

#include <boost/utility/addressof.hpp>

#include <boost/mpl/bool.hpp>

#include <boost/detail/workaround.hpp>

//

//  ref.hpp - ref/cref, useful helper functions

//

//  Copyright (C) 1999, 2000 Jaakko Järvi (jaakko.jarvi@cs.utu.fi)

//  Copyright (C) 2001, 2002 Peter Dimov

//  Copyright (C) 2002 David Abrahams

//

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

// accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

//

//  See http://www.boost.org/libs/bind/ref.html for documentation.

//

namespace boost

{

template<class T> class reference_wrapper

{ 

public:

    typedef T type;

#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, < 1300 )

    explicit reference_wrapper(T& t): t_(&t) {}

#else

    explicit reference_wrapper(T& t): t_(boost::addressof(t)) {}

#endif

    operator T& () const { return *t_; }

    T& get() const { return *t_; }

    T* get_pointer() const { return t_; }

private:

    T* t_;

};

# if defined( __BORLANDC__ ) && BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581) )

#  define BOOST_REF_CONST

# else

#  define BOOST_REF_CONST const

# endif

template<class T> inline reference_wrapper<T> BOOST_REF_CONST ref(T & t)

{ 

    return reference_wrapper<T>(t);

}

template<class T> inline reference_wrapper<T const> BOOST_REF_CONST cref(T const & t)

{

    return reference_wrapper<T const>(t);

}

# undef BOOST_REF_CONST

# ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

template<typename T>

class is_reference_wrapper

    : public mpl::false_

{

};

template<typename T>

class unwrap_reference

{

 public:

    typedef T type;

};

#  define AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(X) \

template<typename T> \

class is_reference_wrapper< X > \

    : public mpl::true_ \

{ \

}; \

\

template<typename T> \

class unwrap_reference< X > \

{ \

 public: \

    typedef T type; \

}; \

/**/

AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T>)

#if !defined(BOOST_NO_CV_SPECIALIZATIONS)

AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T> const)

AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T> volatile)

AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF(reference_wrapper<T> const volatile)

#endif

#  undef AUX_REFERENCE_WRAPPER_METAFUNCTIONS_DEF

# else // no partial specialization

} // namespace boost

#include <boost/type.hpp>

namespace boost

{

namespace detail

{

  typedef char (&yes_reference_wrapper_t)[1];

  typedef char (&no_reference_wrapper_t)[2];

  no_reference_wrapper_t is_reference_wrapper_test(...);

  template<typename T>

  yes_reference_wrapper_t is_reference_wrapper_test(type< reference_wrapper<T> >);

  template<bool wrapped>

  struct reference_unwrapper

  {

      template <class T>

      struct apply

      {

          typedef T type;

      };

  };

  template<>

  struct reference_unwrapper<true>

  {

      template <class T>

      struct apply

      {

          typedef typename T::type type;

      };

  };

}

template<typename T>

class is_reference_wrapper

{

 public:

    BOOST_STATIC_CONSTANT(

        bool, value = (

             sizeof(detail::is_reference_wrapper_test(type<T>()))

            == sizeof(detail::yes_reference_wrapper_t)));

    typedef ::boost::mpl::bool_<value> type;

};

template <typename T>

class unwrap_reference

    : public detail::reference_unwrapper<

        is_reference_wrapper<T>::value

      >::template apply<T>

{};

# endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

} // namespace boost

#endif // #ifndef BOOST_REF_HPP_INCLUDED