//  (C) Copyright John Maddock 2005.

//  Use, modification and distribution are subject to 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)

#ifndef BOOST_TR1_UTILITY_HPP_INCLUDED

#  define BOOST_TR1_UTILITY_HPP_INCLUDED

#  include <boost/tr1/detail/config.hpp>

#ifdef BOOST_HAS_TR1_UTILITY

#  ifdef BOOST_HAS_INCLUDE_NEXT

#     include_next BOOST_TR1_HEADER(utility)

#  else

#     include BOOST_TR1_STD_HEADER(BOOST_TR1_PATH(utility))

#  endif

#else

#if defined(BOOST_TR1_USE_OLD_TUPLE)

#include <boost/type_traits/integral_constant.hpp>

#include <boost/type_traits/add_const.hpp>

#include <boost/type_traits/add_reference.hpp>

#include <boost/mpl/if.hpp>

namespace std{ namespace tr1{

template <class T> struct tuple_size; // forward declaration

template < int I, class T> struct tuple_element; // forward declaration

#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION

template <class T1, class T2>

struct tuple_size< ::std::pair<T1, T2> >

   : public ::boost::integral_constant< ::std::size_t, 2>

{

};

template <class T1, class T2>

struct tuple_element<0, ::std::pair<T1, T2> >

{

   typedef typename std::pair<T1, T2>::first_type type;

};

template <class T1, class T2>

struct tuple_element<1, std::pair<T1, T2> >

{

   typedef typename std::pair<T1, T2>::second_type type;

};

#endif

namespace tuple_detail{

   template <int I, class T1, class T2>

   struct tuple_get_result

   {

      typedef typename boost::mpl::if_c<I==0, T1, T2>::type t1;

      typedef typename boost::add_reference<t1>::type type;

   };

   template <int I, class T1, class T2>

   struct const_tuple_get_result

   {

      typedef typename boost::mpl::if_c<I==0, T1, T2>::type t1;

# if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT( 0x582))

      // I have absolutely no idea why add_const is not working here for Borland!

      // It passes all other free-standing tests, some strange interaction going on

      typedef typename boost::add_reference< const t1 >::type type;

# else

      typedef typename boost::add_const<t1>::type t2;

      typedef typename boost::add_reference<t2>::type type;

# endif

   };

template<int I, class T1, class T2>

inline typename tuple_detail::tuple_get_result<I,T1,T2>::type get(std::pair<T1, T2>& p, const ::boost::true_type&)

{

   return p.first;

}

template<int I, class T1, class T2>

inline typename tuple_detail::const_tuple_get_result<I,T1,T2>::type get(const std::pair<T1, T2>& p, const ::boost::true_type&)

{

   return p.first;

}

template<int I, class T1, class T2>

inline typename tuple_detail::tuple_get_result<I,T1,T2>::type get(std::pair<T1, T2>& p, const ::boost::false_type&)

{

   return p.second;

}

template<int I, class T1, class T2>

inline typename tuple_detail::const_tuple_get_result<I,T1,T2>::type get(const std::pair<T1, T2>& p, const ::boost::false_type&)

{

   return p.second;

}

}

template<int I, class T1, class T2> 

inline typename tuple_detail::tuple_get_result<I,T1,T2>::type get(std::pair<T1, T2>& p)

{

   return tuple_detail::get<I>(p, boost::integral_constant<bool, I==0>());

}

template<int I, class T1, class T2> 

inline typename tuple_detail::const_tuple_get_result<I,T1,T2>::type get(const std::pair<T1, T2>& p)

{

   return tuple_detail::get<I>(p, boost::integral_constant<bool, I==0>());

}

} } // namespaces

#else

#include <boost/tr1/tuple.hpp>

#endif

#endif

#endif