// Copyright David Abrahams 2006. 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)

#ifndef BOOST_CONCEPT_REQUIRES_DWA2006430_HPP

# define BOOST_CONCEPT_REQUIRES_DWA2006430_HPP

# include <boost/config.hpp>

# include <boost/parameter/aux_/parenthesized_type.hpp>

# include <boost/concept/assert.hpp>

# include <boost/preprocessor/seq/for_each.hpp>

namespace boost { 

// Template for use in handwritten assertions

template <class Model, class More>

struct requires_ : More

{

# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)

    typedef typename More::type type;

# endif 

    BOOST_CONCEPT_ASSERT((Model));

};

// Template for use by macros, where models must be wrapped in parens.

// This isn't in namespace detail to keep extra cruft out of resulting

// error messages.

template <class ModelFn>

struct _requires_

{

    enum { value = 0 };

    BOOST_CONCEPT_ASSERT_FN(ModelFn);

};

template <int check, class Result>

struct Requires_ : ::boost::parameter::aux::unaryfunptr_arg_type<Result>

{

# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)

    typedef typename ::boost::parameter::aux::unaryfunptr_arg_type<Result>::type type;

# endif 

};

# if BOOST_WORKAROUND(BOOST_INTEL_WIN, BOOST_TESTED_AT(1010))

#  define BOOST_CONCEPT_REQUIRES_(r,data,t) | (::boost::_requires_<void(*)t>::value)

# else 

#  define BOOST_CONCEPT_REQUIRES_(r,data,t) + (::boost::_requires_<void(*)t>::value)

# endif

#if defined(NDEBUG) || BOOST_WORKAROUND(BOOST_MSVC, < 1300)

# define BOOST_CONCEPT_REQUIRES(models, result)                                    \

    typename ::boost::parameter::aux::unaryfunptr_arg_type<void(*)result>::type

#elif BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))

// Same thing as below without the initial typename

# define BOOST_CONCEPT_REQUIRES(models, result)                                \

    ::boost::Requires_<                                                        \

      (0 BOOST_PP_SEQ_FOR_EACH(BOOST_CONCEPT_REQUIRES_, ~, models)),           \

      ::boost::parameter::aux::unaryfunptr_arg_type<void(*)result>          \

                     >::type

#else

// This just ICEs on MSVC6 :(

# define BOOST_CONCEPT_REQUIRES(models, result)                                        \

    typename ::boost::Requires_<                                                       \

      (0 BOOST_PP_SEQ_FOR_EACH(BOOST_CONCEPT_REQUIRES_, ~, models)),                   \

      void(*)result                                                                 \

    >::type

#endif 

// C++0x proposed syntax changed.  This supports an older usage

#define BOOST_CONCEPT_WHERE(models,result) BOOST_CONCEPT_REQUIRES(models,result)

} // namespace boost::concept_check

#endif // BOOST_CONCEPT_REQUIRES_DWA2006430_HPP