Boost C++ Libraries

boost/phoenix/core/detail/phx2_result.hpp

/*=============================================================================
    Copyright (c) 2011 Thomas Heller

    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_PHOENIX_CORE_DETAIL_PHX2_RESULT_HPP
#define BOOST_PHOENIX_CORE_DETAIL_PHX2_RESULT_HPP
#include <boost/phoenix/core/limits.hpp>
#include <boost/phoenix/support/iterate.hpp>
#include <boost/mpl/has_xxx.hpp>
#include <boost/mpl/bool.hpp>

namespace boost { namespace phoenix {
    namespace detail
    {
        BOOST_MPL_HAS_XXX_TRAIT_DEF(result_type)

        template <typename Result>
        struct has_phx2_result_impl
        {
            typedef char yes;
            typedef char (&no)[2];

            template <typename A>
            static yes check_(typename A::type *);

            template <typename A>
            static no check_(...);

            static bool const value = (sizeof(yes) == sizeof(check_<Result>(0)));
            typedef boost::mpl::bool_<value> type;
        };

#ifdef BOOST_PHOENIX_NO_VARIADIC_PHX2_RESULT
        #include <boost/phoenix/core/detail/cpp03/phx2_result.hpp>
#else
        template <typename F, typename... A>
        struct has_phx2_result
            : mpl::eval_if<
                has_result_type<F>
              , mpl::false_
              , has_phx2_result_impl<typename F::template result<F(A...)> >
            >::type
        {};

        template <typename F, typename... A>
        struct phx2_result
        {
            typedef typename F::template result<A...>::type type;
        };

        template <typename F, typename... A>
        struct phx2_result<F, A &...>
        {
            typedef typename F::template result<A...>::type type;
        };

        template <typename F, typename... A>
        struct phx2_result<F, A const &...>
        {
            typedef typename F::template result<A...>::type type;
        };
#endif
    }
}}

#endif