decltype.hpp

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            ////////////////////////////////////////////////////////////////////////////////////////////
            template<typename T>
            struct has_get_pointer
            {
                static T &t;
                BOOST_STATIC_CONSTANT(bool, value = sizeof(void *) == sizeof(get_pointer(t)));
                typedef mpl::bool_<value> type;
            };
        }

        using has_get_pointer_::has_get_pointer;
        
        ////////////////////////////////////////////////////////////////////////////////////////////
        namespace get_pointer_
        {
            using boost::get_pointer;

            template<typename T>
            typename disable_if<has_get_pointer<T>, T *>::type
            get_pointer(T &t)
            {
                return boost::addressof(t);
            }

            template<typename T>
            typename disable_if<has_get_pointer<T>, T const *>::type
            get_pointer(T const &t)
            {
                return boost::addressof(t);
            }
            
            ////////////////////////////////////////////////////////////////////////////////////////////
            template<
                typename T
              , typename U
              , bool IsMemPtr = is_member_object_pointer<
                    typename remove_reference<U>::type
                >::value
            >
            struct mem_ptr_fun
            {
                BOOST_PROTO_DECLTYPE_(
                    proto::detail::make_mutable<T>() ->* proto::detail::make<U>()
                  , result_type
                )

                result_type operator()(
                    typename add_reference<typename add_const<T>::type>::type t
                  , typename add_reference<typename add_const<U>::type>::type u
                ) const
                {
                    return t ->* u;
                }
            };

            ////////////////////////////////////////////////////////////////////////////////////////////
            template<typename T, typename U>
            struct mem_ptr_fun<T, U, true>
            {
                BOOST_PROTO_DECLTYPE_(
                    get_pointer(proto::detail::make_mutable<T>()) ->* proto::detail::make<U>()
                  , result_type
                )

                result_type operator()(
                    typename add_reference<typename add_const<T>::type>::type t
                  , typename add_reference<typename add_const<U>::type>::type u
                ) const
                {
                    return get_pointer(t) ->* u;
                }
            };
        }

        using get_pointer_::mem_ptr_fun;

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename A0, typename A1>
        struct comma_result
        {
            BOOST_PROTO_DECLTYPE_((proto::detail::make<A0>(), proto::detail::make<A1>()), type)
        };

        template<typename A0>
        struct comma_result<A0, void>
        {
            typedef void type;
        };

        template<typename A1>
        struct comma_result<void, A1>
        {
            typedef A1 type;
        };

        template<>
        struct comma_result<void, void>
        {
            typedef void type;
        };

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        struct result_of_member;
        
        template<typename T, typename U>
        struct result_of_member<T U::*>
        {
            typedef T type;
        };

        template<typename T, typename Void = void>
        struct result_of_
          : boost::result_of<T>
        {};
        
        template<typename T, typename U>
        struct result_of_<T(U), typename enable_if<is_member_object_pointer<T> >::type>
        {
            typedef
                typename result_of_member<T>::type
            type;
        };

        template<typename T, typename U>
        struct result_of_<T(U &), typename enable_if<is_member_object_pointer<T> >::type>
        {
            typedef
                typename add_reference<
                    typename result_of_member<T>::type
                >::type
            type;
        };

        template<typename T, typename U>
        struct result_of_<T(U const &), typename enable_if<is_member_object_pointer<T> >::type>
        {
            typedef
                typename add_reference<
                    typename add_const<
                        typename result_of_member<T>::type
                    >::type
                >::type
            type;
        };

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T, typename U = T>
        struct result_of_fixup
          : mpl::if_c<is_function<T>::value, T *, U>
        {};

        template<typename T, typename U>
        struct result_of_fixup<T &, U>
          : result_of_fixup<T, T>
        {};

        template<typename T, typename U>
        struct result_of_fixup<T const &, U>
          : result_of_fixup<T, T>
        {};

        template<typename T, typename U>
        struct result_of_fixup<T *, U>
          : result_of_fixup<T, U>
        {};

        template<typename R, typename T, typename U>
        struct result_of_fixup<R T::*, U>
        {
            typedef R T::*type;
        };

        template<typename T, typename U>
        struct result_of_fixup<T const, U>
          : result_of_fixup<T, U>
        {};

        //// Tests for result_of_fixup
        //struct bar {};
        //BOOST_MPL_ASSERT((is_same<bar,        result_of_fixup<bar>::type>));
        //BOOST_MPL_ASSERT((is_same<bar const,  result_of_fixup<bar const>::type>));
        //BOOST_MPL_ASSERT((is_same<bar,        result_of_fixup<bar &>::type>));
        //BOOST_MPL_ASSERT((is_same<bar const,  result_of_fixup<bar const &>::type>));
        //BOOST_MPL_ASSERT((is_same<void(*)(),  result_of_fixup<void(*)()>::type>));
        //BOOST_MPL_ASSERT((is_same<void(*)(),  result_of_fixup<void(* const)()>::type>));
        //BOOST_MPL_ASSERT((is_same<void(*)(),  result_of_fixup<void(* const &)()>::type>));
        //BOOST_MPL_ASSERT((is_same<void(*)(),  result_of_fixup<void(&)()>::type>));

        template<typename T, typename PMF>
        struct memfun
        {
            typedef typename remove_const<typename remove_reference<PMF>::type>::type pmf_type;
            typedef typename boost::result_of<pmf_type(T)>::type result_type;

            memfun(T t, PMF pmf)
              : obj(t)
              , pmf(pmf)
            {}

            result_type operator()() const
            {
                using namespace get_pointer_;
                return (get_pointer(obj) ->* pmf)();
            }

            #define M0(Z, N, DATA)                                                                  \
            template<BOOST_PP_ENUM_PARAMS_Z(Z, N, typename A)>                                      \
            result_type operator()(BOOST_PP_ENUM_BINARY_PARAMS_Z(Z, N, A, const &a)) const          \
            {                                                                                       \
                using namespace get_pointer_;                                                       \
                return (get_pointer(obj) ->* pmf)(BOOST_PP_ENUM_PARAMS_Z(Z, N, a));                  \
            }                                                                                       \
            /**/
            BOOST_PP_REPEAT_FROM_TO(1, BOOST_PROTO_MAX_ARITY, M0, ~)
            #undef M0

        private:
            T obj;
            PMF pmf;
        };

    } // namespace detail
}}

#endif