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boost/proto/detail/decltype.hpp

///////////////////////////////////////////////////////////////////////////////
/// \file decltype.hpp
/// Contains definition the BOOST_PROTO_DECLTYPE_() macro and assorted helpers
//
//  Copyright 2008 Eric Niebler. 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_PROTO_DETAIL_DECLTYPE_HPP_EAN_04_04_2008
#define BOOST_PROTO_DETAIL_DECLTYPE_HPP_EAN_04_04_2008

#include <boost/proto/detail/prefix.hpp> // must be first include
#include <boost/config.hpp>
#include <boost/get_pointer.hpp>
#include <boost/preprocessor/cat.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
#include <boost/preprocessor/repetition/enum_binary_params.hpp>
#include <boost/preprocessor/repetition/repeat_from_to.hpp>
#include <boost/mpl/if.hpp>
#include <boost/type_traits/is_class.hpp>
#include <boost/type_traits/remove_cv.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/type_traits/is_pointer.hpp>
#include <boost/type_traits/is_function.hpp>
#include <boost/type_traits/is_member_object_pointer.hpp>
#include <boost/type_traits/add_const.hpp>
#include <boost/type_traits/add_reference.hpp>
#include <boost/typeof/typeof.hpp>
#include <boost/utility/addressof.hpp>
#include <boost/utility/result_of.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/proto/detail/suffix.hpp> // must be last include

// If we're generating doxygen documentation, hide all the nasty
// Boost.Typeof gunk.
#ifndef BOOST_PROTO_BUILDING_DOCS
# ifdef BOOST_HAS_DECLTYPE
#  define BOOST_PROTO_DECLTYPE_(EXPR, TYPE) typedef decltype(EXPR) TYPE;
# else
#  define BOOST_PROTO_DECLTYPE_NESTED_TYPEDEF_TPL_(NESTED, EXPR)                                    \
    BOOST_TYPEOF_NESTED_TYPEDEF_TPL(BOOST_PP_CAT(nested_and_hidden_, NESTED), EXPR)                 \
    static int const sz = sizeof(boost::proto::detail::check_reference(EXPR));                      \
    struct NESTED                                                                                   \
      : boost::mpl::if_c<                                                                           \
            1==sz                                                                                   \
          , typename BOOST_PP_CAT(nested_and_hidden_, NESTED)::type &                               \
          , typename BOOST_PP_CAT(nested_and_hidden_, NESTED)::type                                 \
        >                                                                                           \
    {};
#  define BOOST_PROTO_DECLTYPE_(EXPR, TYPE)                                                         \
    BOOST_PROTO_DECLTYPE_NESTED_TYPEDEF_TPL_(BOOST_PP_CAT(nested_, TYPE), (EXPR))                   \
    typedef typename BOOST_PP_CAT(nested_, TYPE)::type TYPE;
# endif
#else
/// INTERNAL ONLY
///
# define BOOST_PROTO_DECLTYPE_(EXPR, TYPE)                                                          \
    typedef detail::unspecified TYPE;
#endif

namespace boost { namespace proto
{
    namespace detail
    {
        namespace anyns
        {
            ////////////////////////////////////////////////////////////////////////////////////////////
            struct any
            {
                any(...);
                any operator=(any);
                any operator[](any);
                #define M0(Z, N, DATA) any operator()(BOOST_PP_ENUM_PARAMS_Z(Z, N, any BOOST_PP_INTERCEPT));
                BOOST_PP_REPEAT(BOOST_PROTO_MAX_ARITY, M0, ~)
                #undef M0

                template<typename T>
                operator T &() const volatile;

                any operator+();
                any operator-();
                any operator*();
                any operator&();
                any operator~();
                any operator!();
                any operator++();
                any operator--();
                any operator++(int);
                any operator--(int);

                friend any operator<<(any, any);
                friend any operator>>(any, any);
                friend any operator*(any, any);
                friend any operator/(any, any);
                friend any operator%(any, any);
                friend any operator+(any, any);
                friend any operator-(any, any);
                friend any operator<(any, any);
                friend any operator>(any, any);
                friend any operator<=(any, any);
                friend any operator>=(any, any);
                friend any operator==(any, any);
                friend any operator!=(any, any);
                friend any operator||(any, any);
                friend any operator&&(any, any);
                friend any operator&(any, any);
                friend any operator|(any, any);
                friend any operator^(any, any);
                friend any operator,(any, any);
                friend any operator->*(any, any);
                
                friend any operator<<=(any, any);
                friend any operator>>=(any, any);
                friend any operator*=(any, any);
                friend any operator/=(any, any);
                friend any operator%=(any, any);
                friend any operator+=(any, any);
                friend any operator-=(any, any);
                friend any operator&=(any, any);
                friend any operator|=(any, any);
                friend any operator^=(any, any);
            };
        }
        
        using anyns::any;
        
        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        struct as_mutable
        {
            typedef T &type;
        };

        template<typename T>
        struct as_mutable<T &>
        {
            typedef T &type;
        };

        template<typename T>
        struct as_mutable<T const &>
        {
            typedef T &type;
        };

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        T make();

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        typename as_mutable<T>::type make_mutable();

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        struct subscript_wrapper
          : T
        {
            using T::operator[];
            any operator[](any) const volatile;
        };

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        struct as_subscriptable
        {
            typedef
                typename mpl::if_c<
                    is_class<T>::value
                  , subscript_wrapper<T>
                  , T
                >::type
            type;
        };

        template<typename T>
        struct as_subscriptable<T const>
        {
            typedef
                typename mpl::if_c<
                    is_class<T>::value
                  , subscript_wrapper<T> const
                  , T const
                >::type
            type;
        };

        template<typename T>
        struct as_subscriptable<T &>
        {
            typedef
                typename mpl::if_c<
                    is_class<T>::value
                  , subscript_wrapper<T> &
                  , T &
                >::type
            type;
        };

        template<typename T>
        struct as_subscriptable<T const &>
        {
            typedef
                typename mpl::if_c<
                    is_class<T>::value
                  , subscript_wrapper<T> const &
                  , T const &
                >::type
            type;
        };

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        typename as_subscriptable<T>::type make_subscriptable();

        ////////////////////////////////////////////////////////////////////////////////////////////
        template<typename T>
        char check_reference(T &);

        template<typename T>
        char (&check_reference(T const &))[2];

        namespace has_get_pointer_
        {
            using boost::get_pointer;
            void *(&get_pointer(...))[2];

            ////////////////////////////////////////////////////////////////////////////////////////////
            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