sfinae_errors.hpp

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/*
@Copyright Barrett Adair 2016-2017
 
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 
*/
 
#ifndef BOOST_CLBL_TRTS_SFINAE_ERRORS_HPP
#define BOOST_CLBL_TRTS_SFINAE_ERRORS_HPP
 
#include <boost/callable_traits/detail/config.hpp>
 
namespace boost { namespace callable_traits { namespace detail {
 
        struct sfinae_error{};
 
        template<typename T>
        struct success {
            static constexpr bool value = true;
            struct _ { using type = T; };
        };
    
        template<bool B, typename T>
        struct fail_if : T {
            static_assert(std::is_base_of<sfinae_error, T>::value,
                "incorrect usage of fail_if");
 
            static constexpr bool value = B;
        };
 
        template<typename T, typename... FailIfs>
        using sfinae_try = typename BOOST_CLBL_TRTS_DISJUNCTION(
                FailIfs..., success<T>)::_::type;
 
        template<typename FailMsg, typename ForceTwoPhaseLookup>
        struct fail {
            using type = typename std::conditional<std::is_same<ForceTwoPhaseLookup, std::false_type>::value,
            FailMsg, FailMsg>::type::_::type;
        };
 
}}} // namespace boost::callable_traits::detail
 
#define BOOST_CLBL_TRTS_PP_CAT_(x, y) x ## y
#define BOOST_CLBL_TRTS_PP_CAT(x, y) BOOST_CLBL_TRTS_PP_CAT_(x, y)
 
#define BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(origin) \
namespace error {                                          \
    template<typename ErrorMessage>                        \
    struct origin :                                        \
        ::boost::callable_traits::detail::sfinae_error     \
        { struct _ {}; };                                  \
}                                                          \
 
 
#define BOOST_CLBL_TRTS_SFINAE_MSG(origin, name) \
struct BOOST_CLBL_TRTS_PP_CAT(name, _ ){};       \
struct name : error::origin<                     \
    BOOST_CLBL_TRTS_PP_CAT(name, _ )>{};         \
 
 
namespace boost { namespace callable_traits {
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(parameters)
    BOOST_CLBL_TRTS_SFINAE_MSG(parameters, index_out_of_range_for_parameter_list)
    BOOST_CLBL_TRTS_SFINAE_MSG(parameters, cannot_determine_parameters_for_this_type)
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(varargs)
    BOOST_CLBL_TRTS_SFINAE_MSG(varargs, varargs_are_illegal_for_this_type)
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(member_qualifiers)
    BOOST_CLBL_TRTS_SFINAE_MSG(member_qualifiers, member_qualifiers_are_illegal_for_this_type)
    BOOST_CLBL_TRTS_SFINAE_MSG(member_qualifiers, this_compiler_doesnt_support_abominable_function_types)
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(transaction_safe_)
    BOOST_CLBL_TRTS_SFINAE_MSG(transaction_safe_, transaction_safe_is_not_supported_by_this_configuration)
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(expand_args)
    BOOST_CLBL_TRTS_SFINAE_MSG(expand_args, cannot_expand_the_parameter_list_of_first_template_argument)
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(member_pointer_required)
    BOOST_CLBL_TRTS_SFINAE_MSG(member_pointer_required, type_is_not_a_member_pointer)
 
    BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(reference_error)
    BOOST_CLBL_TRTS_SFINAE_MSG(reference_error, reference_type_not_supported_by_this_metafunction)
 
}} // namespace boost::callable_traits
 
#endif // #ifndef BOOST_CLBL_TRTS_SFINAE_ERRORS_HPP