callable_traits/detail/sfinae_errors.hpp

0001 /*
0002 @Copyright Barrett Adair 2016-2017
0003
0004 Distributed under the Boost Software License, Version 1.0.
0005 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
0006
0007 */
0008
0009 #ifndef BOOST_CLBL_TRTS_SFINAE_ERRORS_HPP
0010 #define BOOST_CLBL_TRTS_SFINAE_ERRORS_HPP
0011
0012 #include <boost/callable_traits/detail/config.hpp>
0013
0014 namespace boost { namespace callable_traits { namespace detail {
0015
0016         struct sfinae_error{};
0017
0018         template<typename T>
0019         struct success {
0020             static constexpr bool value = true;
0021             struct _ { using type = T; };
0022         };
0023
0024         template<bool B, typename T>
0025         struct fail_if : T {
0026             static_assert(std::is_base_of<sfinae_error, T>::value,
0027                 "incorrect usage of fail_if");
0028
0029             static constexpr bool value = B;
0030         };
0031
0032         template<typename T, typename... FailIfs>
0033         using sfinae_try = typename BOOST_CLBL_TRTS_DISJUNCTION(
0034                 FailIfs..., success<T>)::_::type;
0035
0036         template<typename FailMsg, typename ForceTwoPhaseLookup>
0037         struct fail {
0038             using type = typename std::conditional<std::is_same<ForceTwoPhaseLookup, std::false_type>::value,
0039             FailMsg, FailMsg>::type::_::type;
0040         };
0041
0042 }}} // namespace boost::callable_traits::detail
0043
0044 #define BOOST_CLBL_TRTS_PP_CAT_(x, y) x ## y
0045 #define BOOST_CLBL_TRTS_PP_CAT(x, y) BOOST_CLBL_TRTS_PP_CAT_(x, y)
0046
0047 #define BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(origin) \
0048 namespace error {                                          \
0049     template<typename ErrorMessage>                        \
0050     struct origin :                                        \
0051         ::boost::callable_traits::detail::sfinae_error     \
0052         { struct _ {}; };                                  \
0053 }                                                          \
0054 /**/
0055
0056 #define BOOST_CLBL_TRTS_SFINAE_MSG(origin, name) \
0057 struct BOOST_CLBL_TRTS_PP_CAT(name, _ ){};       \
0058 struct name : error::origin<                     \
0059     BOOST_CLBL_TRTS_PP_CAT(name, _ )>{};         \
0060 /**/
0061
0062 namespace boost { namespace callable_traits {
0063
0064     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(parameters)
0065     BOOST_CLBL_TRTS_SFINAE_MSG(parameters, index_out_of_range_for_parameter_list)
0066     BOOST_CLBL_TRTS_SFINAE_MSG(parameters, cannot_determine_parameters_for_this_type)
0067
0068     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(varargs)
0069     BOOST_CLBL_TRTS_SFINAE_MSG(varargs, varargs_are_illegal_for_this_type)
0070
0071     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(member_qualifiers)
0072     BOOST_CLBL_TRTS_SFINAE_MSG(member_qualifiers, member_qualifiers_are_illegal_for_this_type)
0073     BOOST_CLBL_TRTS_SFINAE_MSG(member_qualifiers, this_compiler_doesnt_support_abominable_function_types)
0074
0075     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(transaction_safe_)
0076     BOOST_CLBL_TRTS_SFINAE_MSG(transaction_safe_, transaction_safe_is_not_supported_by_this_configuration)
0077
0078     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(expand_args)
0079     BOOST_CLBL_TRTS_SFINAE_MSG(expand_args, cannot_expand_the_parameter_list_of_first_template_argument)
0080
0081     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(member_pointer_required)
0082     BOOST_CLBL_TRTS_SFINAE_MSG(member_pointer_required, type_is_not_a_member_pointer)
0083
0084     BOOST_CLBL_TRTS_DEFINE_SFINAE_ERROR_ORIGIN(reference_error)
0085     BOOST_CLBL_TRTS_SFINAE_MSG(reference_error, reference_type_not_supported_by_this_metafunction)
0086
0087 }} // namespace boost::callable_traits
0088
0089 #endif // #ifndef BOOST_CLBL_TRTS_SFINAE_ERRORS_HPP