pfr/detail/detectors.hpp

0001 // Copyright (c) 2016-2025 Antony Polukhin
0002 //
0003 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0004 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #ifndef BOOST_PFR_DETAIL_DETECTORS_HPP
0007 #define BOOST_PFR_DETAIL_DETECTORS_HPP
0008 #pragma once
0009
0010 #include <boost/pfr/detail/config.hpp>
0011
0012 #if !defined(BOOST_PFR_INTERFACE_UNIT)
0013 #include <functional>
0014 #include <type_traits>
0015 #endif
0016
0017 namespace boost { namespace pfr { namespace detail {
0018 ///////////////////// `value` is true if Detector<Tleft, Tright> does not compile (SFINAE)
0019     struct can_not_apply{};
0020
0021     template <template <class, class> class Detector, class Tleft, class Tright>
0022     struct not_applicable {
0023         static constexpr bool value = std::is_same<
0024             Detector<Tleft, Tright>,
0025             can_not_apply
0026         >::value;
0027     };
0028
0029 ///////////////////// Detectors for different operators
0030     template <class S, class T> auto comp_eq_detector_msvc_helper(long) -> decltype(std::declval<S>() == std::declval<T>());
0031     template <class S, class T> can_not_apply comp_eq_detector_msvc_helper(int);
0032     template <class T1, class T2> using comp_eq_detector = decltype(comp_eq_detector_msvc_helper<T1,T2>(1L));
0033
0034     template <class S, class T> auto comp_ne_detector_msvc_helper(long) -> decltype(std::declval<S>() != std::declval<T>());
0035     template <class S, class T> can_not_apply comp_ne_detector_msvc_helper(int);
0036     template <class T1, class T2> using comp_ne_detector = decltype(comp_ne_detector_msvc_helper<T1,T2>(1L));
0037
0038     template <class S, class T> auto comp_lt_detector_msvc_helper(long) -> decltype(std::declval<S>() < std::declval<T>());
0039     template <class S, class T> can_not_apply comp_lt_detector_msvc_helper(int);
0040     template <class T1, class T2> using comp_lt_detector = decltype(comp_lt_detector_msvc_helper<T1,T2>(1L));
0041
0042     template <class S, class T> auto comp_le_detector_msvc_helper(long) -> decltype(std::declval<S>() <= std::declval<T>());
0043     template <class S, class T> can_not_apply comp_le_detector_msvc_helper(int);
0044     template <class T1, class T2> using comp_le_detector = decltype(comp_le_detector_msvc_helper<T1,T2>(1L));
0045
0046     template <class S, class T> auto comp_gt_detector_msvc_helper(long) -> decltype(std::declval<S>() > std::declval<T>());
0047     template <class S, class T> can_not_apply comp_gt_detector_msvc_helper(int);
0048     template <class T1, class T2> using comp_gt_detector = decltype(comp_gt_detector_msvc_helper<T1,T2>(1L));
0049
0050     template <class S, class T> auto comp_ge_detector_msvc_helper(long) -> decltype(std::declval<S>() >= std::declval<T>());
0051     template <class S, class T> can_not_apply comp_ge_detector_msvc_helper(int);
0052     template <class T1, class T2> using comp_ge_detector = decltype(comp_ge_detector_msvc_helper<T1,T2>(1L));
0053
0054
0055     template <class S> auto hash_detector_msvc_helper(long) -> decltype(std::hash<S>{}(std::declval<S>()));
0056     template <class S> can_not_apply hash_detector_msvc_helper(int);
0057     template <class T1, class T2> using hash_detector = decltype(hash_detector_msvc_helper<T1,T2>(1L));
0058
0059
0060     template <class S, class T> auto ostreamable_detector_msvc_helper(long) -> decltype(std::declval<S>() << std::declval<T>());
0061     template <class S, class T> can_not_apply ostreamable_detector_msvc_helper(int);
0062     template <class S, class T> using ostreamable_detector = decltype(ostreamable_detector_msvc_helper<S,T>(1L));
0063
0064     template <class S, class T> auto istreamable_detector_msvc_helper(long) -> decltype(std::declval<S>() >> std::declval<T>());
0065     template <class S, class T> can_not_apply istreamable_detector_msvc_helper(int);
0066     template <class S, class T> using istreamable_detector = decltype(istreamable_detector_msvc_helper<S,T>(1L));
0067
0068 }}} // namespace boost::pfr::detail
0069
0070 #endif // BOOST_PFR_DETAIL_DETECTORS_HPP
0071
0072