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 #ifdef BOOST_PFR_HAS_STD_MODULE
0013 import std;
0014 #else
0015 #include <functional>
0016 #include <type_traits>
0017 #endif
0018
0019 namespace boost { namespace pfr { namespace detail {
0020 ///////////////////// `value` is true if Detector<Tleft, Tright> does not compile (SFINAE)
0021     struct can_not_apply{};
0022
0023     template <template <class, class> class Detector, class Tleft, class Tright>
0024     struct not_appliable {
0025         static constexpr bool value = std::is_same<
0026             Detector<Tleft, Tright>,
0027             can_not_apply
0028         >::value;
0029     };
0030
0031 ///////////////////// Detectors for different operators
0032     template <class S, class T> auto comp_eq_detector_msvc_helper(long) -> decltype(std::declval<S>() == std::declval<T>());
0033     template <class S, class T> can_not_apply comp_eq_detector_msvc_helper(int);
0034     template <class T1, class T2> using comp_eq_detector = decltype(comp_eq_detector_msvc_helper<T1,T2>(1L));
0035
0036     template <class S, class T> auto comp_ne_detector_msvc_helper(long) -> decltype(std::declval<S>() != std::declval<T>());
0037     template <class S, class T> can_not_apply comp_ne_detector_msvc_helper(int);
0038     template <class T1, class T2> using comp_ne_detector = decltype(comp_ne_detector_msvc_helper<T1,T2>(1L));
0039
0040     template <class S, class T> auto comp_lt_detector_msvc_helper(long) -> decltype(std::declval<S>() < std::declval<T>());
0041     template <class S, class T> can_not_apply comp_lt_detector_msvc_helper(int);
0042     template <class T1, class T2> using comp_lt_detector = decltype(comp_lt_detector_msvc_helper<T1,T2>(1L));
0043
0044     template <class S, class T> auto comp_le_detector_msvc_helper(long) -> decltype(std::declval<S>() <= std::declval<T>());
0045     template <class S, class T> can_not_apply comp_le_detector_msvc_helper(int);
0046     template <class T1, class T2> using comp_le_detector = decltype(comp_le_detector_msvc_helper<T1,T2>(1L));
0047
0048     template <class S, class T> auto comp_gt_detector_msvc_helper(long) -> decltype(std::declval<S>() > std::declval<T>());
0049     template <class S, class T> can_not_apply comp_gt_detector_msvc_helper(int);
0050     template <class T1, class T2> using comp_gt_detector = decltype(comp_gt_detector_msvc_helper<T1,T2>(1L));
0051
0052     template <class S, class T> auto comp_ge_detector_msvc_helper(long) -> decltype(std::declval<S>() >= std::declval<T>());
0053     template <class S, class T> can_not_apply comp_ge_detector_msvc_helper(int);
0054     template <class T1, class T2> using comp_ge_detector = decltype(comp_ge_detector_msvc_helper<T1,T2>(1L));
0055
0056
0057     template <class S> auto hash_detector_msvc_helper(long) -> decltype(std::hash<S>{}(std::declval<S>()));
0058     template <class S> can_not_apply hash_detector_msvc_helper(int);
0059     template <class T1, class T2> using hash_detector = decltype(hash_detector_msvc_helper<T1,T2>(1L));
0060
0061
0062     template <class S, class T> auto ostreamable_detector_msvc_helper(long) -> decltype(std::declval<S>() << std::declval<T>());
0063     template <class S, class T> can_not_apply ostreamable_detector_msvc_helper(int);
0064     template <class S, class T> using ostreamable_detector = decltype(ostreamable_detector_msvc_helper<S,T>(1L));
0065
0066     template <class S, class T> auto istreamable_detector_msvc_helper(long) -> decltype(std::declval<S>() >> std::declval<T>());
0067     template <class S, class T> can_not_apply istreamable_detector_msvc_helper(int);
0068     template <class S, class T> using istreamable_detector = decltype(istreamable_detector_msvc_helper<S,T>(1L));
0069
0070 }}} // namespace boost::pfr::detail
0071
0072 #endif // BOOST_PFR_DETAIL_DETECTORS_HPP
0073
0074