1/*!
2@file
3Defines concepts from the Standard library.
4
5Copyright Louis Dionne 2013-2022
6Distributed under the Boost Software License, Version 1.0.
7(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
8 */
9
10#ifndef BOOST_HANA_DETAIL_CONCEPTS_HPP
11#define BOOST_HANA_DETAIL_CONCEPTS_HPP
12
13#include <boost/hana/config.hpp>
14#include <boost/hana/detail/std_common_type.hpp>
15#include <boost/hana/detail/void_t.hpp>
16
17#include <type_traits>
18
19
20namespace boost { namespace hana { namespace detail {
21 //! @cond
22 //////////////////////////////////////////////////////////////////////////
23 // EqualityComparable
24 //////////////////////////////////////////////////////////////////////////
25 template <typename T, typename U = T, typename = void>
26 struct EqualityComparable : std::false_type { };
27
28 template <typename T>
29 struct EqualityComparable<T, T, detail::void_t<
30 decltype(static_cast<T&&>(*(T*)0) == static_cast<T&&>(*(T*)0) ? 0:0),
31 decltype(static_cast<T&&>(*(T*)0) != static_cast<T&&>(*(T*)0) ? 0:0)
32 >> : std::true_type { };
33
34 template <typename T, typename U>
35 struct EqualityComparable<T, U, typename std::enable_if<
36 !std::is_same<T, U>::value, detail::void_t<
37 decltype(static_cast<T&&>(*(T*)0) == static_cast<U&&>(*(U*)0) ? 0:0),
38 decltype(static_cast<U&&>(*(U*)0) == static_cast<T&&>(*(T*)0) ? 0:0),
39 decltype(static_cast<T&&>(*(T*)0) != static_cast<U&&>(*(U*)0) ? 0:0),
40 decltype(static_cast<U&&>(*(U*)0) != static_cast<T&&>(*(T*)0) ? 0:0),
41 typename detail::std_common_type<T, U>::type
42 >>::type> : std::integral_constant<bool,
43 EqualityComparable<T>::value &&
44 EqualityComparable<U>::value &&
45 EqualityComparable<typename detail::std_common_type<T, U>::type>::value
46 > { };
47
48
49 //////////////////////////////////////////////////////////////////////////
50 // LessThanComparable
51 //////////////////////////////////////////////////////////////////////////
52 template <typename T, typename U = T, typename = void>
53 struct LessThanComparable : std::false_type { };
54
55 template <typename T>
56 struct LessThanComparable<T, T, detail::void_t<
57 decltype(static_cast<T&&>(*(T*)0) < static_cast<T&&>(*(T*)0) ? 0:0)
58 >> : std::true_type { };
59
60 template <typename T, typename U>
61 struct LessThanComparable<T, U, std::enable_if_t<
62 !std::is_same<T, U>::value,
63 detail::void_t<
64 decltype(static_cast<T&&>(*(T*)0) < static_cast<U&&>(*(U*)0) ? 0:0),
65 decltype(static_cast<U&&>(*(U*)0) < static_cast<T&&>(*(T*)0) ? 0:0),
66 typename detail::std_common_type<T, U>::type
67 >
68 >>
69 : std::integral_constant<bool,
70 LessThanComparable<T>::value &&
71 LessThanComparable<U>::value &&
72 LessThanComparable<typename detail::std_common_type<T, U>::type>::value
73 >
74 { };
75 //! @endcond
76} }} // end namespace boost::hana
77
78#endif // !BOOST_HANA_DETAIL_CONCEPTS_HPP
79

source code of boost/libs/hana/include/boost/hana/detail/concepts.hpp