ceph/src/boost/boost/hana/detail/concepts.hpp

   1 /*!
   2 @file
   3 Defines concepts from the Standard library.
   4
   5 @copyright Louis Dionne 2013-2017
   6 Distributed 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
  20 BOOST_HANA_NAMESPACE_BEGIN 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 } BOOST_HANA_NAMESPACE_END
  77
  78 #endif // !BOOST_HANA_DETAIL_CONCEPTS_HPP