ceph/src/boost/libs/hana/test/_include/support/cnumeric.hpp

   1 // Copyright Louis Dionne 2013-2017
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   4
   5 #ifndef TEST_SUPPORT_CNUMERIC_HPP
   6 #define TEST_SUPPORT_CNUMERIC_HPP
   7
   8 #include <boost/hana/concept/integral_constant.hpp>
   9 #include <boost/hana/core/when.hpp>
  10 #include <boost/hana/fwd/core/to.hpp>
  11 #include <boost/hana/fwd/equal.hpp>
  12 #include <boost/hana/fwd/less.hpp>
  13
  14
  15 template <typename T>
  16 struct CNumeric { using value_type = T; };
  17
  18 template <typename T, T v>
  19 struct cnumeric_t {
  20     static constexpr T value = v;
  21     using hana_tag = CNumeric<T>;
  22     constexpr operator T() const { return value; }
  23 };
  24
  25 template <typename T, T v>
  26 constexpr cnumeric_t<T, v> cnumeric{};
  27
  28 template <typename T, T v>
  29 constexpr cnumeric_t<T, v> make_cnumeric() { return {}; }
  30
  31 namespace boost { namespace hana {
  32     // Constant and IntegralConstant
  33     template <typename T>
  34     struct IntegralConstant<CNumeric<T>> {
  35         static constexpr bool value = true;
  36     };
  37
  38     template <typename T, typename C>
  39     struct to_impl<CNumeric<T>, C, when<
  40         hana::IntegralConstant<C>::value
  41     >>
  42         : embedding<is_embedded<typename C::value_type, T>::value>
  43     {
  44         template <typename N>
  45         static constexpr auto apply(N const&)
  46         { return cnumeric<T, N::value>; }
  47     };
  48
  49     // Comparable
  50     template <typename T, typename U>
  51     struct equal_impl<CNumeric<T>, CNumeric<U>> {
  52         template <typename X, typename Y>
  53         static constexpr auto apply(X const&, Y const&)
  54         { return cnumeric<bool, X::value == Y::value>; }
  55     };
  56
  57     // Orderable
  58     template <typename T, typename U>
  59     struct less_impl<CNumeric<T>, CNumeric<U>> {
  60         template <typename X, typename Y>
  61         static constexpr auto apply(X const&, Y const&)
  62         { return cnumeric<bool, (X::value < Y::value)>; }
  63     };
  64 }} // end namespace boost::hana
  65
  66 #endif // !TEST_SUPPORT_CNUMERIC_HPP