ceph/src/boost/boost/hana/less_equal.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::less_equal`.
   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_LESS_EQUAL_HPP
  11 #define BOOST_HANA_LESS_EQUAL_HPP
  12
  13 #include <boost/hana/fwd/less_equal.hpp>
  14
  15 #include <boost/hana/concept/orderable.hpp>
  16 #include <boost/hana/config.hpp>
  17 #include <boost/hana/core/common.hpp>
  18 #include <boost/hana/core/to.hpp>
  19 #include <boost/hana/core/dispatch.hpp>
  20 #include <boost/hana/detail/has_common_embedding.hpp>
  21 #include <boost/hana/detail/nested_than.hpp> // required by fwd decl
  22 #include <boost/hana/less.hpp>
  23 #include <boost/hana/not.hpp>
  24
  25 #include <type_traits>
  26
  27
  28 BOOST_HANA_NAMESPACE_BEGIN
  29     //! @cond
  30     template <typename X, typename Y>
  31     constexpr auto less_equal_t::operator()(X&& x, Y&& y) const {
  32         using T = typename hana::tag_of<X>::type;
  33         using U = typename hana::tag_of<Y>::type;
  34         using LessEqual = BOOST_HANA_DISPATCH_IF(
  35             decltype(less_equal_impl<T, U>{}),
  36             hana::Orderable<T>::value &&
  37             hana::Orderable<U>::value
  38         );
  39
  40     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  41         static_assert(hana::Orderable<T>::value,
  42         "hana::less_equal(x, y) requires 'x' to be Orderable");
  43
  44         static_assert(hana::Orderable<U>::value,
  45         "hana::less_equal(x, y) requires 'y' to be Orderable");
  46     #endif
  47
  48         return LessEqual::apply(static_cast<X&&>(x), static_cast<Y&&>(y));
  49     }
  50     //! @endcond
  51
  52     template <typename T, typename U, bool condition>
  53     struct less_equal_impl<T, U, when<condition>> : default_ {
  54         template <typename X, typename Y>
  55         static constexpr decltype(auto) apply(X&& x, Y&& y) {
  56             return hana::not_(hana::less(static_cast<Y&&>(y),
  57                                          static_cast<X&&>(x)));
  58         }
  59     };
  60
  61     // Cross-type overload
  62     template <typename T, typename U>
  63     struct less_equal_impl<T, U, when<
  64         detail::has_nontrivial_common_embedding<Orderable, T, U>::value
  65     >> {
  66         using C = typename hana::common<T, U>::type;
  67         template <typename X, typename Y>
  68         static constexpr decltype(auto) apply(X&& x, Y&& y) {
  69             return hana::less_equal(hana::to<C>(static_cast<X&&>(x)),
  70                                     hana::to<C>(static_cast<Y&&>(y)));
  71         }
  72     };
  73 BOOST_HANA_NAMESPACE_END
  74
  75 #endif // !BOOST_HANA_LESS_EQUAL_HPP