ceph/src/boost/libs/hana/include/boost/hana/min.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::min`.
   4
   5 @copyright Louis Dionne 2013-2016
   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_MIN_HPP
  11 #define BOOST_HANA_MIN_HPP
  12
  13 #include <boost/hana/fwd/min.hpp>
  14
  15 #include <boost/hana/concept/orderable.hpp>
  16 #include <boost/hana/config.hpp>
  17 #include <boost/hana/core/dispatch.hpp>
  18 #include <boost/hana/if.hpp>
  19 #include <boost/hana/less.hpp>
  20
  21
  22 BOOST_HANA_NAMESPACE_BEGIN
  23     //! @cond
  24     template <typename X, typename Y>
  25     constexpr decltype(auto) min_t::operator()(X&& x, Y&& y) const {
  26         using T = typename hana::tag_of<X>::type;
  27         using U = typename hana::tag_of<Y>::type;
  28         using Min = BOOST_HANA_DISPATCH_IF(decltype(min_impl<T, U>{}),
  29             hana::Orderable<T>::value &&
  30             hana::Orderable<U>::value
  31         );
  32
  33     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  34         static_assert(hana::Orderable<T>::value,
  35         "hana::min(x, y) requires 'x' to be Orderable");
  36
  37         static_assert(hana::Orderable<U>::value,
  38         "hana::min(x, y) requires 'y' to be Orderable");
  39     #endif
  40
  41         return Min::apply(static_cast<X&&>(x), static_cast<Y&&>(y));
  42     }
  43     //! @endcond
  44
  45     template <typename T, typename U, bool condition>
  46     struct min_impl<T, U, when<condition>> : default_ {
  47         template <typename X, typename Y>
  48         static constexpr decltype(auto) apply(X&& x, Y&& y) {
  49             decltype(auto) cond = hana::less(x, y);
  50             return hana::if_(static_cast<decltype(cond)&&>(cond),
  51                 static_cast<X&&>(x),
  52                 static_cast<Y&&>(y)
  53             );
  54         }
  55     };
  56 BOOST_HANA_NAMESPACE_END
  57
  58 #endif // !BOOST_HANA_MIN_HPP