ceph/src/boost/libs/hana/include/boost/hana/not.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::not_`.
   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_NOT_HPP
  11 #define BOOST_HANA_NOT_HPP
  12
  13 #include <boost/hana/fwd/not.hpp>
  14
  15 #include <boost/hana/concept/constant.hpp>
  16 #include <boost/hana/concept/logical.hpp>
  17 #include <boost/hana/config.hpp>
  18 #include <boost/hana/core/to.hpp>
  19 #include <boost/hana/core/dispatch.hpp>
  20 #include <boost/hana/detail/canonical_constant.hpp>
  21
  22 #include <type_traits>
  23
  24
  25 BOOST_HANA_NAMESPACE_BEGIN
  26     //! @cond
  27     template <typename X>
  28     constexpr decltype(auto) not_t::operator()(X&& x) const {
  29         using Bool = typename hana::tag_of<X>::type;
  30         using Not = BOOST_HANA_DISPATCH_IF(hana::not_impl<Bool>,
  31             hana::Logical<Bool>::value
  32         );
  33
  34     #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
  35         static_assert(hana::Logical<Bool>::value,
  36         "hana::not_(cond) requires 'cond' to be a Logical");
  37     #endif
  38
  39         return Not::apply(static_cast<X&&>(x));
  40     }
  41     //! @endcond
  42
  43     template <typename L, bool condition>
  44     struct not_impl<L, when<condition>> : hana::default_ {
  45         template <typename ...Args>
  46         static constexpr auto apply(Args&& ...) = delete;
  47     };
  48
  49     template <typename L>
  50     struct not_impl<L, hana::when<std::is_arithmetic<L>::value>> {
  51         template <typename Cond>
  52         static constexpr Cond apply(Cond const& cond)
  53         { return static_cast<Cond>(cond ? false : true); }
  54     };
  55
  56     namespace detail {
  57         template <typename C, typename X>
  58         struct constant_from_not {
  59             static constexpr auto value = hana::not_(hana::value<X>());
  60             using hana_tag = detail::CanonicalConstant<typename C::value_type>;
  61         };
  62     }
  63
  64     template <typename C>
  65     struct not_impl<C, hana::when<
  66         hana::Constant<C>::value &&
  67         hana::Logical<typename C::value_type>::value
  68     >> {
  69         template <typename Cond>
  70         static constexpr auto apply(Cond const&)
  71         { return hana::to<C>(detail::constant_from_not<C, Cond>{}); }
  72     };
  73 BOOST_HANA_NAMESPACE_END
  74
  75 #endif // !BOOST_HANA_NOT_HPP