ceph/src/boost/libs/hana/include/boost/hana/concept/constant.hpp

   1 /*!
   2 @file
   3 Defines `boost::hana::Constant`.
   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_CONCEPT_CONSTANT_HPP
  11 #define BOOST_HANA_CONCEPT_CONSTANT_HPP
  12
  13 #include <boost/hana/fwd/concept/constant.hpp>
  14
  15 #include <boost/hana/config.hpp>
  16 #include <boost/hana/core/default.hpp>
  17 #include <boost/hana/core/tag_of.hpp>
  18 #include <boost/hana/value.hpp>
  19
  20
  21 BOOST_HANA_NAMESPACE_BEGIN
  22     template <typename C>
  23     struct Constant {
  24         using Tag = typename tag_of<C>::type;
  25         static constexpr bool value = !is_default<value_impl<Tag>>::value;
  26     };
  27 BOOST_HANA_NAMESPACE_END
  28
  29 #endif // !BOOST_HANA_CONCEPT_CONSTANT_HPP