| 1 | /*! |
|---|---|
| 2 | @file |
| 3 | Defines `boost::hana::Constant`. |
| 4 | |
| 5 | Copyright Louis Dionne 2013-2022 |
| 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/detail/integral_constant.hpp> |
| 19 | #include <boost/hana/value.hpp> |
| 20 | |
| 21 | |
| 22 | namespace boost { namespace hana { |
| 23 | template <typename C> |
| 24 | struct Constant |
| 25 | : hana::integral_constant<bool, |
| 26 | !is_default<value_impl<typename tag_of<C>::type>>::value |
| 27 | > |
| 28 | { }; |
| 29 | }} // end namespace boost::hana |
| 30 | |
| 31 | #endif // !BOOST_HANA_CONCEPT_CONSTANT_HPP |
| 32 |