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- /*!
- @file
- Defines `boost::hana::Constant`.
- @copyright Louis Dionne 2013-2017
- Distributed under the Boost Software License, Version 1.0.
- (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
- */
- #ifndef BOOST_HANA_CONCEPT_CONSTANT_HPP
- #define BOOST_HANA_CONCEPT_CONSTANT_HPP
- #include <boost/hana/fwd/concept/constant.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/default.hpp>
- #include <boost/hana/core/tag_of.hpp>
- #include <boost/hana/detail/integral_constant.hpp>
- #include <boost/hana/value.hpp>
- BOOST_HANA_NAMESPACE_BEGIN
- template <typename C>
- struct Constant
- : hana::integral_constant<bool,
- !is_default<value_impl<typename tag_of<C>::type>>::value
- >
- { };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_CONCEPT_CONSTANT_HPP
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