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- /*!
- @file
- Defines `boost::hana::not_`.
- @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_NOT_HPP
- #define BOOST_HANA_NOT_HPP
- #include <boost/hana/fwd/not.hpp>
- #include <boost/hana/concept/constant.hpp>
- #include <boost/hana/concept/logical.hpp>
- #include <boost/hana/config.hpp>
- #include <boost/hana/core/to.hpp>
- #include <boost/hana/core/dispatch.hpp>
- #include <boost/hana/detail/canonical_constant.hpp>
- #include <type_traits>
- BOOST_HANA_NAMESPACE_BEGIN
- //! @cond
- template <typename X>
- constexpr decltype(auto) not_t::operator()(X&& x) const {
- using Bool = typename hana::tag_of<X>::type;
- using Not = BOOST_HANA_DISPATCH_IF(hana::not_impl<Bool>,
- hana::Logical<Bool>::value
- );
- #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
- static_assert(hana::Logical<Bool>::value,
- "hana::not_(cond) requires 'cond' to be a Logical");
- #endif
- return Not::apply(static_cast<X&&>(x));
- }
- //! @endcond
- template <typename L, bool condition>
- struct not_impl<L, when<condition>> : hana::default_ {
- template <typename ...Args>
- static constexpr auto apply(Args&& ...) = delete;
- };
- template <typename L>
- struct not_impl<L, hana::when<std::is_arithmetic<L>::value>> {
- template <typename Cond>
- static constexpr Cond apply(Cond const& cond)
- { return static_cast<Cond>(cond ? false : true); }
- };
- namespace detail {
- template <typename C, typename X>
- struct constant_from_not {
- static constexpr auto value = hana::not_(hana::value<X>());
- using hana_tag = detail::CanonicalConstant<typename C::value_type>;
- };
- }
- template <typename C>
- struct not_impl<C, hana::when<
- hana::Constant<C>::value &&
- hana::Logical<typename C::value_type>::value
- >> {
- template <typename Cond>
- static constexpr auto apply(Cond const&)
- { return hana::to<C>(detail::constant_from_not<C, Cond>{}); }
- };
- BOOST_HANA_NAMESPACE_END
- #endif // !BOOST_HANA_NOT_HPP
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