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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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