1/*!
2@file
3Defines `boost::hana::not_`.
4
5Copyright Louis Dionne 2013-2022
6Distributed 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_NOT_HPP
11#define BOOST_HANA_NOT_HPP
12
13#include <boost/hana/fwd/not.hpp>
14
15#include <boost/hana/concept/constant.hpp>
16#include <boost/hana/concept/logical.hpp>
17#include <boost/hana/config.hpp>
18#include <boost/hana/core/to.hpp>
19#include <boost/hana/core/dispatch.hpp>
20#include <boost/hana/detail/canonical_constant.hpp>
21
22#include <type_traits>
23
24
25namespace boost { namespace hana {
26 //! @cond
27 template <typename X>
28 constexpr decltype(auto) not_t::operator()(X&& x) const {
29 using Bool = typename hana::tag_of<X>::type;
30 using Not = BOOST_HANA_DISPATCH_IF(hana::not_impl<Bool>,
31 hana::Logical<Bool>::value
32 );
33
34 #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
35 static_assert(hana::Logical<Bool>::value,
36 "hana::not_(cond) requires 'cond' to be a Logical");
37 #endif
38
39 return Not::apply(static_cast<X&&>(x));
40 }
41 //! @endcond
42
43 template <typename L, bool condition>
44 struct not_impl<L, when<condition>> : hana::default_ {
45 template <typename ...Args>
46 static constexpr auto apply(Args&& ...) = delete;
47 };
48
49 template <typename L>
50 struct not_impl<L, hana::when<std::is_arithmetic<L>::value>> {
51 template <typename Cond>
52 static constexpr Cond apply(Cond const& cond)
53 { return static_cast<Cond>(cond ? false : true); }
54 };
55
56 namespace detail {
57 template <typename C, typename X>
58 struct constant_from_not {
59 static constexpr auto value = hana::not_(hana::value<X>());
60 using hana_tag = detail::CanonicalConstant<typename C::value_type>;
61 };
62 }
63
64 template <typename C>
65 struct not_impl<C, hana::when<
66 hana::Constant<C>::value &&
67 hana::Logical<typename C::value_type>::value
68 >> {
69 template <typename Cond>
70 static constexpr auto apply(Cond const&)
71 { return hana::to<C>(detail::constant_from_not<C, Cond>{}); }
72 };
73}} // end namespace boost::hana
74
75#endif // !BOOST_HANA_NOT_HPP
76

source code of boost/libs/hana/include/boost/hana/not.hpp