projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | /*! |
| 2 | @file | |
| 3 | Forward declares `boost::hana::not_`. | |
| 4 | ||
| 5 | @copyright Louis Dionne 2013-2016 | |
| 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_FWD_NOT_HPP | |
| 11 | #define BOOST_HANA_FWD_NOT_HPP | |
| 12 | ||
| 13 | #include <boost/hana/config.hpp> | |
| 14 | #include <boost/hana/core/when.hpp> | |
| 15 | ||
| 16 | ||
| 17 | BOOST_HANA_NAMESPACE_BEGIN | |
| 18 | //! Negates a `Logical`. | |
| 19 | //! @ingroup group-Logical | |
| 20 | //! | |
| 21 | //! This method returns a `Logical` with the same tag, but whose | |
| 22 | //! truth-value is negated. Specifically, `not_(x)` returns a false-valued | |
| 23 | //! `Logical` if `x` is a true-valued `Logical`, and a true-valued one | |
| 24 | //! otherwise. | |
| 25 | //! | |
| 26 | //! | |
| 27 | //! Example | |
| 28 | //! ------- | |
| 29 | //! @include example/not.cpp | |
| 30 | #ifdef BOOST_HANA_DOXYGEN_INVOKED | |
| 31 | constexpr auto not_ = [](auto&& x) -> decltype(auto) { | |
| 32 | return tag-dispatched; | |
| 33 | }; | |
| 34 | #else | |
| 35 | template <typename L, typename = void> | |
| 36 | struct not_impl : not_impl<L, when<true>> { }; | |
| 37 | ||
| 38 | struct not_t { | |
| 39 | template <typename X> | |
| 40 | constexpr decltype(auto) operator()(X&& x) const; | |
| 41 | }; | |
| 42 | ||
| 43 | constexpr not_t not_{}; | |
| 44 | #endif | |
| 45 | BOOST_HANA_NAMESPACE_END | |
| 46 | ||
| 47 | #endif // !BOOST_HANA_FWD_NOT_HPP |