projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | /*! |
| 2 | @file | |
| 3 | Defines `boost::hana::lift`. | |
| 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_LIFT_HPP | |
| 11 | #define BOOST_HANA_LIFT_HPP | |
| 12 | ||
| 13 | #include <boost/hana/fwd/lift.hpp> | |
| 14 | ||
| 15 | #include <boost/hana/concept/applicative.hpp> | |
| 16 | #include <boost/hana/concept/sequence.hpp> | |
| 17 | #include <boost/hana/config.hpp> | |
| 18 | #include <boost/hana/core/dispatch.hpp> | |
| 19 | #include <boost/hana/core/make.hpp> | |
| 20 | ||
| 21 | ||
| 22 | BOOST_HANA_NAMESPACE_BEGIN | |
| 23 | template <typename A> | |
| 24 | struct lift_t { | |
| 25 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
| 26 | static_assert(hana::Applicative<A>::value, | |
| 27 | "hana::lift<A> requires 'A' to be an Applicative"); | |
| 28 | #endif | |
| 29 | ||
| 30 | template <typename X> | |
| 31 | constexpr auto operator()(X&& x) const { | |
| 32 | using Lift = BOOST_HANA_DISPATCH_IF(lift_impl<A>, | |
| 33 | hana::Applicative<A>::value | |
| 34 | ); | |
| 35 | ||
| 36 | return Lift::apply(static_cast<X&&>(x)); | |
| 37 | } | |
| 38 | }; | |
| 39 | ||
| 40 | template <typename A, bool condition> | |
| 41 | struct lift_impl<A, when<condition>> : default_ { | |
| 42 | template <typename ...Args> | |
| 43 | static constexpr auto apply(Args&& ...args) = delete; | |
| 44 | }; | |
| 45 | ||
| 46 | template <typename S> | |
| 47 | struct lift_impl<S, when<Sequence<S>::value>> { | |
| 48 | template <typename X> | |
| 49 | static constexpr decltype(auto) apply(X&& x) | |
| 50 | { return hana::make<S>(static_cast<X&&>(x)); } | |
| 51 | }; | |
| 52 | BOOST_HANA_NAMESPACE_END | |
| 53 | ||
| 54 | #endif // !BOOST_HANA_LIFT_HPP |