projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | /*! |
| 2 | @file | |
| 3 | Defines `boost::hana::extend`. | |
| 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_EXTEND_HPP | |
| 11 | #define BOOST_HANA_EXTEND_HPP | |
| 12 | ||
| 13 | #include <boost/hana/fwd/extend.hpp> | |
| 14 | ||
| 15 | #include <boost/hana/concept/comonad.hpp> | |
| 16 | #include <boost/hana/config.hpp> | |
| 17 | #include <boost/hana/core/dispatch.hpp> | |
| 18 | #include <boost/hana/duplicate.hpp> | |
| 19 | #include <boost/hana/transform.hpp> | |
| 20 | ||
| 21 | ||
| 22 | BOOST_HANA_NAMESPACE_BEGIN | |
| 23 | //! @cond | |
| 24 | template <typename W_, typename F> | |
| 25 | constexpr decltype(auto) extend_t::operator()(W_&& w, F&& f) const { | |
| 26 | using W = typename hana::tag_of<W_>::type; | |
| 27 | using Extend = BOOST_HANA_DISPATCH_IF(extend_impl<W>, | |
| 28 | hana::Comonad<W>::value | |
| 29 | ); | |
| 30 | ||
| 31 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
| 32 | static_assert(hana::Comonad<W>::value, | |
| 33 | "hana::extend(w, f) requires 'w' to be a Comonad"); | |
| 34 | #endif | |
| 35 | ||
| 36 | return Extend::apply(static_cast<W_&&>(w), static_cast<F&&>(f)); | |
| 37 | } | |
| 38 | //! @endcond | |
| 39 | ||
| 40 | template <typename W, bool condition> | |
| 41 | struct extend_impl<W, when<condition>> : default_ { | |
| 42 | template <typename X, typename F> | |
| 43 | static constexpr decltype(auto) apply(X&& x, F&& f) { | |
| 44 | return hana::transform(hana::duplicate(static_cast<X&&>(x)), | |
| 45 | static_cast<F&&>(f)); | |
| 46 | } | |
| 47 | }; | |
| 48 | BOOST_HANA_NAMESPACE_END | |
| 49 | ||
| 50 | #endif // !BOOST_HANA_EXTEND_HPP |