projects / ceph.git / blame
| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | /*! |
| 2 | @file | |
| 3 | Defines `boost::hana::minus`. | |
| 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_MINUS_HPP | |
| 11 | #define BOOST_HANA_MINUS_HPP | |
| 12 | ||
| 13 | #include <boost/hana/fwd/minus.hpp> | |
| 14 | ||
| 15 | #include <boost/hana/concept/constant.hpp> | |
| 16 | #include <boost/hana/concept/group.hpp> | |
| 17 | #include <boost/hana/config.hpp> | |
| 18 | #include <boost/hana/core/common.hpp> | |
| 19 | #include <boost/hana/core/to.hpp> | |
| 20 | #include <boost/hana/core/dispatch.hpp> | |
| 21 | #include <boost/hana/detail/canonical_constant.hpp> | |
| 22 | #include <boost/hana/detail/has_common_embedding.hpp> | |
| 23 | #include <boost/hana/fwd/negate.hpp> | |
| 24 | #include <boost/hana/plus.hpp> | |
| 25 | #include <boost/hana/value.hpp> | |
| 26 | ||
| 27 | #include <type_traits> | |
| 28 | ||
| 29 | ||
| 30 | BOOST_HANA_NAMESPACE_BEGIN | |
| 31 | //! @cond | |
| 32 | template <typename X, typename Y> | |
| 33 | constexpr decltype(auto) minus_t::operator()(X&& x, Y&& y) const { | |
| 34 | using T = typename hana::tag_of<X>::type; | |
| 35 | using U = typename hana::tag_of<Y>::type; | |
| 36 | using Minus = BOOST_HANA_DISPATCH_IF(decltype(minus_impl<T, U>{}), | |
| 37 | hana::Group<T>::value && | |
| 38 | hana::Group<U>::value | |
| 39 | ); | |
| 40 | ||
| 41 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
| 42 | static_assert(hana::Group<T>::value, | |
| 43 | "hana::minus(x, y) requires 'x' to be in a Group"); | |
| 44 | ||
| 45 | static_assert(hana::Group<U>::value, | |
| 46 | "hana::minus(x, y) requires 'y' to be in a Group"); | |
| 47 | #endif | |
| 48 | ||
| 49 | return Minus::apply(static_cast<X&&>(x), static_cast<Y&&>(y)); | |
| 50 | } | |
| 51 | //! @endcond | |
| 52 | ||
| 53 | template <typename T, typename U, bool condition> | |
| 54 | struct minus_impl<T, U, when<condition>> : default_ { | |
| 55 | template <typename ...Args> | |
| 56 | static constexpr auto apply(Args&& ...) = delete; | |
| 57 | }; | |
| 58 | ||
| 59 | template <typename T, bool condition> | |
| 60 | struct minus_impl<T, T, when<condition>> : default_ { | |
| 61 | template <typename X, typename Y> | |
| 62 | static constexpr decltype(auto) apply(X&& x, Y&& y) { | |
| 63 | return hana::plus(static_cast<X&&>(x), | |
| 64 | hana::negate(static_cast<Y&&>(y))); | |
| 65 | } | |
| 66 | }; | |
| 67 | ||
| 68 | // Cross-type overload | |
| 69 | template <typename T, typename U> | |
| 70 | struct minus_impl<T, U, when< | |
| 71 | detail::has_nontrivial_common_embedding<Group, T, U>::value | |
| 72 | >> { | |
| 73 | using C = typename common<T, U>::type; | |
| 74 | template <typename X, typename Y> | |
| 75 | static constexpr decltype(auto) apply(X&& x, Y&& y) { | |
| 76 | return hana::minus(hana::to<C>(static_cast<X&&>(x)), | |
| 77 | hana::to<C>(static_cast<Y&&>(y))); | |
| 78 | } | |
| 79 | }; | |
| 80 | ||
| 81 | ////////////////////////////////////////////////////////////////////////// | |
| 82 | // Model for arithmetic data types | |
| 83 | ////////////////////////////////////////////////////////////////////////// | |
| 84 | template <typename T> | |
| 85 | struct minus_impl<T, T, when<std::is_arithmetic<T>::value && | |
| 86 | !std::is_same<bool, T>::value>> { | |
| 87 | template <typename X, typename Y> | |
| 88 | static constexpr decltype(auto) apply(X&& x, Y&& y) | |
| 89 | { return static_cast<X&&>(x) - static_cast<Y&&>(y); } | |
| 90 | }; | |
| 91 | ||
| 92 | ////////////////////////////////////////////////////////////////////////// | |
| 93 | // Model for Constants over a Group | |
| 94 | ////////////////////////////////////////////////////////////////////////// | |
| 95 | namespace detail { | |
| 96 | template <typename C, typename X, typename Y> | |
| 97 | struct constant_from_minus { | |
| 98 | static constexpr auto value = hana::minus(hana::value<X>(), hana::value<Y>()); | |
| 99 | using hana_tag = detail::CanonicalConstant<typename C::value_type>; | |
| 100 | }; | |
| 101 | } | |
| 102 | ||
| 103 | template <typename C> | |
| 104 | struct minus_impl<C, C, when< | |
| 105 | hana::Constant<C>::value && | |
| 106 | Group<typename C::value_type>::value | |
| 107 | >> { | |
| 108 | template <typename X, typename Y> | |
| 109 | static constexpr decltype(auto) apply(X const&, Y const&) | |
| 110 | { return hana::to<C>(detail::constant_from_minus<C, X, Y>{}); } | |
| 111 | }; | |
| 112 | BOOST_HANA_NAMESPACE_END | |
| 113 | ||
| 114 | #endif // !BOOST_HANA_MINUS_HPP |