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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::greater_equal`. | |
4 | ||
b32b8144 | 5 | @copyright Louis Dionne 2013-2017 |
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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_GREATER_EQUAL_HPP | |
11 | #define BOOST_HANA_GREATER_EQUAL_HPP | |
12 | ||
13 | #include <boost/hana/fwd/greater_equal.hpp> | |
14 | ||
15 | #include <boost/hana/concept/orderable.hpp> | |
16 | #include <boost/hana/config.hpp> | |
17 | #include <boost/hana/core/common.hpp> | |
18 | #include <boost/hana/core/to.hpp> | |
19 | #include <boost/hana/core/dispatch.hpp> | |
20 | #include <boost/hana/detail/concepts.hpp> | |
21 | #include <boost/hana/detail/has_common_embedding.hpp> | |
22 | #include <boost/hana/detail/nested_than.hpp> // required by fwd decl | |
23 | #include <boost/hana/if.hpp> | |
24 | #include <boost/hana/not.hpp> | |
25 | ||
26 | ||
1e59de90 | 27 | namespace boost { namespace hana { |
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28 | //! @cond |
29 | template <typename X, typename Y> | |
30 | constexpr decltype(auto) greater_equal_t::operator()(X&& x, Y&& y) const { | |
31 | using T = typename hana::tag_of<X>::type; | |
32 | using U = typename hana::tag_of<Y>::type; | |
33 | using GreaterEqual = BOOST_HANA_DISPATCH_IF( | |
34 | decltype(greater_equal_impl<T, U>{}), | |
35 | hana::Orderable<T>::value && | |
36 | hana::Orderable<U>::value | |
37 | ); | |
38 | ||
39 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
40 | static_assert(hana::Orderable<T>::value, | |
41 | "hana::greater_equal(x, y) requires 'x' to be Orderable"); | |
42 | ||
43 | static_assert(hana::Orderable<U>::value, | |
44 | "hana::greater_equal(x, y) requires 'y' to be Orderable"); | |
45 | #endif | |
46 | ||
47 | return GreaterEqual::apply(static_cast<X&&>(x), static_cast<Y&&>(y)); | |
48 | } | |
49 | //! @endcond | |
50 | ||
51 | template <typename T, typename U, bool condition> | |
52 | struct greater_equal_impl<T, U, when<condition>> : default_ { | |
53 | template <typename X, typename Y> | |
54 | static constexpr decltype(auto) apply(X x, Y y) { | |
55 | return hana::not_(hana::less(static_cast<X&&>(x), | |
56 | static_cast<Y&&>(y))); | |
57 | } | |
58 | }; | |
59 | ||
60 | // Cross-type overload | |
61 | template <typename T, typename U> | |
62 | struct greater_equal_impl<T, U, when< | |
63 | detail::has_nontrivial_common_embedding<Orderable, T, U>::value | |
64 | >> { | |
65 | using C = typename hana::common<T, U>::type; | |
66 | template <typename X, typename Y> | |
67 | static constexpr decltype(auto) apply(X&& x, Y&& y) { | |
68 | return hana::greater_equal(hana::to<C>(static_cast<X&&>(x)), | |
69 | hana::to<C>(static_cast<Y&&>(y))); | |
70 | } | |
71 | }; | |
1e59de90 | 72 | }} // end namespace boost::hana |
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73 | |
74 | #endif // !BOOST_HANA_GREATER_EQUAL_HPP |