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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::is_subset`. | |
4 | ||
b32b8144 | 5 | @copyright Louis Dionne 2013-2017 |
7c673cae FG |
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_IS_SUBSET_HPP | |
11 | #define BOOST_HANA_IS_SUBSET_HPP | |
12 | ||
13 | #include <boost/hana/fwd/is_subset.hpp> | |
14 | ||
15 | #include <boost/hana/all_of.hpp> | |
16 | #include <boost/hana/concept/searchable.hpp> | |
17 | #include <boost/hana/config.hpp> | |
18 | #include <boost/hana/contains.hpp> | |
19 | #include <boost/hana/core/common.hpp> | |
20 | #include <boost/hana/core/to.hpp> | |
21 | #include <boost/hana/core/dispatch.hpp> | |
22 | #include <boost/hana/detail/has_common_embedding.hpp> | |
23 | #include <boost/hana/functional/partial.hpp> | |
24 | ||
25 | ||
1e59de90 | 26 | namespace boost { namespace hana { |
7c673cae FG |
27 | //! @cond |
28 | template <typename Xs, typename Ys> | |
29 | constexpr auto is_subset_t::operator()(Xs&& xs, Ys&& ys) const { | |
30 | using S1 = typename hana::tag_of<Xs>::type; | |
31 | using S2 = typename hana::tag_of<Ys>::type; | |
32 | using IsSubset = BOOST_HANA_DISPATCH_IF( | |
33 | decltype(is_subset_impl<S1, S2>{}), | |
34 | hana::Searchable<S1>::value && | |
35 | hana::Searchable<S2>::value && | |
36 | !is_default<is_subset_impl<S1, S2>>::value | |
37 | ); | |
38 | ||
39 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
40 | static_assert(hana::Searchable<S1>::value, | |
41 | "hana::is_subset(xs, ys) requires 'xs' to be Searchable"); | |
42 | ||
43 | static_assert(hana::Searchable<S2>::value, | |
44 | "hana::is_subset(xs, ys) requires 'ys' to be Searchable"); | |
45 | ||
46 | static_assert(!is_default<is_subset_impl<S1, S2>>::value, | |
47 | "hana::is_subset(xs, ys) requires 'xs' and 'ys' to be embeddable " | |
48 | "in a common Searchable"); | |
49 | #endif | |
50 | ||
51 | return IsSubset::apply(static_cast<Xs&&>(xs), static_cast<Ys&&>(ys)); | |
52 | } | |
53 | //! @endcond | |
54 | ||
55 | template <typename S1, typename S2, bool condition> | |
56 | struct is_subset_impl<S1, S2, when<condition>> : default_ { | |
57 | template <typename ...Args> | |
58 | static constexpr auto apply(Args&& ...) = delete; | |
59 | }; | |
60 | ||
61 | template <typename S, bool condition> | |
62 | struct is_subset_impl<S, S, when<condition>> { | |
63 | template <typename Xs, typename Ys> | |
64 | static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) { | |
65 | return hana::all_of(static_cast<Xs&&>(xs), | |
66 | hana::partial(hana::contains, static_cast<Ys&&>(ys))); | |
67 | } | |
68 | }; | |
69 | ||
70 | // Cross-type overload | |
71 | template <typename S1, typename S2> | |
72 | struct is_subset_impl<S1, S2, when< | |
73 | detail::has_nontrivial_common_embedding<Searchable, S1, S2>::value | |
74 | >> { | |
75 | using C = typename common<S1, S2>::type; | |
76 | template <typename Xs, typename Ys> | |
77 | static constexpr decltype(auto) apply(Xs&& xs, Ys&& ys) { | |
78 | return hana::is_subset(hana::to<C>(static_cast<Xs&&>(xs)), | |
79 | hana::to<C>(static_cast<Ys&&>(ys))); | |
80 | } | |
81 | }; | |
1e59de90 | 82 | }} // end namespace boost::hana |
7c673cae FG |
83 | |
84 | #endif // !BOOST_HANA_IS_SUBSET_HPP |