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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::find`. | |
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_FIND_HPP | |
11 | #define BOOST_HANA_FIND_HPP | |
12 | ||
13 | #include <boost/hana/fwd/find.hpp> | |
14 | ||
15 | #include <boost/hana/concept/searchable.hpp> | |
16 | #include <boost/hana/config.hpp> | |
17 | #include <boost/hana/core/dispatch.hpp> | |
18 | #include <boost/hana/equal.hpp> | |
19 | #include <boost/hana/find_if.hpp> | |
20 | ||
21 | ||
22 | BOOST_HANA_NAMESPACE_BEGIN | |
23 | //! @cond | |
24 | template <typename Xs, typename Key> | |
25 | constexpr auto find_t::operator()(Xs&& xs, Key const& key) const { | |
26 | using S = typename hana::tag_of<Xs>::type; | |
27 | using Find = BOOST_HANA_DISPATCH_IF(find_impl<S>, | |
28 | hana::Searchable<S>::value | |
29 | ); | |
30 | ||
31 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
32 | static_assert(hana::Searchable<S>::value, | |
33 | "hana::find(xs, key) requires 'xs' to be Searchable"); | |
34 | #endif | |
35 | ||
36 | return Find::apply(static_cast<Xs&&>(xs), key); | |
37 | } | |
38 | //! @endcond | |
39 | ||
40 | namespace detail { | |
41 | template <typename T> | |
42 | struct equal_to { | |
43 | T const& t; | |
44 | template <typename U> | |
45 | constexpr auto operator()(U const& u) const { | |
46 | return hana::equal(t, u); | |
47 | } | |
48 | }; | |
49 | } | |
50 | ||
51 | template <typename S, bool condition> | |
52 | struct find_impl<S, when<condition>> : default_ { | |
53 | template <typename Xs, typename Key> | |
54 | static constexpr auto apply(Xs&& xs, Key const& key) { | |
55 | return hana::find_if(static_cast<Xs&&>(xs), | |
56 | detail::equal_to<Key>{key}); | |
57 | } | |
58 | }; | |
59 | BOOST_HANA_NAMESPACE_END | |
60 | ||
61 | #endif // !BOOST_HANA_FIND_HPP |