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1 | /*! |
2 | @file | |
3 | Defines `boost::hana::hash`. | |
4 | ||
5 | @copyright Jason Rice 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_HASH_HPP | |
11 | #define BOOST_HANA_HASH_HPP | |
12 | ||
13 | #include <boost/hana/fwd/hash.hpp> | |
14 | ||
15 | #include <boost/hana/concept/hashable.hpp> | |
16 | #include <boost/hana/concept/integral_constant.hpp> | |
17 | #include <boost/hana/config.hpp> | |
18 | #include <boost/hana/core/dispatch.hpp> | |
19 | #include <boost/hana/fwd/integral_constant.hpp> | |
20 | #include <boost/hana/type.hpp> | |
21 | ||
22 | #include <type_traits> | |
23 | ||
24 | ||
1e59de90 | 25 | namespace boost { namespace hana { |
7c673cae FG |
26 | //! @cond |
27 | template <typename X> | |
28 | constexpr auto hash_t::operator()(X const& x) const { | |
29 | using Tag = typename hana::tag_of<X>::type; | |
30 | using Hash = BOOST_HANA_DISPATCH_IF(hash_impl<Tag>, | |
31 | hana::Hashable<Tag>::value | |
32 | ); | |
33 | ||
34 | #ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS | |
35 | static_assert(hana::Hashable<Tag>::value, | |
36 | "hana::hash(x) requires 'x' to be Hashable"); | |
37 | #endif | |
38 | ||
39 | return Hash::apply(x); | |
40 | } | |
41 | //! @endcond | |
42 | ||
43 | template <typename Tag, bool condition> | |
44 | struct hash_impl<Tag, when<condition>> : default_ { | |
45 | template <typename X> | |
46 | static constexpr auto apply(X const&) = delete; | |
47 | }; | |
48 | ||
49 | namespace detail { | |
50 | template <typename T, typename = void> | |
51 | struct hash_integral_helper; | |
52 | ||
53 | template <typename Member, typename T> | |
54 | struct hash_integral_helper<Member T::*> { | |
55 | template <typename X> | |
56 | static constexpr auto apply(X const&) { | |
57 | return hana::type_c<hana::integral_constant<Member T::*, X::value>>; | |
58 | } | |
59 | }; | |
60 | ||
61 | template <typename T> | |
62 | struct hash_integral_helper<T, | |
63 | typename std::enable_if<std::is_signed<T>::value>::type | |
64 | > { | |
65 | template <typename X> | |
66 | static constexpr auto apply(X const&) { | |
67 | constexpr signed long long x = X::value; | |
68 | return hana::type_c<hana::integral_constant<signed long long, x>>; | |
69 | } | |
70 | }; | |
71 | ||
72 | template <typename T> | |
73 | struct hash_integral_helper<T, | |
74 | typename std::enable_if<std::is_unsigned<T>::value>::type | |
75 | > { | |
76 | template <typename X> | |
77 | static constexpr auto apply(X const&) { | |
78 | constexpr unsigned long long x = X::value; | |
79 | return hana::type_c<hana::integral_constant<unsigned long long, x>>; | |
80 | } | |
81 | }; | |
82 | ||
83 | template <> | |
84 | struct hash_integral_helper<bool> { | |
85 | template <typename X> | |
86 | static constexpr auto apply(X const&) { | |
87 | return hana::type_c<hana::integral_constant<bool, X::value>>; | |
88 | } | |
89 | }; | |
90 | ||
91 | template <> | |
92 | struct hash_integral_helper<char> { | |
93 | template <typename X> | |
94 | static constexpr auto apply(X const&) { | |
95 | using T = std::conditional<std::is_signed<char>::value, | |
96 | signed long long, unsigned long long | |
97 | >::type; | |
98 | constexpr T x = X::value; | |
99 | return hana::type_c<hana::integral_constant<T, x>>; | |
100 | } | |
101 | }; | |
102 | } | |
103 | ||
104 | template <typename Tag> | |
105 | struct hash_impl<Tag, when<hana::IntegralConstant<Tag>::value>> { | |
106 | template <typename X> | |
107 | static constexpr auto apply(X const& x) { | |
108 | using T = typename std::remove_cv<decltype(X::value)>::type; | |
109 | return detail::hash_integral_helper<T>::apply(x); | |
110 | } | |
111 | }; | |
1e59de90 | 112 | }} // end namespace boost::hana |
7c673cae FG |
113 | |
114 | #endif // !BOOST_HANA_HASH_HPP |