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1 | /*! |
2 | @file | |
3 | Defines the `Logical` and `Comparable` models of `boost::hana::integral_constant`. | |
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_BOOL_HPP | |
11 | #define BOOST_HANA_BOOL_HPP | |
12 | ||
13 | #include <boost/hana/fwd/bool.hpp> | |
14 | ||
15 | #include <boost/hana/concept/integral_constant.hpp> | |
16 | #include <boost/hana/config.hpp> | |
17 | #include <boost/hana/core/to.hpp> | |
18 | #include <boost/hana/core/when.hpp> | |
19 | #include <boost/hana/detail/operators/arithmetic.hpp> | |
20 | #include <boost/hana/detail/operators/comparable.hpp> | |
21 | #include <boost/hana/detail/operators/logical.hpp> | |
22 | #include <boost/hana/detail/operators/orderable.hpp> | |
23 | #include <boost/hana/eval.hpp> | |
24 | #include <boost/hana/fwd/core/tag_of.hpp> | |
25 | #include <boost/hana/fwd/eval_if.hpp> | |
26 | #include <boost/hana/fwd/if.hpp> | |
27 | #include <boost/hana/fwd/value.hpp> | |
28 | ||
29 | #include <cstddef> | |
30 | #include <type_traits> | |
31 | #include <utility> | |
32 | ||
33 | ||
34 | BOOST_HANA_NAMESPACE_BEGIN | |
35 | ////////////////////////////////////////////////////////////////////////// | |
36 | // integral_constant | |
37 | ////////////////////////////////////////////////////////////////////////// | |
38 | //! @cond | |
39 | namespace ic_detail { | |
40 | template <typename T, T N, typename = std::make_integer_sequence<T, N>> | |
41 | struct go; | |
42 | ||
43 | template <typename T, T N, T ...i> | |
44 | struct go<T, N, std::integer_sequence<T, i...>> { | |
45 | using swallow = T[]; | |
46 | ||
47 | template <typename F> | |
48 | static constexpr void with_index(F&& f) | |
49 | { (void)swallow{T{}, ((void)f(integral_constant<T, i>{}), i)...}; } | |
50 | ||
51 | template <typename F> | |
52 | static constexpr void without_index(F&& f) | |
53 | { (void)swallow{T{}, ((void)f(), i)...}; } | |
54 | }; | |
55 | ||
56 | template <typename T, T v> | |
57 | template <typename F> | |
58 | constexpr void with_index_t<T, v>::operator()(F&& f) const | |
59 | { go<T, ((void)sizeof(&f), v)>::with_index(static_cast<F&&>(f)); } | |
60 | ||
61 | template <typename T, T v> | |
62 | template <typename F> | |
63 | constexpr void times_t<T, v>::operator()(F&& f) const | |
64 | { go<T, ((void)sizeof(&f), v)>::without_index(static_cast<F&&>(f)); } | |
65 | ||
66 | // avoid link-time error | |
67 | template <typename T, T v> | |
68 | constexpr with_index_t<T, v> times_t<T, v>::with_index; | |
69 | } | |
70 | ||
71 | // avoid link-time error | |
72 | template <typename T, T v> | |
73 | constexpr ic_detail::times_t<T, v> integral_constant<T, v>::times; | |
74 | ||
75 | template <typename T, T v> | |
76 | struct tag_of<integral_constant<T, v>> { | |
77 | using type = integral_constant_tag<T>; | |
78 | }; | |
79 | //! @endcond | |
80 | ||
81 | ////////////////////////////////////////////////////////////////////////// | |
82 | // Operators | |
83 | ////////////////////////////////////////////////////////////////////////// | |
84 | namespace detail { | |
85 | template <typename T> | |
86 | struct comparable_operators<integral_constant_tag<T>> { | |
87 | static constexpr bool value = true; | |
88 | }; | |
89 | template <typename T> | |
90 | struct orderable_operators<integral_constant_tag<T>> { | |
91 | static constexpr bool value = true; | |
92 | }; | |
93 | template <typename T> | |
94 | struct arithmetic_operators<integral_constant_tag<T>> { | |
95 | static constexpr bool value = true; | |
96 | }; | |
97 | template <typename T> | |
98 | struct logical_operators<integral_constant_tag<T>> { | |
99 | static constexpr bool value = true; | |
100 | }; | |
101 | } | |
102 | ||
103 | #define BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP(op) \ | |
104 | template <typename U, U u, typename V, V v> \ | |
105 | constexpr integral_constant<decltype(u op v), (u op v)> \ | |
106 | operator op(integral_constant<U, u>, integral_constant<V, v>) \ | |
107 | { return {}; } \ | |
108 | /**/ | |
109 | ||
110 | #define BOOST_HANA_INTEGRAL_CONSTANT_UNARY_OP(op) \ | |
111 | template <typename U, U u> \ | |
112 | constexpr integral_constant<decltype(op u), (op u)> \ | |
113 | operator op(integral_constant<U, u>) \ | |
114 | { return {}; } \ | |
115 | /**/ | |
116 | ||
117 | // Arithmetic | |
118 | BOOST_HANA_INTEGRAL_CONSTANT_UNARY_OP(+) | |
119 | ||
120 | // Bitwise | |
121 | BOOST_HANA_INTEGRAL_CONSTANT_UNARY_OP(~) | |
122 | BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP(&) | |
123 | BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP(|) | |
124 | BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP(^) | |
125 | BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP(<<) | |
126 | BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP(>>) | |
127 | ||
128 | #undef BOOST_HANA_INTEGRAL_CONSTANT_UNARY_OP | |
129 | #undef BOOST_HANA_INTEGRAL_CONSTANT_BINARY_OP | |
130 | ||
131 | ||
132 | ////////////////////////////////////////////////////////////////////////// | |
133 | // User-defined literal | |
134 | ////////////////////////////////////////////////////////////////////////// | |
135 | namespace ic_detail { | |
136 | ||
137 | constexpr int to_int(char c) { | |
138 | int result = 0; | |
139 | ||
140 | if (c >= 'A' && c <= 'F') { | |
141 | result = static_cast<int>(c) - static_cast<int>('A') + 10; | |
142 | } | |
143 | else if (c >= 'a' && c <= 'f') { | |
144 | result = static_cast<int>(c) - static_cast<int>('a') + 10; | |
145 | } | |
146 | else { | |
147 | result = static_cast<int>(c) - static_cast<int>('0'); | |
148 | } | |
149 | ||
150 | return result; | |
151 | } | |
152 | ||
153 | template<std::size_t N> | |
154 | constexpr long long parse(const char (&arr)[N]) { | |
155 | long long base = 10; | |
156 | std::size_t offset = 0; | |
157 | ||
158 | if (N > 2) { | |
159 | bool starts_with_zero = arr[0] == '0'; | |
160 | bool is_hex = starts_with_zero && arr[1] == 'x'; | |
161 | bool is_binary = starts_with_zero && arr[1] == 'b'; | |
162 | ||
163 | if (is_hex) { | |
164 | //0xDEADBEEF (hexadecimal) | |
165 | base = 16; | |
166 | offset = 2; | |
167 | } | |
168 | else if (is_binary) { | |
169 | //0b101011101 (binary) | |
170 | base = 2; | |
171 | offset = 2; | |
172 | } | |
173 | else if (starts_with_zero) { | |
174 | //012345 (octal) | |
175 | base = 8; | |
176 | offset = 1; | |
177 | } | |
178 | } | |
179 | ||
180 | long long number = 0; | |
181 | long long multiplier = 1; | |
182 | ||
183 | for (std::size_t i = 0; i < N - offset; ++i) { | |
184 | char c = arr[N - 1 - i]; | |
185 | number += to_int(c) * multiplier; | |
186 | multiplier *= base; | |
187 | } | |
188 | ||
189 | return number; | |
190 | } | |
191 | } | |
192 | ||
193 | namespace literals { | |
194 | template <char ...c> | |
195 | constexpr auto operator"" _c() { | |
196 | return hana::llong<ic_detail::parse<sizeof...(c)>({c...})>{}; | |
197 | } | |
198 | } | |
199 | ||
200 | ////////////////////////////////////////////////////////////////////////// | |
201 | // Model of Constant/IntegralConstant | |
202 | ////////////////////////////////////////////////////////////////////////// | |
203 | template <typename T> | |
204 | struct IntegralConstant<integral_constant_tag<T>> { | |
205 | static constexpr bool value = true; | |
206 | }; | |
207 | ||
208 | template <typename T, typename C> | |
209 | struct to_impl<integral_constant_tag<T>, C, when<hana::IntegralConstant<C>::value>> | |
210 | : embedding<is_embedded<typename C::value_type, T>::value> | |
211 | { | |
212 | template <typename N> | |
213 | static constexpr auto apply(N const&) | |
214 | { return integral_constant<T, N::value>{}; } | |
215 | }; | |
216 | ||
217 | ////////////////////////////////////////////////////////////////////////// | |
218 | // Optimizations | |
219 | ////////////////////////////////////////////////////////////////////////// | |
220 | template <typename T> | |
221 | struct eval_if_impl<integral_constant_tag<T>> { | |
222 | template <typename Cond, typename Then, typename Else> | |
223 | static constexpr decltype(auto) | |
224 | apply(Cond const&, Then&& t, Else&& e) { | |
225 | constexpr bool cond = static_cast<bool>(Cond::value); | |
226 | return eval_if_impl::apply(hana::bool_<cond>{}, | |
227 | static_cast<Then&&>(t), | |
228 | static_cast<Else&&>(e)); | |
229 | } | |
230 | ||
231 | template <typename Then, typename Else> | |
232 | static constexpr decltype(auto) | |
233 | apply(hana::true_ const&, Then&& t, Else&&) | |
234 | { return hana::eval(static_cast<Then&&>(t)); } | |
235 | ||
236 | template <typename Then, typename Else> | |
237 | static constexpr decltype(auto) | |
238 | apply(hana::false_ const&, Then&&, Else&& e) | |
239 | { return hana::eval(static_cast<Else&&>(e)); } | |
240 | }; | |
241 | ||
242 | template <typename T> | |
243 | struct if_impl<integral_constant_tag<T>> { | |
244 | template <typename Cond, typename Then, typename Else> | |
245 | static constexpr decltype(auto) | |
246 | apply(Cond const&, Then&& t, Else&& e) { | |
247 | constexpr bool cond = static_cast<bool>(Cond::value); | |
248 | return if_impl::apply(hana::bool_<cond>{}, | |
249 | static_cast<Then&&>(t), | |
250 | static_cast<Else&&>(e)); | |
251 | } | |
252 | ||
253 | //! @todo We could return `Then` instead of `auto` to sometimes save | |
254 | //! a copy, but that would break some code that would return a | |
255 | //! reference to a `type` object. I think the code that would be | |
256 | //! broken should be changed, but more thought needs to be given. | |
257 | template <typename Then, typename Else> | |
258 | static constexpr auto | |
259 | apply(hana::true_ const&, Then&& t, Else&&) | |
260 | { return static_cast<Then&&>(t); } | |
261 | ||
262 | template <typename Then, typename Else> | |
263 | static constexpr auto | |
264 | apply(hana::false_ const&, Then&&, Else&& e) | |
265 | { return static_cast<Else&&>(e); } | |
266 | }; | |
267 | BOOST_HANA_NAMESPACE_END | |
268 | ||
269 | #endif // !BOOST_HANA_BOOL_HPP |