1 // Components for compile-time parsing of numbers -*- C++ -*-
2
3 // Copyright (C) 2013-2023 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24
25 /** @file bits/parse_numbers.h
26 * This is an internal header file, included by other library headers.
27 * Do not attempt to use it directly. @headername{chrono}
28 */
29
30 #ifndef _GLIBCXX_PARSE_NUMBERS_H
31 #define _GLIBCXX_PARSE_NUMBERS_H 1
32
33 #pragma GCC system_header
34
35 // From n3642.pdf except I added binary literals and digit separator '\''.
36
37 #if __cplusplus >= 201402L
38
39 #include <type_traits>
40 #include <ext/numeric_traits.h>
41
42 namespace std _GLIBCXX_VISIBILITY(default)
43 {
44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45
46 namespace __parse_int
47 {
48 template<unsigned _Base, char _Dig>
49 struct _Digit;
50
51 template<unsigned _Base>
52 struct _Digit<_Base, '0'> : integral_constant<unsigned, 0>
53 {
54 using __valid = true_type;
55 };
56
57 template<unsigned _Base>
58 struct _Digit<_Base, '1'> : integral_constant<unsigned, 1>
59 {
60 using __valid = true_type;
61 };
62
63 template<unsigned _Base, unsigned _Val>
64 struct _Digit_impl : integral_constant<unsigned, _Val>
65 {
66 static_assert(_Base > _Val, "invalid digit");
67 using __valid = true_type;
68 };
69
70 template<unsigned _Base>
71 struct _Digit<_Base, '2'> : _Digit_impl<_Base, 2>
72 { };
73
74 template<unsigned _Base>
75 struct _Digit<_Base, '3'> : _Digit_impl<_Base, 3>
76 { };
77
78 template<unsigned _Base>
79 struct _Digit<_Base, '4'> : _Digit_impl<_Base, 4>
80 { };
81
82 template<unsigned _Base>
83 struct _Digit<_Base, '5'> : _Digit_impl<_Base, 5>
84 { };
85
86 template<unsigned _Base>
87 struct _Digit<_Base, '6'> : _Digit_impl<_Base, 6>
88 { };
89
90 template<unsigned _Base>
91 struct _Digit<_Base, '7'> : _Digit_impl<_Base, 7>
92 { };
93
94 template<unsigned _Base>
95 struct _Digit<_Base, '8'> : _Digit_impl<_Base, 8>
96 { };
97
98 template<unsigned _Base>
99 struct _Digit<_Base, '9'> : _Digit_impl<_Base, 9>
100 { };
101
102 template<unsigned _Base>
103 struct _Digit<_Base, 'a'> : _Digit_impl<_Base, 0xa>
104 { };
105
106 template<unsigned _Base>
107 struct _Digit<_Base, 'A'> : _Digit_impl<_Base, 0xa>
108 { };
109
110 template<unsigned _Base>
111 struct _Digit<_Base, 'b'> : _Digit_impl<_Base, 0xb>
112 { };
113
114 template<unsigned _Base>
115 struct _Digit<_Base, 'B'> : _Digit_impl<_Base, 0xb>
116 { };
117
118 template<unsigned _Base>
119 struct _Digit<_Base, 'c'> : _Digit_impl<_Base, 0xc>
120 { };
121
122 template<unsigned _Base>
123 struct _Digit<_Base, 'C'> : _Digit_impl<_Base, 0xc>
124 { };
125
126 template<unsigned _Base>
127 struct _Digit<_Base, 'd'> : _Digit_impl<_Base, 0xd>
128 { };
129
130 template<unsigned _Base>
131 struct _Digit<_Base, 'D'> : _Digit_impl<_Base, 0xd>
132 { };
133
134 template<unsigned _Base>
135 struct _Digit<_Base, 'e'> : _Digit_impl<_Base, 0xe>
136 { };
137
138 template<unsigned _Base>
139 struct _Digit<_Base, 'E'> : _Digit_impl<_Base, 0xe>
140 { };
141
142 template<unsigned _Base>
143 struct _Digit<_Base, 'f'> : _Digit_impl<_Base, 0xf>
144 { };
145
146 template<unsigned _Base>
147 struct _Digit<_Base, 'F'> : _Digit_impl<_Base, 0xf>
148 { };
149
150 // Digit separator
151 template<unsigned _Base>
152 struct _Digit<_Base, '\''> : integral_constant<unsigned, 0>
153 {
154 using __valid = false_type;
155 };
156
157 //------------------------------------------------------------------------------
158
159 template<unsigned long long _Val>
160 using __ull_constant = integral_constant<unsigned long long, _Val>;
161
162 template<unsigned _Base, char _Dig, char... _Digs>
163 struct _Power_help
164 {
165 using __next = typename _Power_help<_Base, _Digs...>::type;
166 using __valid_digit = typename _Digit<_Base, _Dig>::__valid;
167 using type
168 = __ull_constant<__next::value * (__valid_digit{} ? _Base : 1ULL)>;
169 };
170
171 template<unsigned _Base, char _Dig>
172 struct _Power_help<_Base, _Dig>
173 {
174 using __valid_digit = typename _Digit<_Base, _Dig>::__valid;
175 using type = __ull_constant<__valid_digit::value>;
176 };
177
178 template<unsigned _Base, char... _Digs>
179 struct _Power : _Power_help<_Base, _Digs...>::type
180 { };
181
182 template<unsigned _Base>
183 struct _Power<_Base> : __ull_constant<0>
184 { };
185
186 //------------------------------------------------------------------------------
187
188 template<unsigned _Base, unsigned long long _Pow, char _Dig, char... _Digs>
189 struct _Number_help
190 {
191 using __digit = _Digit<_Base, _Dig>;
192 using __valid_digit = typename __digit::__valid;
193 using __next = _Number_help<_Base,
194 __valid_digit::value ? _Pow / _Base : _Pow,
195 _Digs...>;
196 using type = __ull_constant<_Pow * __digit::value + __next::type::value>;
197 static_assert((type::value / _Pow) == __digit::value,
198 "integer literal does not fit in unsigned long long");
199 };
200
201 // Skip past digit separators:
202 template<unsigned _Base, unsigned long long _Pow, char _Dig, char..._Digs>
203 struct _Number_help<_Base, _Pow, '\'', _Dig, _Digs...>
204 : _Number_help<_Base, _Pow, _Dig, _Digs...>
205 { };
206
207 // Terminating case for recursion:
208 template<unsigned _Base, char _Dig>
209 struct _Number_help<_Base, 1ULL, _Dig>
210 {
211 using type = __ull_constant<_Digit<_Base, _Dig>::value>;
212 };
213
214 template<unsigned _Base, char... _Digs>
215 struct _Number
216 : _Number_help<_Base, _Power<_Base, _Digs...>::value, _Digs...>::type
217 { };
218
219 template<unsigned _Base>
220 struct _Number<_Base>
221 : __ull_constant<0>
222 { };
223
224 //------------------------------------------------------------------------------
225
226 template<char... _Digs>
227 struct _Parse_int;
228
229 template<char... _Digs>
230 struct _Parse_int<'0', 'b', _Digs...>
231 : _Number<2U, _Digs...>::type
232 { };
233
234 template<char... _Digs>
235 struct _Parse_int<'0', 'B', _Digs...>
236 : _Number<2U, _Digs...>::type
237 { };
238
239 template<char... _Digs>
240 struct _Parse_int<'0', 'x', _Digs...>
241 : _Number<16U, _Digs...>::type
242 { };
243
244 template<char... _Digs>
245 struct _Parse_int<'0', 'X', _Digs...>
246 : _Number<16U, _Digs...>::type
247 { };
248
249 template<char... _Digs>
250 struct _Parse_int<'0', _Digs...>
251 : _Number<8U, _Digs...>::type
252 { };
253
254 template<char... _Digs>
255 struct _Parse_int
256 : _Number<10U, _Digs...>::type
257 { };
258
259 } // namespace __parse_int
260
261
262 namespace __select_int
263 {
264 template<unsigned long long _Val, typename... _Ints>
265 struct _Select_int_base;
266
267 template<unsigned long long _Val, typename _IntType, typename... _Ints>
268 struct _Select_int_base<_Val, _IntType, _Ints...>
269 : __conditional_t<(_Val <= __gnu_cxx::__int_traits<_IntType>::__max),
270 integral_constant<_IntType, (_IntType)_Val>,
271 _Select_int_base<_Val, _Ints...>>
272 { };
273
274 template<unsigned long long _Val>
275 struct _Select_int_base<_Val>
276 { };
277
278 template<char... _Digs>
279 using _Select_int = typename _Select_int_base<
280 __parse_int::_Parse_int<_Digs...>::value,
281 unsigned char,
282 unsigned short,
283 unsigned int,
284 unsigned long,
285 unsigned long long
286 >::type;
287
288 } // namespace __select_int
289
290 _GLIBCXX_END_NAMESPACE_VERSION
291 } // namespace std
292
293 #endif // C++14
294
295 #endif // _GLIBCXX_PARSE_NUMBERS_H