1 // Components for compile-time parsing of numbers -*- C++ -*-
2
3 // Copyright (C) 2013-2019 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 > 201103L
38
39 #include <limits>
40
_GLIBCXX_VISIBILITY(default)41 namespace std _GLIBCXX_VISIBILITY(default)
42 {
43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
44
45 namespace __parse_int
46 {
47 template<unsigned _Base, char _Dig>
48 struct _Digit;
49
50 template<unsigned _Base>
51 struct _Digit<_Base, '0'> : integral_constant<unsigned, 0>
52 {
53 using __valid = true_type;
54 };
55
56 template<unsigned _Base>
57 struct _Digit<_Base, '1'> : integral_constant<unsigned, 1>
58 {
59 using __valid = true_type;
60 };
61
62 template<unsigned _Base, unsigned _Val>
63 struct _Digit_impl : integral_constant<unsigned, _Val>
64 {
65 static_assert(_Base > _Val, "invalid digit");
66 using __valid = true_type;
67 };
68
69 template<unsigned _Base>
70 struct _Digit<_Base, '2'> : _Digit_impl<_Base, 2>
71 { };
72
73 template<unsigned _Base>
74 struct _Digit<_Base, '3'> : _Digit_impl<_Base, 3>
75 { };
76
77 template<unsigned _Base>
78 struct _Digit<_Base, '4'> : _Digit_impl<_Base, 4>
79 { };
80
81 template<unsigned _Base>
82 struct _Digit<_Base, '5'> : _Digit_impl<_Base, 5>
83 { };
84
85 template<unsigned _Base>
86 struct _Digit<_Base, '6'> : _Digit_impl<_Base, 6>
87 { };
88
89 template<unsigned _Base>
90 struct _Digit<_Base, '7'> : _Digit_impl<_Base, 7>
91 { };
92
93 template<unsigned _Base>
94 struct _Digit<_Base, '8'> : _Digit_impl<_Base, 8>
95 { };
96
97 template<unsigned _Base>
98 struct _Digit<_Base, '9'> : _Digit_impl<_Base, 9>
99 { };
100
101 template<unsigned _Base>
102 struct _Digit<_Base, 'a'> : _Digit_impl<_Base, 0xa>
103 { };
104
105 template<unsigned _Base>
106 struct _Digit<_Base, 'A'> : _Digit_impl<_Base, 0xa>
107 { };
108
109 template<unsigned _Base>
110 struct _Digit<_Base, 'b'> : _Digit_impl<_Base, 0xb>
111 { };
112
113 template<unsigned _Base>
114 struct _Digit<_Base, 'B'> : _Digit_impl<_Base, 0xb>
115 { };
116
117 template<unsigned _Base>
118 struct _Digit<_Base, 'c'> : _Digit_impl<_Base, 0xc>
119 { };
120
121 template<unsigned _Base>
122 struct _Digit<_Base, 'C'> : _Digit_impl<_Base, 0xc>
123 { };
124
125 template<unsigned _Base>
126 struct _Digit<_Base, 'd'> : _Digit_impl<_Base, 0xd>
127 { };
128
129 template<unsigned _Base>
130 struct _Digit<_Base, 'D'> : _Digit_impl<_Base, 0xd>
131 { };
132
133 template<unsigned _Base>
134 struct _Digit<_Base, 'e'> : _Digit_impl<_Base, 0xe>
135 { };
136
137 template<unsigned _Base>
138 struct _Digit<_Base, 'E'> : _Digit_impl<_Base, 0xe>
139 { };
140
141 template<unsigned _Base>
142 struct _Digit<_Base, 'f'> : _Digit_impl<_Base, 0xf>
143 { };
144
145 template<unsigned _Base>
146 struct _Digit<_Base, 'F'> : _Digit_impl<_Base, 0xf>
147 { };
148
149 // Digit separator
150 template<unsigned _Base>
151 struct _Digit<_Base, '\''> : integral_constant<unsigned, 0>
152 {
153 using __valid = false_type;
154 };
155
156 //------------------------------------------------------------------------------
157
158 template<unsigned long long _Val>
159 using __ull_constant = integral_constant<unsigned long long, _Val>;
160
161 template<unsigned _Base, char _Dig, char... _Digs>
162 struct _Power_help
163 {
164 using __next = typename _Power_help<_Base, _Digs...>::type;
165 using __valid_digit = typename _Digit<_Base, _Dig>::__valid;
166 using type
167 = __ull_constant<__next::value * (__valid_digit{} ? _Base : 1ULL)>;
168 };
169
170 template<unsigned _Base, char _Dig>
171 struct _Power_help<_Base, _Dig>
172 {
173 using __valid_digit = typename _Digit<_Base, _Dig>::__valid;
174 using type = __ull_constant<__valid_digit::value>;
175 };
176
177 template<unsigned _Base, char... _Digs>
178 struct _Power : _Power_help<_Base, _Digs...>::type
179 { };
180
181 template<unsigned _Base>
182 struct _Power<_Base> : __ull_constant<0>
183 { };
184
185 //------------------------------------------------------------------------------
186
187 template<unsigned _Base, unsigned long long _Pow, char _Dig, char... _Digs>
188 struct _Number_help
189 {
190 using __digit = _Digit<_Base, _Dig>;
191 using __valid_digit = typename __digit::__valid;
192 using __next = _Number_help<_Base,
193 __valid_digit::value ? _Pow / _Base : _Pow,
194 _Digs...>;
195 using type = __ull_constant<_Pow * __digit::value + __next::type::value>;
196 static_assert((type::value / _Pow) == __digit::value,
197 "integer literal does not fit in unsigned long long");
198 };
199
200 // Skip past digit separators:
201 template<unsigned _Base, unsigned long long _Pow, char _Dig, char..._Digs>
202 struct _Number_help<_Base, _Pow, '\'', _Dig, _Digs...>
203 : _Number_help<_Base, _Pow, _Dig, _Digs...>
204 { };
205
206 // Terminating case for recursion:
207 template<unsigned _Base, char _Dig>
208 struct _Number_help<_Base, 1ULL, _Dig>
209 {
210 using type = __ull_constant<_Digit<_Base, _Dig>::value>;
211 };
212
213 template<unsigned _Base, char... _Digs>
214 struct _Number
215 : _Number_help<_Base, _Power<_Base, _Digs...>::value, _Digs...>::type
216 { };
217
218 template<unsigned _Base>
219 struct _Number<_Base>
220 : __ull_constant<0>
221 { };
222
223 //------------------------------------------------------------------------------
224
225 template<char... _Digs>
226 struct _Parse_int;
227
228 template<char... _Digs>
229 struct _Parse_int<'0', 'b', _Digs...>
230 : _Number<2U, _Digs...>::type
231 { };
232
233 template<char... _Digs>
234 struct _Parse_int<'0', 'B', _Digs...>
235 : _Number<2U, _Digs...>::type
236 { };
237
238 template<char... _Digs>
239 struct _Parse_int<'0', 'x', _Digs...>
240 : _Number<16U, _Digs...>::type
241 { };
242
243 template<char... _Digs>
244 struct _Parse_int<'0', 'X', _Digs...>
245 : _Number<16U, _Digs...>::type
246 { };
247
248 template<char... _Digs>
249 struct _Parse_int<'0', _Digs...>
250 : _Number<8U, _Digs...>::type
251 { };
252
253 template<char... _Digs>
254 struct _Parse_int
255 : _Number<10U, _Digs...>::type
256 { };
257
258 } // namespace __parse_int
259
260
261 namespace __select_int
262 {
263 template<unsigned long long _Val, typename... _Ints>
264 struct _Select_int_base;
265
266 template<unsigned long long _Val, typename _IntType, typename... _Ints>
267 struct _Select_int_base<_Val, _IntType, _Ints...>
268 : conditional_t<(_Val <= std::numeric_limits<_IntType>::max()),
269 integral_constant<_IntType, _Val>,
270 _Select_int_base<_Val, _Ints...>>
271 { };
272
273 template<unsigned long long _Val>
274 struct _Select_int_base<_Val>
275 { };
276
277 template<char... _Digs>
278 using _Select_int = typename _Select_int_base<
279 __parse_int::_Parse_int<_Digs...>::value,
280 unsigned char,
281 unsigned short,
282 unsigned int,
283 unsigned long,
284 unsigned long long
285 >::type;
286
287 } // namespace __select_int
288
289 _GLIBCXX_END_NAMESPACE_VERSION
290 } // namespace std
291
292 #endif // __cplusplus > 201103L
293
294 #endif // _GLIBCXX_PARSE_NUMBERS_H
295