1// Components for compile-time parsing of numbers -*- C++ -*- 
2 
3// Copyright (C) 2013-2021 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 
42namespace std _GLIBCXX_VISIBILITY(default) 
43{ 
44_GLIBCXX_BEGIN_NAMESPACE_VERSION 
45 
46namespace __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 
262namespace __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 
296