parse_numbers.h revision 1.3 
1// Components for compile-time parsing of numbers -*- C++ -*-
2
3// Copyright (C) 2013-2017 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
41namespace std _GLIBCXX_VISIBILITY(default)
42{
43_GLIBCXX_BEGIN_NAMESPACE_VERSION
44
45namespace __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, unsigned long long _Pow, char _Dig>
208    struct _Number_help<_Base, _Pow, _Dig>
209    {
210      //static_assert(_Pow == 1U, "power should be one");
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 <= std::numeric_limits<_IntType>::max()),
270		    integral_constant<_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 // __cplusplus > 201103L
294
295#endif // _GLIBCXX_PARSE_NUMBERS_H
296