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1 | // Minimal replacement for numeric_limits of integers. -*- C++ -*- |
2 | ||
3 | // Copyright (C) 2020 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/int_limits.h | |
26 | * This is an internal header file, included by other library headers. | |
27 | * Do not attempt to use it directly. @headername{limits} | |
28 | */ | |
29 | ||
30 | #ifndef _GLIBCXX_INT_LIMITS_H | |
31 | #define _GLIBCXX_INT_LIMITS_H 1 | |
32 | ||
33 | #pragma GCC system_header | |
34 | ||
35 | #if __cplusplus >= 201103L | |
36 | #include <bits/c++config.h> | |
37 | ||
38 | namespace std _GLIBCXX_VISIBILITY(default) | |
39 | { | |
40 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
41 | namespace __detail | |
42 | { | |
43 | // This template is used for arbitrary signed and unsigned integer types | |
44 | // (by headers <bit> and <charconv>) and for specific integer types | |
45 | // (by <memory_resource> and <string_view>) but also for char (<charconv>). | |
46 | // For simplicity's sake, all integral types except bool are supported. | |
47 | ||
48 | // Lightweight alternative to numeric_limits<signed integer type>. | |
49 | template<typename _Tp, bool = is_signed<_Tp>::value> | |
50 | struct __int_limits | |
51 | { | |
52 | static_assert(is_integral<_Tp>::value, "unsupported specialization"); | |
53 | using _Up = typename make_unsigned<_Tp>::type; | |
54 | static constexpr int digits = sizeof(_Tp) * __CHAR_BIT__ - 1; | |
55 | static constexpr _Tp min() noexcept { return _Tp(_Up(1) << digits); } | |
56 | static constexpr _Tp max() noexcept { return _Tp(_Up(~_Up(0)) >> 1); } | |
57 | }; | |
58 | ||
59 | // Lightweight alternative to numeric_limits<unsigned integer type>. | |
60 | template<typename _Tp> | |
61 | struct __int_limits<_Tp, false> | |
62 | { | |
63 | static_assert(is_integral<_Tp>::value, "unsupported specialization"); | |
64 | static constexpr int digits = sizeof(_Tp) * __CHAR_BIT__; | |
65 | static constexpr _Tp min() noexcept { return 0; } | |
66 | static constexpr _Tp max() noexcept { return _Tp(-1); } | |
67 | }; | |
68 | ||
69 | template<> struct __int_limits<bool>; // not defined | |
70 | } | |
71 | _GLIBCXX_END_NAMESPACE_VERSION | |
72 | } // namespace | |
73 | #endif // C++11 | |
74 | #endif // _GLIBCXX_INT_LIMITS_H |