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The C and C++ Include Header Files
cat -n /usr/include/c++/15/ext/numeric_traits.h
1 // -*- C++ -*- 2 3 // Copyright (C) 2007-2025 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 terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // 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 ext/numeric_traits.h 26 * This file is a GNU extension to the Standard C++ Library. 27 */ 28 29 #ifndef _EXT_NUMERIC_TRAITS 30 #define _EXT_NUMERIC_TRAITS 1 31 32 #ifdef _GLIBCXX_SYSHDR 33 #pragma GCC system_header 34 #endif 35 36 #include <bits/cpp_type_traits.h> 37 #include <ext/type_traits.h> 38 39 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 40 { 41 _GLIBCXX_BEGIN_NAMESPACE_VERSION 42 43 // Compile time constants for builtin types. 44 // In C++98 std::numeric_limits member functions are not constant expressions 45 // (that changed in C++11 with the addition of 'constexpr'). 46 // Even for C++11, this header is smaller than <limits> and can be used 47 // when only is_signed, digits, min, or max values are needed for integers, 48 // or is_signed, digits10, max_digits10, or max_exponent10 for floats. 49 50 // Unlike __is_integer (and std::is_integral) this trait is true for 51 // non-standard built-in integer types such as __int128 and __int20. 52 template<typename _Tp> 53 struct __is_integer_nonstrict 54 : public std::__is_integer<_Tp> 55 { 56 using std::__is_integer<_Tp>::__value; 57 58 // The number of bits in the value representation. 59 enum { __width = __value ? sizeof(_Tp) * __CHAR_BIT__ : 0 }; 60 }; 61 62 template<typename _Value> 63 struct __numeric_traits_integer 64 { 65 #if __cplusplus >= 201103L 66 static_assert(__is_integer_nonstrict<_Value>::__value, 67 "invalid specialization"); 68 #endif 69 70 // NB: these two are also available in std::numeric_limits as compile 71 // time constants, but <limits> is big and we can avoid including it. 72 static const bool __is_signed = (_Value)(-1) < 0; 73 static const int __digits 74 = __is_integer_nonstrict<_Value>::__width - __is_signed; 75 76 // The initializers must be constants so that __max and __min are too. 77 static const _Value __max = __is_signed 78 ? (((((_Value)1 << (__digits - 1)) - 1) << 1) + 1) 79 : ~(_Value)0; 80 static const _Value __min = __is_signed ? -__max - 1 : (_Value)0; 81 }; 82 83 template<typename _Value> 84 const _Value __numeric_traits_integer<_Value>::__min; 85 86 template<typename _Value> 87 const _Value __numeric_traits_integer<_Value>::__max; 88 89 template<typename _Value> 90 const bool __numeric_traits_integer<_Value>::__is_signed; 91 92 template<typename _Value> 93 const int __numeric_traits_integer<_Value>::__digits; 94 95 // Enable __numeric_traits_integer for types where the __is_integer_nonstrict 96 // primary template doesn't give the right answer. 97 #define _GLIBCXX_INT_N_TRAITS(T, WIDTH) \ 98 __extension__ \ 99 template<> struct __is_integer_nonstrict<T> \ 100 { \ 101 enum { __value = 1 }; \ 102 typedef std::__true_type __type; \ 103 enum { __width = WIDTH }; \ 104 }; \ 105 __extension__ \ 106 template<> struct __is_integer_nonstrict<unsigned T> \ 107 { \ 108 enum { __value = 1 }; \ 109 typedef std::__true_type __type; \ 110 enum { __width = WIDTH }; \ 111 }; 112 113 // We need to specify the width for some __intNN types because they 114 // have padding bits, e.g. the object representation of __int20 has 32 bits, 115 // but its width (number of bits in the value representation) is only 20. 116 #if defined __GLIBCXX_TYPE_INT_N_0 && __GLIBCXX_BITSIZE_INT_N_0 % __CHAR_BIT__ 117 _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_0, __GLIBCXX_BITSIZE_INT_N_0) 118 #endif 119 #if defined __GLIBCXX_TYPE_INT_N_1 && __GLIBCXX_BITSIZE_INT_N_1 % __CHAR_BIT__ 120 _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_1, __GLIBCXX_BITSIZE_INT_N_1) 121 #endif 122 #if defined __GLIBCXX_TYPE_INT_N_2 && __GLIBCXX_BITSIZE_INT_N_2 % __CHAR_BIT__ 123 _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_2, __GLIBCXX_BITSIZE_INT_N_2) 124 #endif 125 #if defined __GLIBCXX_TYPE_INT_N_3 && __GLIBCXX_BITSIZE_INT_N_3 % __CHAR_BIT__ 126 _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_3, __GLIBCXX_BITSIZE_INT_N_3) 127 #endif 128 129 #if defined __STRICT_ANSI__ && defined __SIZEOF_INT128__ 130 // In strict modes __is_integer<__int128> is false, 131 // but we still want to define __numeric_traits_integer<__int128>. 132 _GLIBCXX_INT_N_TRAITS(__int128, 128) 133 #endif 134 135 #undef _GLIBCXX_INT_N_TRAITS 136 137 #if __cplusplus >= 201103L 138 /// Convenience alias for __numeric_traits<integer-type>. 139 template<typename _Tp> 140 using __int_traits = __numeric_traits_integer<_Tp>; 141 #endif 142 143 #define __glibcxx_floating(_Tp, _Fval, _Dval, _LDval) \ 144 (std::__are_same<_Tp, float>::__value ? _Fval \ 145 : std::__are_same<_Tp, double>::__value ? _Dval : _LDval) 146 147 #define __glibcxx_max_digits10(_Tp) \ 148 (2 + __glibcxx_floating(_Tp, __FLT_MANT_DIG__, __DBL_MANT_DIG__, \ 149 __LDBL_MANT_DIG__) * 643L / 2136) 150 151 #define __glibcxx_digits10(_Tp) \ 152 __glibcxx_floating(_Tp, __FLT_DIG__, __DBL_DIG__, __LDBL_DIG__) 153 154 #define __glibcxx_max_exponent10(_Tp) \ 155 __glibcxx_floating(_Tp, __FLT_MAX_10_EXP__, __DBL_MAX_10_EXP__, \ 156 __LDBL_MAX_10_EXP__) 157 158 // N.B. this only supports float, double and long double (no __float128 etc.) 159 template<typename _Value> 160 struct __numeric_traits_floating 161 { 162 // Only floating point types. See N1822. 163 static const int __max_digits10 = __glibcxx_max_digits10(_Value); 164 165 // See above comment... 166 static const bool __is_signed = true; 167 static const int __digits10 = __glibcxx_digits10(_Value); 168 static const int __max_exponent10 = __glibcxx_max_exponent10(_Value); 169 }; 170 171 template<typename _Value> 172 const int __numeric_traits_floating<_Value>::__max_digits10; 173 174 template<typename _Value> 175 const bool __numeric_traits_floating<_Value>::__is_signed; 176 177 template<typename _Value> 178 const int __numeric_traits_floating<_Value>::__digits10; 179 180 template<typename _Value> 181 const int __numeric_traits_floating<_Value>::__max_exponent10; 182 183 #undef __glibcxx_floating 184 #undef __glibcxx_max_digits10 185 #undef __glibcxx_digits10 186 #undef __glibcxx_max_exponent10 187 188 template<typename _Value> 189 struct __numeric_traits 190 : public __numeric_traits_integer<_Value> 191 { }; 192 193 template<> 194 struct __numeric_traits<float> 195 : public __numeric_traits_floating<float> 196 { }; 197 198 template<> 199 struct __numeric_traits<double> 200 : public __numeric_traits_floating<double> 201 { }; 202 203 template<> 204 struct __numeric_traits<long double> 205 : public __numeric_traits_floating<long double> 206 { }; 207 208 #ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT 209 # if defined __LONG_DOUBLE_IEEE128__ 210 // long double is __ieee128, define traits for __ibm128 211 template<> 212 struct __numeric_traits_floating<__ibm128> 213 { 214 static const int __max_digits10 = 33; 215 static const bool __is_signed = true; 216 static const int __digits10 = 31; 217 static const int __max_exponent10 = 308; 218 }; 219 template<> 220 struct __numeric_traits<__ibm128> 221 : public __numeric_traits_floating<__ibm128> 222 { }; 223 # elif defined __LONG_DOUBLE_IBM128__ 224 // long double is __ibm128, define traits for __ieee128 225 template<> 226 struct __numeric_traits_floating<__ieee128> 227 { 228 static const int __max_digits10 = 36; 229 static const bool __is_signed = true; 230 static const int __digits10 = 33; 231 static const int __max_exponent10 = 4932; 232 }; 233 template<> 234 struct __numeric_traits<__ieee128> 235 : public __numeric_traits_floating<__ieee128> 236 { }; 237 # endif 238 #endif 239 240 _GLIBCXX_END_NAMESPACE_VERSION 241 } // namespace 242 243 #endif
