| 1 |
// -*- C++ -*- |
| 2 |
|
| 3 |
// Copyright (C) 2007-2021 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 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 |
#pragma GCC system_header |
| 33 |
|
| 34 |
#include <bits/cpp_type_traits.h> |
| 35 |
#include <ext/type_traits.h> |
| 36 |
|
| 37 |
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) |
| 38 |
{ |
| 39 |
_GLIBCXX_BEGIN_NAMESPACE_VERSION |
| 40 |
|
| 41 |
// Compile time constants for builtin types. |
| 42 |
// In C++98 std::numeric_limits member functions are not constant expressions |
| 43 |
// (that changed in C++11 with the addition of 'constexpr'). |
| 44 |
// Even for C++11, this header is smaller than <limits> and can be used |
| 45 |
// when only is_signed, digits, min, or max values are needed for integers, |
| 46 |
// or is_signed, digits10, max_digits10, or max_exponent10 for floats. |
| 47 |
|
| 48 |
// Unlike __is_integer (and std::is_integral) this trait is true for |
| 49 |
// non-standard built-in integer types such as __int128 and __int20. |
| 50 |
template<typename _Tp> |
| 51 |
struct __is_integer_nonstrict |
| 52 |
: public std::__is_integer<_Tp> |
| 53 |
{ |
| 54 |
using std::__is_integer<_Tp>::__value; |
| 55 |
|
| 56 |
// The number of bits in the value representation. |
| 57 |
enum { __width = __value ? sizeof(_Tp) * __CHAR_BIT__ : 0 }; |
| 58 |
}; |
| 59 |
|
| 60 |
template<typename _Value> |
| 61 |
struct __numeric_traits_integer |
| 62 |
{ |
| 63 |
#if __cplusplus >= 201103L |
| 64 |
static_assert(__is_integer_nonstrict<_Value>::__value, |
| 65 |
"invalid specialization"); |
| 66 |
#endif |
| 67 |
|
| 68 |
// NB: these two are also available in std::numeric_limits as compile |
| 69 |
// time constants, but <limits> is big and we can avoid including it. |
| 70 |
static const bool __is_signed = (_Value)(-1) < 0; |
| 71 |
static const int __digits |
| 72 |
= __is_integer_nonstrict<_Value>::__width - __is_signed; |
| 73 |
|
| 74 |
// The initializers must be constants so that __max and __min are too. |
| 75 |
static const _Value __max = __is_signed |
| 76 |
? (((((_Value)1 << (__digits - 1)) - 1) << 1) + 1) |
| 77 |
: ~(_Value)0; |
| 78 |
static const _Value __min = __is_signed ? -__max - 1 : (_Value)0; |
| 79 |
}; |
| 80 |
|
| 81 |
template<typename _Value> |
| 82 |
const _Value __numeric_traits_integer<_Value>::__min; |
| 83 |
|
| 84 |
template<typename _Value> |
| 85 |
const _Value __numeric_traits_integer<_Value>::__max; |
| 86 |
|
| 87 |
template<typename _Value> |
| 88 |
const bool __numeric_traits_integer<_Value>::__is_signed; |
| 89 |
|
| 90 |
template<typename _Value> |
| 91 |
const int __numeric_traits_integer<_Value>::__digits; |
| 92 |
|
| 93 |
// Enable __numeric_traits_integer for types where the __is_integer_nonstrict |
| 94 |
// primary template doesn't give the right answer. |
| 95 |
#define _GLIBCXX_INT_N_TRAITS(T, WIDTH) \ |
| 96 |
template<> struct __is_integer_nonstrict<T> \ |
| 97 |
{ \ |
| 98 |
enum { __value = 1 }; \ |
| 99 |
typedef std::__true_type __type; \ |
| 100 |
enum { __width = WIDTH }; \ |
| 101 |
}; \ |
| 102 |
template<> struct __is_integer_nonstrict<unsigned T> \ |
| 103 |
{ \ |
| 104 |
enum { __value = 1 }; \ |
| 105 |
typedef std::__true_type __type; \ |
| 106 |
enum { __width = WIDTH }; \ |
| 107 |
}; |
| 108 |
|
| 109 |
// We need to specify the width for some __intNN types because they |
| 110 |
// have padding bits, e.g. the object representation of __int20 has 32 bits, |
| 111 |
// but its width (number of bits in the value representation) is only 20. |
| 112 |
#if defined __GLIBCXX_TYPE_INT_N_0 && __GLIBCXX_BITSIZE_INT_N_0 % __CHAR_BIT__ |
| 113 |
_GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_0, __GLIBCXX_BITSIZE_INT_N_0) |
| 114 |
#endif |
| 115 |
#if defined __GLIBCXX_TYPE_INT_N_1 && __GLIBCXX_BITSIZE_INT_N_1 % __CHAR_BIT__ |
| 116 |
_GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_1, __GLIBCXX_BITSIZE_INT_N_1) |
| 117 |
#endif |
| 118 |
#if defined __GLIBCXX_TYPE_INT_N_2 && __GLIBCXX_BITSIZE_INT_N_2 % __CHAR_BIT__ |
| 119 |
_GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_2, __GLIBCXX_BITSIZE_INT_N_2) |
| 120 |
#endif |
| 121 |
#if defined __GLIBCXX_TYPE_INT_N_3 && __GLIBCXX_BITSIZE_INT_N_3 % __CHAR_BIT__ |
| 122 |
_GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_3, __GLIBCXX_BITSIZE_INT_N_3) |
| 123 |
#endif |
| 124 |
|
| 125 |
#if defined __STRICT_ANSI__ && defined __SIZEOF_INT128__ |
| 126 |
// In strict modes __is_integer<__int128> is false, |
| 127 |
// but we still want to define __numeric_traits_integer<__int128>. |
| 128 |
_GLIBCXX_INT_N_TRAITS(__int128, 128) |
| 129 |
#endif |
| 130 |
|
| 131 |
#undef _GLIBCXX_INT_N_TRAITS |
| 132 |
|
| 133 |
#if __cplusplus >= 201103L |
| 134 |
/// Convenience alias for __numeric_traits<integer-type>. |
| 135 |
template<typename _Tp> |
| 136 |
using __int_traits = __numeric_traits_integer<_Tp>; |
| 137 |
#endif |
| 138 |
|
| 139 |
#define __glibcxx_floating(_Tp, _Fval, _Dval, _LDval) \ |
| 140 |
(std::__are_same<_Tp, float>::__value ? _Fval \ |
| 141 |
: std::__are_same<_Tp, double>::__value ? _Dval : _LDval) |
| 142 |
|
| 143 |
#define __glibcxx_max_digits10(_Tp) \ |
| 144 |
(2 + __glibcxx_floating(_Tp, __FLT_MANT_DIG__, __DBL_MANT_DIG__, \ |
| 145 |
__LDBL_MANT_DIG__) * 643L / 2136) |
| 146 |
|
| 147 |
#define __glibcxx_digits10(_Tp) \ |
| 148 |
__glibcxx_floating(_Tp, __FLT_DIG__, __DBL_DIG__, __LDBL_DIG__) |
| 149 |
|
| 150 |
#define __glibcxx_max_exponent10(_Tp) \ |
| 151 |
__glibcxx_floating(_Tp, __FLT_MAX_10_EXP__, __DBL_MAX_10_EXP__, \ |
| 152 |
__LDBL_MAX_10_EXP__) |
| 153 |
|
| 154 |
// N.B. this only supports float, double and long double (no __float128 etc.) |
| 155 |
template<typename _Value> |
| 156 |
struct __numeric_traits_floating |
| 157 |
{ |
| 158 |
// Only floating point types. See N1822. |
| 159 |
static const int __max_digits10 = __glibcxx_max_digits10(_Value); |
| 160 |
|
| 161 |
// See above comment... |
| 162 |
static const bool __is_signed = true; |
| 163 |
static const int __digits10 = __glibcxx_digits10(_Value); |
| 164 |
static const int __max_exponent10 = __glibcxx_max_exponent10(_Value); |
| 165 |
}; |
| 166 |
|
| 167 |
template<typename _Value> |
| 168 |
const int __numeric_traits_floating<_Value>::__max_digits10; |
| 169 |
|
| 170 |
template<typename _Value> |
| 171 |
const bool __numeric_traits_floating<_Value>::__is_signed; |
| 172 |
|
| 173 |
template<typename _Value> |
| 174 |
const int __numeric_traits_floating<_Value>::__digits10; |
| 175 |
|
| 176 |
template<typename _Value> |
| 177 |
const int __numeric_traits_floating<_Value>::__max_exponent10; |
| 178 |
|
| 179 |
#undef __glibcxx_floating |
| 180 |
#undef __glibcxx_max_digits10 |
| 181 |
#undef __glibcxx_digits10 |
| 182 |
#undef __glibcxx_max_exponent10 |
| 183 |
|
| 184 |
template<typename _Value> |
| 185 |
struct __numeric_traits |
| 186 |
: public __numeric_traits_integer<_Value> |
| 187 |
{ }; |
| 188 |
|
| 189 |
template<> |
| 190 |
struct __numeric_traits<float> |
| 191 |
: public __numeric_traits_floating<float> |
| 192 |
{ }; |
| 193 |
|
| 194 |
template<> |
| 195 |
struct __numeric_traits<double> |
| 196 |
: public __numeric_traits_floating<double> |
| 197 |
{ }; |
| 198 |
|
| 199 |
template<> |
| 200 |
struct __numeric_traits<long double> |
| 201 |
: public __numeric_traits_floating<long double> |
| 202 |
{ }; |
| 203 |
|
| 204 |
#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT |
| 205 |
# if defined __LONG_DOUBLE_IEEE128__ |
| 206 |
// long double is __ieee128, define traits for __ibm128 |
| 207 |
template<> |
| 208 |
struct __numeric_traits_floating<__ibm128> |
| 209 |
{ |
| 210 |
static const int __max_digits10 = 33; |
| 211 |
static const bool __is_signed = true; |
| 212 |
static const int __digits10 = 31; |
| 213 |
static const int __max_exponent10 = 308; |
| 214 |
}; |
| 215 |
template<> |
| 216 |
struct __numeric_traits<__ibm128> |
| 217 |
: public __numeric_traits_floating<__ibm128> |
| 218 |
{ }; |
| 219 |
# elif defined __LONG_DOUBLE_IBM128__ |
| 220 |
// long double is __ibm128, define traits for __ieee128 |
| 221 |
template<> |
| 222 |
struct __numeric_traits_floating<__ieee128> |
| 223 |
{ |
| 224 |
static const int __max_digits10 = 36; |
| 225 |
static const bool __is_signed = true; |
| 226 |
static const int __digits10 = 33; |
| 227 |
static const int __max_exponent10 = 4932; |
| 228 |
}; |
| 229 |
template<> |
| 230 |
struct __numeric_traits<__ieee128> |
| 231 |
: public __numeric_traits_floating<__ieee128> |
| 232 |
{ }; |
| 233 |
# endif |
| 234 |
#endif |
| 235 |
|
| 236 |
_GLIBCXX_END_NAMESPACE_VERSION |
| 237 |
} // namespace |
| 238 |
|
| 239 |
#endif |
