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Edit File: numeric_traits.h

// -*- C++ -*- // Copyright (C) 2007-2021 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the terms // of the GNU General Public License as published by the Free Software // Foundation; either version 3, or (at your option) any later // version. // This library is distributed in the hope that it will be useful, but // WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU // General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file ext/numeric_traits.h * This file is a GNU extension to the Standard C++ Library. */ #ifndef _EXT_NUMERIC_TRAITS #define _EXT_NUMERIC_TRAITS 1 #pragma GCC system_header #include <bits/cpp_type_traits.h> #include <ext/type_traits.h> namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION // Compile time constants for builtin types. // In C++98 std::numeric_limits member functions are not constant expressions // (that changed in C++11 with the addition of 'constexpr'). // Even for C++11, this header is smaller than <limits> and can be used // when only is_signed, digits, min, or max values are needed for integers, // or is_signed, digits10, max_digits10, or max_exponent10 for floats. // Unlike __is_integer (and std::is_integral) this trait is true for // non-standard built-in integer types such as __int128 and __int20. template<typename _Tp> struct __is_integer_nonstrict : public std::__is_integer<_Tp> { using std::__is_integer<_Tp>::__value; // The number of bits in the value representation. enum { __width = __value ? sizeof(_Tp) * __CHAR_BIT__ : 0 }; }; template<typename _Value> struct __numeric_traits_integer { #if __cplusplus >= 201103L static_assert(__is_integer_nonstrict<_Value>::__value, "invalid specialization"); #endif // NB: these two are also available in std::numeric_limits as compile // time constants, but <limits> is big and we can avoid including it. static const bool __is_signed = (_Value)(-1) < 0; static const int __digits = __is_integer_nonstrict<_Value>::__width - __is_signed; // The initializers must be constants so that __max and __min are too. static const _Value __max = __is_signed ? (((((_Value)1 << (__digits - 1)) - 1) << 1) + 1) : ~(_Value)0; static const _Value __min = __is_signed ? -__max - 1 : (_Value)0; }; template<typename _Value> const _Value __numeric_traits_integer<_Value>::__min; template<typename _Value> const _Value __numeric_traits_integer<_Value>::__max; template<typename _Value> const bool __numeric_traits_integer<_Value>::__is_signed; template<typename _Value> const int __numeric_traits_integer<_Value>::__digits; // Enable __numeric_traits_integer for types where the __is_integer_nonstrict // primary template doesn't give the right answer. #define _GLIBCXX_INT_N_TRAITS(T, WIDTH) \ template<> struct __is_integer_nonstrict<T> \ { \ enum { __value = 1 }; \ typedef std::__true_type __type; \ enum { __width = WIDTH }; \ }; \ template<> struct __is_integer_nonstrict<unsigned T> \ { \ enum { __value = 1 }; \ typedef std::__true_type __type; \ enum { __width = WIDTH }; \ }; // We need to specify the width for some __intNN types because they // have padding bits, e.g. the object representation of __int20 has 32 bits, // but its width (number of bits in the value representation) is only 20. #if defined __GLIBCXX_TYPE_INT_N_0 && __GLIBCXX_BITSIZE_INT_N_0 % __CHAR_BIT__ _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_0, __GLIBCXX_BITSIZE_INT_N_0) #endif #if defined __GLIBCXX_TYPE_INT_N_1 && __GLIBCXX_BITSIZE_INT_N_1 % __CHAR_BIT__ _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_1, __GLIBCXX_BITSIZE_INT_N_1) #endif #if defined __GLIBCXX_TYPE_INT_N_2 && __GLIBCXX_BITSIZE_INT_N_2 % __CHAR_BIT__ _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_2, __GLIBCXX_BITSIZE_INT_N_2) #endif #if defined __GLIBCXX_TYPE_INT_N_3 && __GLIBCXX_BITSIZE_INT_N_3 % __CHAR_BIT__ _GLIBCXX_INT_N_TRAITS(__GLIBCXX_TYPE_INT_N_3, __GLIBCXX_BITSIZE_INT_N_3) #endif #if defined __STRICT_ANSI__ && defined __SIZEOF_INT128__ // In strict modes __is_integer<__int128> is false, // but we still want to define __numeric_traits_integer<__int128>. _GLIBCXX_INT_N_TRAITS(__int128, 128) #endif #undef _GLIBCXX_INT_N_TRAITS #if __cplusplus >= 201103L /// Convenience alias for __numeric_traits<integer-type>. template<typename _Tp> using __int_traits = __numeric_traits_integer<_Tp>; #endif #define __glibcxx_floating(_Tp, _Fval, _Dval, _LDval) \ (std::__are_same<_Tp, float>::__value ? _Fval \ : std::__are_same<_Tp, double>::__value ? _Dval : _LDval) #define __glibcxx_max_digits10(_Tp) \ (2 + __glibcxx_floating(_Tp, __FLT_MANT_DIG__, __DBL_MANT_DIG__, \ __LDBL_MANT_DIG__) * 643L / 2136) #define __glibcxx_digits10(_Tp) \ __glibcxx_floating(_Tp, __FLT_DIG__, __DBL_DIG__, __LDBL_DIG__) #define __glibcxx_max_exponent10(_Tp) \ __glibcxx_floating(_Tp, __FLT_MAX_10_EXP__, __DBL_MAX_10_EXP__, \ __LDBL_MAX_10_EXP__) // N.B. this only supports float, double and long double (no __float128 etc.) template<typename _Value> struct __numeric_traits_floating { // Only floating point types. See N1822. static const int __max_digits10 = __glibcxx_max_digits10(_Value); // See above comment... static const bool __is_signed = true; static const int __digits10 = __glibcxx_digits10(_Value); static const int __max_exponent10 = __glibcxx_max_exponent10(_Value); }; template<typename _Value> const int __numeric_traits_floating<_Value>::__max_digits10; template<typename _Value> const bool __numeric_traits_floating<_Value>::__is_signed; template<typename _Value> const int __numeric_traits_floating<_Value>::__digits10; template<typename _Value> const int __numeric_traits_floating<_Value>::__max_exponent10; #undef __glibcxx_floating #undef __glibcxx_max_digits10 #undef __glibcxx_digits10 #undef __glibcxx_max_exponent10 template<typename _Value> struct __numeric_traits : public __numeric_traits_integer<_Value> { }; template<> struct __numeric_traits<float> : public __numeric_traits_floating<float> { }; template<> struct __numeric_traits<double> : public __numeric_traits_floating<double> { }; template<> struct __numeric_traits<long double> : public __numeric_traits_floating<long double> { }; #ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT # if defined __LONG_DOUBLE_IEEE128__ // long double is __ieee128, define traits for __ibm128 template<> struct __numeric_traits_floating<__ibm128> { static const int __max_digits10 = 33; static const bool __is_signed = true; static const int __digits10 = 31; static const int __max_exponent10 = 308; }; template<> struct __numeric_traits<__ibm128> : public __numeric_traits_floating<__ibm128> { }; # elif defined __LONG_DOUBLE_IBM128__ // long double is __ibm128, define traits for __ieee128 template<> struct __numeric_traits_floating<__ieee128> { static const int __max_digits10 = 36; static const bool __is_signed = true; static const int __digits10 = 33; static const int __max_exponent10 = 4932; }; template<> struct __numeric_traits<__ieee128> : public __numeric_traits_floating<__ieee128> { }; # endif #endif _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif