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