// -*- C++ -*-
-// Copyright (C) 2007 Free Software Foundation, Inc.
+// 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 2, or (at your option) any later
+// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
-// You should have received a copy of the GNU General Public License along
-// with this library; see the file COPYING. If not, write to the Free
-// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
-// USA.
-
-// As a special exception, you may use this file as part of a free
-// software library without restriction. Specifically, if other files
-// instantiate templates or use macros or inline functions from this
-// file, or you compile this file and link it with other files to
-// produce an executable, this file does not by itself cause the
-// resulting executable to be covered by the GNU General Public
-// License. This exception does not however invalidate any other
-// reasons why the executable file might be covered by the GNU General
-// Public License.
+// 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.
#include <bits/cpp_type_traits.h>
#include <ext/type_traits.h>
-_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
+namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
// Compile time constants for builtin types.
- // Sadly std::numeric_limits member functions cannot be used for this.
-#define __glibcxx_signed(_Tp) ((_Tp)(-1) < 0)
-#define __glibcxx_digits(_Tp) \
- (sizeof(_Tp) * __CHAR_BIT__ - __glibcxx_signed(_Tp))
-
-#define __glibcxx_min(_Tp) \
- (__glibcxx_signed(_Tp) ? (_Tp)1 << __glibcxx_digits(_Tp) : (_Tp)0)
+ // 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;
-#define __glibcxx_max(_Tp) \
- (__glibcxx_signed(_Tp) ? \
- (((((_Tp)1 << (__glibcxx_digits(_Tp) - 1)) - 1) << 1) + 1) : ~(_Tp)0)
+ // The number of bits in the value representation.
+ enum { __width = __value ? sizeof(_Tp) * __CHAR_BIT__ : 0 };
+ };
template<typename _Value>
struct __numeric_traits_integer
{
- // Only integers for initialization of member constant.
- static const _Value __min = __glibcxx_min(_Value);
- static const _Value __max = __glibcxx_max(_Value);
-
- // NB: these two also available in std::numeric_limits as compile
- // time constants, but <limits> is big and we avoid including it.
- static const bool __is_signed = __glibcxx_signed(_Value);
- static const int __digits = __glibcxx_digits(_Value);
+#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>
template<typename _Value>
const int __numeric_traits_integer<_Value>::__digits;
-#undef __glibcxx_signed
-#undef __glibcxx_digits
-#undef __glibcxx_min
-#undef __glibcxx_max
+ // 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 \
#define __glibcxx_max_digits10(_Tp) \
(2 + __glibcxx_floating(_Tp, __FLT_MANT_DIG__, __DBL_MANT_DIG__, \
- __LDBL_MANT_DIG__) * 3010 / 10000)
+ __LDBL_MANT_DIG__) * 643L / 2136)
#define __glibcxx_digits10(_Tp) \
__glibcxx_floating(_Tp, __FLT_DIG__, __DBL_DIG__, __LDBL_DIG__)
__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.
+ // Only floating point types. See N1822.
static const int __max_digits10 = __glibcxx_max_digits10(_Value);
// See above comment...
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 __conditional_type<std::__is_integer<_Value>::__value,
- __numeric_traits_integer<_Value>,
- __numeric_traits_floating<_Value> >::__type
+ : public __numeric_traits_integer<_Value>
{ };
-_GLIBCXX_END_NAMESPACE
+ template<>
+ struct __numeric_traits<float>
+ : public __numeric_traits_floating<float>
+ { };
-#undef __glibcxx_floating
-#undef __glibcxx_max_digits10
-#undef __glibcxx_digits10
-#undef __glibcxx_max_exponent10
+ 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
+#endif