# numeric_traits.h

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    00001 // -*- C++ -*-
    00002
    00003 // Copyright (C) 2007 Free Software Foundation, Inc.
    00004 //
    00005 // This file is part of the GNU ISO C++ Library.  This library is free
    00006 // software; you can redistribute it and/or modify it under the terms
    00007 // of the GNU General Public License as published by the Free Software
    00008 // Foundation; either version 2, or (at your option) any later
    00009 // version.
    00010
    00011 // This library is distributed in the hope that it will be useful, but
    00012 // WITHOUT ANY WARRANTY; without even the implied warranty of
    00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    00014 // General Public License for more details.
    00015
    00016 // You should have received a copy of the GNU General Public License along
    00017 // with this library; see the file COPYING.  If not, write to the Free
    00018 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
    00019 // USA.
    00020
    00021 // As a special exception, you may use this file as part of a free
    00022 // software library without restriction.  Specifically, if other files
    00023 // instantiate templates or use macros or inline functions from this
    00024 // file, or you compile this file and link it with other files to
    00025 // produce an executable, this file does not by itself cause the
    00026 // resulting executable to be covered by the GNU General Public
    00027 // License.  This exception does not however invalidate any other
    00028 // reasons why the executable file might be covered by the GNU General
    00029 // Public License.
    00030
    00031 /** @file ext/numeric_traits.h
    00032  *  This file is a GNU extension to the Standard C++ Library.
    00033  */
    00034
    00035 #ifndef _EXT_NUMERIC_TRAITS
    00036 #define _EXT_NUMERIC_TRAITS 1
    00037
    00038 #pragma GCC system_header
    00039
    00040 #include <bits/cpp_type_traits.h>
    00041 #include <ext/type_traits.h>
    00042
    00043 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00044
    00045   // Compile time constants for builtin types.
    00046   // Sadly std::numeric_limits member functions cannot be used for this.
    00047 #define __glibcxx_signed(_Tp) ((_Tp)(-1) < 0)
    00048 #define __glibcxx_digits(_Tp) \
    00049   (sizeof(_Tp) * __CHAR_BIT__ - __glibcxx_signed(_Tp))
    00050
    00051 #define __glibcxx_min(_Tp) \
    00052   (__glibcxx_signed(_Tp) ? (_Tp)1 << __glibcxx_digits(_Tp) : (_Tp)0)
    00053
    00054 #define __glibcxx_max(_Tp) \
    00055   (__glibcxx_signed(_Tp) ? \
    00056    (((((_Tp)1 << (__glibcxx_digits(_Tp) - 1)) - 1) << 1) + 1) : ~(_Tp)0)
    00057
    00058   template<typename _Value>
    00059     struct __numeric_traits_integer
    00060     {
    00061       // Only integers for initialization of member constant.
    00062       static const _Value __min = __glibcxx_min(_Value);
    00063       static const _Value __max = __glibcxx_max(_Value);
    00064
    00065       // NB: these two also available in std::numeric_limits as compile
    00066       // time constants, but <limits> is big and we avoid including it.
    00067       static const bool __is_signed = __glibcxx_signed(_Value);
    00068       static const int __digits = __glibcxx_digits(_Value);
    00069     };
    00070
    00071   template<typename _Value>
    00072     const _Value __numeric_traits_integer<_Value>::__min;
    00073
    00074   template<typename _Value>
    00075     const _Value __numeric_traits_integer<_Value>::__max;
    00076
    00077   template<typename _Value>
    00078     const bool __numeric_traits_integer<_Value>::__is_signed;
    00079
    00080   template<typename _Value>
    00081     const int __numeric_traits_integer<_Value>::__digits;
    00082
    00083 #undef __glibcxx_signed
    00084 #undef __glibcxx_digits
    00085 #undef __glibcxx_min
    00086 #undef __glibcxx_max
    00087
    00088 #define __glibcxx_floating(_Tp, _Fval, _Dval, _LDval) \
    00089   (std::__are_same<_Tp, float>::__value ? _Fval \
    00090    : std::__are_same<_Tp, double>::__value ? _Dval : _LDval)
    00091
    00092 #define __glibcxx_max_digits10(_Tp) \
    00093   (2 + __glibcxx_floating(_Tp, __FLT_MANT_DIG__, __DBL_MANT_DIG__, \
    00094               __LDBL_MANT_DIG__) * 3010 / 10000)
    00095
    00096 #define __glibcxx_digits10(_Tp) \
    00097   __glibcxx_floating(_Tp, __FLT_DIG__, __DBL_DIG__, __LDBL_DIG__)
    00098
    00099 #define __glibcxx_max_exponent10(_Tp) \
    00100   __glibcxx_floating(_Tp, __FLT_MAX_10_EXP__, __DBL_MAX_10_EXP__, \
    00101              __LDBL_MAX_10_EXP__)
    00102
    00103   template<typename _Value>
    00104     struct __numeric_traits_floating
    00105     {
    00106       // Only floating point types. See N1822.
    00107       static const int __max_digits10 = __glibcxx_max_digits10(_Value);
    00108
    00109       // See above comment...
    00110       static const bool __is_signed = true;
    00111       static const int __digits10 = __glibcxx_digits10(_Value);
    00112       static const int __max_exponent10 = __glibcxx_max_exponent10(_Value);
    00113     };
    00114
    00115   template<typename _Value>
    00116     const int __numeric_traits_floating<_Value>::__max_digits10;
    00117
    00118   template<typename _Value>
    00119     const bool __numeric_traits_floating<_Value>::__is_signed;
    00120
    00121   template<typename _Value>
    00122     const int __numeric_traits_floating<_Value>::__digits10;
    00123
    00124   template<typename _Value>
    00125     const int __numeric_traits_floating<_Value>::__max_exponent10;
    00126
    00127   template<typename _Value>
    00128     struct __numeric_traits
    00129     : public __conditional_type<std::__is_integer<_Value>::__value,
    00130                 __numeric_traits_integer<_Value>,
    00131                 __numeric_traits_floating<_Value> >::__type
    00132     { };
    00133
    00134 _GLIBCXX_END_NAMESPACE
    00135
    00136 #undef __glibcxx_floating
    00137 #undef __glibcxx_max_digits10
    00138 #undef __glibcxx_digits10
    00139 #undef __glibcxx_max_exponent10
    00140
    00141 #endif