# numeric_traits.h

Go to the documentation of this file.

    00001 // -*- C++ -*-
    00002
    00003 // Copyright (C) 2007, 2009 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
    00017 // permissions described in the GCC Runtime Library Exception, version
    00018 // 3.1, as published by the Free Software Foundation.
    00019
    00020 // You should have received a copy of the GNU General Public License and
    00021 // a copy of the GCC Runtime Library Exception along with this program;
    00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    00023 // <http://www.gnu.org/licenses/>.
    00024
    00025 /** @file ext/numeric_traits.h
    00026  *  This file is a GNU extension to the Standard C++ Library.
    00027  */
    00028
    00029 #ifndef _EXT_NUMERIC_TRAITS
    00030 #define _EXT_NUMERIC_TRAITS 1
    00031
    00032 #pragma GCC system_header
    00033
    00034 #include <bits/cpp_type_traits.h>
    00035 #include <ext/type_traits.h>
    00036
    00037 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00038
    00039   // Compile time constants for builtin types.
    00040   // Sadly std::numeric_limits member functions cannot be used for this.
    00041 #define __glibcxx_signed(_Tp) ((_Tp)(-1) < 0)
    00042 #define __glibcxx_digits(_Tp) \
    00043   (sizeof(_Tp) * __CHAR_BIT__ - __glibcxx_signed(_Tp))
    00044
    00045 #define __glibcxx_min(_Tp) \
    00046   (__glibcxx_signed(_Tp) ? (_Tp)1 << __glibcxx_digits(_Tp) : (_Tp)0)
    00047
    00048 #define __glibcxx_max(_Tp) \
    00049   (__glibcxx_signed(_Tp) ? \
    00050    (((((_Tp)1 << (__glibcxx_digits(_Tp) - 1)) - 1) << 1) + 1) : ~(_Tp)0)
    00051
    00052   template<typename _Value>
    00053     struct __numeric_traits_integer
    00054     {
    00055       // Only integers for initialization of member constant.
    00056       static const _Value __min = __glibcxx_min(_Value);
    00057       static const _Value __max = __glibcxx_max(_Value);
    00058
    00059       // NB: these two also available in std::numeric_limits as compile
    00060       // time constants, but <limits> is big and we avoid including it.
    00061       static const bool __is_signed = __glibcxx_signed(_Value);
    00062       static const int __digits = __glibcxx_digits(_Value);
    00063     };
    00064
    00065   template<typename _Value>
    00066     const _Value __numeric_traits_integer<_Value>::__min;
    00067
    00068   template<typename _Value>
    00069     const _Value __numeric_traits_integer<_Value>::__max;
    00070
    00071   template<typename _Value>
    00072     const bool __numeric_traits_integer<_Value>::__is_signed;
    00073
    00074   template<typename _Value>
    00075     const int __numeric_traits_integer<_Value>::__digits;
    00076
    00077 #undef __glibcxx_signed
    00078 #undef __glibcxx_digits
    00079 #undef __glibcxx_min
    00080 #undef __glibcxx_max
    00081
    00082 #define __glibcxx_floating(_Tp, _Fval, _Dval, _LDval) \
    00083   (std::__are_same<_Tp, float>::__value ? _Fval \
    00084    : std::__are_same<_Tp, double>::__value ? _Dval : _LDval)
    00085
    00086 #define __glibcxx_max_digits10(_Tp) \
    00087   (2 + __glibcxx_floating(_Tp, __FLT_MANT_DIG__, __DBL_MANT_DIG__, \
    00088               __LDBL_MANT_DIG__) * 3010 / 10000)
    00089
    00090 #define __glibcxx_digits10(_Tp) \
    00091   __glibcxx_floating(_Tp, __FLT_DIG__, __DBL_DIG__, __LDBL_DIG__)
    00092
    00093 #define __glibcxx_max_exponent10(_Tp) \
    00094   __glibcxx_floating(_Tp, __FLT_MAX_10_EXP__, __DBL_MAX_10_EXP__, \
    00095              __LDBL_MAX_10_EXP__)
    00096
    00097   template<typename _Value>
    00098     struct __numeric_traits_floating
    00099     {
    00100       // Only floating point types. See N1822.
    00101       static const int __max_digits10 = __glibcxx_max_digits10(_Value);
    00102
    00103       // See above comment...
    00104       static const bool __is_signed = true;
    00105       static const int __digits10 = __glibcxx_digits10(_Value);
    00106       static const int __max_exponent10 = __glibcxx_max_exponent10(_Value);
    00107     };
    00108
    00109   template<typename _Value>
    00110     const int __numeric_traits_floating<_Value>::__max_digits10;
    00111
    00112   template<typename _Value>
    00113     const bool __numeric_traits_floating<_Value>::__is_signed;
    00114
    00115   template<typename _Value>
    00116     const int __numeric_traits_floating<_Value>::__digits10;
    00117
    00118   template<typename _Value>
    00119     const int __numeric_traits_floating<_Value>::__max_exponent10;
    00120
    00121   template<typename _Value>
    00122     struct __numeric_traits
    00123     : public __conditional_type<std::__is_integer<_Value>::__value,
    00124                 __numeric_traits_integer<_Value>,
    00125                 __numeric_traits_floating<_Value> >::__type
    00126     { };
    00127
    00128 _GLIBCXX_END_NAMESPACE
    00129
    00130 #undef __glibcxx_floating
    00131 #undef __glibcxx_max_digits10
    00132 #undef __glibcxx_digits10
    00133 #undef __glibcxx_max_exponent10
    00134
    00135 #endif