# 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 <limits>
    00041 #include <bits/cpp_type_traits.h>
    00042 #include <ext/type_traits.h>
    00043
    00044 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00045
    00046   // Compile time constants for builtin types.
    00047   // Sadly std::numeric_limits member functions cannot be used for this.
    00048 #define __glibcxx_signed(_Tp) ((_Tp)(-1) < 0)
    00049 #define __glibcxx_digits(_Tp) \
    00050   (sizeof(_Tp) * __CHAR_BIT__ - __glibcxx_signed(_Tp))
    00051
    00052 #define __glibcxx_min(_Tp) \
    00053   (__glibcxx_signed(_Tp) ? (_Tp)1 << __glibcxx_digits(_Tp) : (_Tp)0)
    00054
    00055 #define __glibcxx_max(_Tp) \
    00056   (__glibcxx_signed(_Tp) ? \
    00057    (((((_Tp)1 << (__glibcxx_digits(_Tp) - 1)) - 1) << 1) + 1) : ~(_Tp)0)
    00058
    00059   template<typename _Value>
    00060     struct __numeric_traits_integer
    00061     {
    00062       // Only integers for initialization of member constant.
    00063       static const _Value __min = __glibcxx_min(_Value);
    00064       static const _Value __max = __glibcxx_max(_Value);
    00065     };
    00066
    00067   template<typename _Value>
    00068     const _Value __numeric_traits_integer<_Value>::__min;
    00069
    00070   template<typename _Value>
    00071     const _Value __numeric_traits_integer<_Value>::__max;
    00072
    00073   template<typename _Value>
    00074     struct __numeric_traits_floating
    00075     {
    00076       // Only floating point types. See N1822.
    00077       static const int __max_digits10 =
    00078     2 + std::numeric_limits<_Value>::digits * 3010/10000;
    00079     };
    00080
    00081   template<typename _Value>
    00082     const int __numeric_traits_floating<_Value>::__max_digits10;
    00083
    00084   template<typename _Value>
    00085     struct __numeric_traits
    00086     : public __conditional_type<std::__is_integer<_Value>::__value,
    00087                 __numeric_traits_integer<_Value>,
    00088                 __numeric_traits_floating<_Value> >::__type
    00089     { };
    00090
    00091 _GLIBCXX_END_NAMESPACE
    00092
    00093 #undef __glibcxx_signed
    00094 #undef __glibcxx_min
    00095 #undef __glibcxx_max
    00096 #undef __glibcxx_digits
    00097
    00098 #endif