# type_traits.h

Go to the documentation of this file.

    00001 // -*- C++ -*-
    00002
    00003 // Copyright (C) 2005, 2006, 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/type_traits.h
    00032  *  This file is a GNU extension to the Standard C++ Library.
    00033  */
    00034
    00035 #ifndef _EXT_TYPE_TRAITS
    00036 #define _EXT_TYPE_TRAITS 1
    00037
    00038 #pragma GCC system_header
    00039
    00040 #include <cstddef>
    00041 #include <utility>
    00042 #include <bits/cpp_type_traits.h>
    00043
    00044 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00045
    00046   // Define a nested type if some predicate holds.
    00047   template<bool, typename>
    00048     struct __enable_if
    00049     { };
    00050
    00051   template<typename _Tp>
    00052     struct __enable_if<true, _Tp>
    00053     { typedef _Tp __type; };
    00054
    00055
    00056   // Conditional expression for types. If true, first, if false, second.
    00057   template<bool _Cond, typename _Iftrue, typename _Iffalse>
    00058     struct __conditional_type
    00059     { typedef _Iftrue __type; };
    00060
    00061   template<typename _Iftrue, typename _Iffalse>
    00062     struct __conditional_type<false, _Iftrue, _Iffalse>
    00063     { typedef _Iffalse __type; };
    00064
    00065
    00066   // Given an integral builtin type, return the corresponding unsigned type.
    00067   template<typename _Tp>
    00068     struct __add_unsigned
    00069     {
    00070     private:
    00071       typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
    00072
    00073     public:
    00074       typedef typename __if_type::__type __type;
    00075     };
    00076
    00077   template<>
    00078     struct __add_unsigned<char>
    00079     { typedef unsigned char __type; };
    00080
    00081   template<>
    00082     struct __add_unsigned<signed char>
    00083     { typedef unsigned char __type; };
    00084
    00085   template<>
    00086     struct __add_unsigned<short>
    00087     { typedef unsigned short __type; };
    00088
    00089   template<>
    00090     struct __add_unsigned<int>
    00091     { typedef unsigned int __type; };
    00092
    00093   template<>
    00094     struct __add_unsigned<long>
    00095     { typedef unsigned long __type; };
    00096
    00097   template<>
    00098     struct __add_unsigned<long long>
    00099     { typedef unsigned long long __type; };
    00100
    00101   // Declare but don't define.
    00102   template<>
    00103     struct __add_unsigned<bool>;
    00104
    00105   template<>
    00106     struct __add_unsigned<wchar_t>;
    00107
    00108
    00109   // Given an integral builtin type, return the corresponding signed type.
    00110   template<typename _Tp>
    00111     struct __remove_unsigned
    00112     {
    00113     private:
    00114       typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
    00115
    00116     public:
    00117       typedef typename __if_type::__type __type;
    00118     };
    00119
    00120   template<>
    00121     struct __remove_unsigned<char>
    00122     { typedef signed char __type; };
    00123
    00124   template<>
    00125     struct __remove_unsigned<unsigned char>
    00126     { typedef signed char __type; };
    00127
    00128   template<>
    00129     struct __remove_unsigned<unsigned short>
    00130     { typedef short __type; };
    00131
    00132   template<>
    00133     struct __remove_unsigned<unsigned int>
    00134     { typedef int __type; };
    00135
    00136   template<>
    00137     struct __remove_unsigned<unsigned long>
    00138     { typedef long __type; };
    00139
    00140   template<>
    00141     struct __remove_unsigned<unsigned long long>
    00142     { typedef long long __type; };
    00143
    00144   // Declare but don't define.
    00145   template<>
    00146     struct __remove_unsigned<bool>;
    00147
    00148   template<>
    00149     struct __remove_unsigned<wchar_t>;
    00150
    00151 _GLIBCXX_END_NAMESPACE
    00152
    00153 #endif