# type_traits.h

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    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 <bits/c++config.h>
    00041 #include <bits/cpp_type_traits.h>
    00042
    00043 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00044
    00045   // Define a nested type if some predicate holds.
    00046   template<bool, typename>
    00047     struct __enable_if
    00048     { };
    00049
    00050   template<typename _Tp>
    00051     struct __enable_if<true, _Tp>
    00052     { typedef _Tp __type; };
    00053
    00054
    00055   // Conditional expression for types. If true, first, if false, second.
    00056   template<bool _Cond, typename _Iftrue, typename _Iffalse>
    00057     struct __conditional_type
    00058     { typedef _Iftrue __type; };
    00059
    00060   template<typename _Iftrue, typename _Iffalse>
    00061     struct __conditional_type<false, _Iftrue, _Iffalse>
    00062     { typedef _Iffalse __type; };
    00063
    00064
    00065   // Given an integral builtin type, return the corresponding unsigned type.
    00066   template<typename _Tp>
    00067     struct __add_unsigned
    00068     {
    00069     private:
    00070       typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
    00071
    00072     public:
    00073       typedef typename __if_type::__type __type;
    00074     };
    00075
    00076   template<>
    00077     struct __add_unsigned<char>
    00078     { typedef unsigned char __type; };
    00079
    00080   template<>
    00081     struct __add_unsigned<signed char>
    00082     { typedef unsigned char __type; };
    00083
    00084   template<>
    00085     struct __add_unsigned<short>
    00086     { typedef unsigned short __type; };
    00087
    00088   template<>
    00089     struct __add_unsigned<int>
    00090     { typedef unsigned int __type; };
    00091
    00092   template<>
    00093     struct __add_unsigned<long>
    00094     { typedef unsigned long __type; };
    00095
    00096   template<>
    00097     struct __add_unsigned<long long>
    00098     { typedef unsigned long long __type; };
    00099
    00100   // Declare but don't define.
    00101   template<>
    00102     struct __add_unsigned<bool>;
    00103
    00104   template<>
    00105     struct __add_unsigned<wchar_t>;
    00106
    00107
    00108   // Given an integral builtin type, return the corresponding signed type.
    00109   template<typename _Tp>
    00110     struct __remove_unsigned
    00111     {
    00112     private:
    00113       typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
    00114
    00115     public:
    00116       typedef typename __if_type::__type __type;
    00117     };
    00118
    00119   template<>
    00120     struct __remove_unsigned<char>
    00121     { typedef signed char __type; };
    00122
    00123   template<>
    00124     struct __remove_unsigned<unsigned char>
    00125     { typedef signed char __type; };
    00126
    00127   template<>
    00128     struct __remove_unsigned<unsigned short>
    00129     { typedef short __type; };
    00130
    00131   template<>
    00132     struct __remove_unsigned<unsigned int>
    00133     { typedef int __type; };
    00134
    00135   template<>
    00136     struct __remove_unsigned<unsigned long>
    00137     { typedef long __type; };
    00138
    00139   template<>
    00140     struct __remove_unsigned<unsigned long long>
    00141     { typedef long long __type; };
    00142
    00143   // Declare but don't define.
    00144   template<>
    00145     struct __remove_unsigned<bool>;
    00146
    00147   template<>
    00148     struct __remove_unsigned<wchar_t>;
    00149
    00150
    00151   // For use in string and vstring.
    00152   template<typename _Type>
    00153     inline bool
    00154     __is_null_pointer(_Type* __ptr)
    00155     { return __ptr == 0; }
    00156
    00157   template<typename _Type>
    00158     inline bool
    00159     __is_null_pointer(_Type)
    00160     { return false; }
    00161
    00162
    00163   // For complex and cmath
    00164   template<typename _Tp, bool = std::__is_integer<_Tp>::__value>
    00165     struct __promote
    00166     { typedef double __type; };
    00167
    00168   template<typename _Tp>
    00169     struct __promote<_Tp, false>
    00170     { typedef _Tp __type; };
    00171
    00172   template<typename _Tp, typename _Up>
    00173     struct __promote_2
    00174     {
    00175     private:
    00176       typedef typename __promote<_Tp>::__type __type1;
    00177       typedef typename __promote<_Up>::__type __type2;
    00178
    00179     public:
    00180       typedef __typeof__(__type1() + __type2()) __type;
    00181     };
    00182
    00183   template<typename _Tp, typename _Up, typename _Vp>
    00184     struct __promote_3
    00185     {
    00186     private:
    00187       typedef typename __promote<_Tp>::__type __type1;
    00188       typedef typename __promote<_Up>::__type __type2;
    00189       typedef typename __promote<_Vp>::__type __type3;
    00190
    00191     public:
    00192       typedef __typeof__(__type1() + __type2() + __type3()) __type;
    00193     };
    00194
    00195   template<typename _Tp, typename _Up, typename _Vp, typename _Wp>
    00196     struct __promote_4
    00197     {
    00198     private:
    00199       typedef typename __promote<_Tp>::__type __type1;
    00200       typedef typename __promote<_Up>::__type __type2;
    00201       typedef typename __promote<_Vp>::__type __type3;
    00202       typedef typename __promote<_Wp>::__type __type4;
    00203
    00204     public:
    00205       typedef __typeof__(__type1() + __type2() + __type3() + __type4()) __type;
    00206     };
    00207
    00208 _GLIBCXX_END_NAMESPACE
    00209
    00210 #endif