# type_traits.h

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    00001 // -*- C++ -*-
    00002
    00003 // Copyright (C) 2005, 2006, 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/type_traits.h
    00026  *  This file is a GNU extension to the Standard C++ Library.
    00027  */
    00028
    00029 #ifndef _EXT_TYPE_TRAITS
    00030 #define _EXT_TYPE_TRAITS 1
    00031
    00032 #pragma GCC system_header
    00033
    00034 #include <bits/c++config.h>
    00035 #include <bits/cpp_type_traits.h>
    00036
    00037 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00038
    00039   // Define a nested type if some predicate holds.
    00040   template<bool, typename>
    00041     struct __enable_if
    00042     { };
    00043
    00044   template<typename _Tp>
    00045     struct __enable_if<true, _Tp>
    00046     { typedef _Tp __type; };
    00047
    00048
    00049   // Conditional expression for types. If true, first, if false, second.
    00050   template<bool _Cond, typename _Iftrue, typename _Iffalse>
    00051     struct __conditional_type
    00052     { typedef _Iftrue __type; };
    00053
    00054   template<typename _Iftrue, typename _Iffalse>
    00055     struct __conditional_type<false, _Iftrue, _Iffalse>
    00056     { typedef _Iffalse __type; };
    00057
    00058
    00059   // Given an integral builtin type, return the corresponding unsigned type.
    00060   template<typename _Tp>
    00061     struct __add_unsigned
    00062     {
    00063     private:
    00064       typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
    00065
    00066     public:
    00067       typedef typename __if_type::__type __type;
    00068     };
    00069
    00070   template<>
    00071     struct __add_unsigned<char>
    00072     { typedef unsigned char __type; };
    00073
    00074   template<>
    00075     struct __add_unsigned<signed char>
    00076     { typedef unsigned char __type; };
    00077
    00078   template<>
    00079     struct __add_unsigned<short>
    00080     { typedef unsigned short __type; };
    00081
    00082   template<>
    00083     struct __add_unsigned<int>
    00084     { typedef unsigned int __type; };
    00085
    00086   template<>
    00087     struct __add_unsigned<long>
    00088     { typedef unsigned long __type; };
    00089
    00090   template<>
    00091     struct __add_unsigned<long long>
    00092     { typedef unsigned long long __type; };
    00093
    00094   // Declare but don't define.
    00095   template<>
    00096     struct __add_unsigned<bool>;
    00097
    00098   template<>
    00099     struct __add_unsigned<wchar_t>;
    00100
    00101
    00102   // Given an integral builtin type, return the corresponding signed type.
    00103   template<typename _Tp>
    00104     struct __remove_unsigned
    00105     {
    00106     private:
    00107       typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
    00108
    00109     public:
    00110       typedef typename __if_type::__type __type;
    00111     };
    00112
    00113   template<>
    00114     struct __remove_unsigned<char>
    00115     { typedef signed char __type; };
    00116
    00117   template<>
    00118     struct __remove_unsigned<unsigned char>
    00119     { typedef signed char __type; };
    00120
    00121   template<>
    00122     struct __remove_unsigned<unsigned short>
    00123     { typedef short __type; };
    00124
    00125   template<>
    00126     struct __remove_unsigned<unsigned int>
    00127     { typedef int __type; };
    00128
    00129   template<>
    00130     struct __remove_unsigned<unsigned long>
    00131     { typedef long __type; };
    00132
    00133   template<>
    00134     struct __remove_unsigned<unsigned long long>
    00135     { typedef long long __type; };
    00136
    00137   // Declare but don't define.
    00138   template<>
    00139     struct __remove_unsigned<bool>;
    00140
    00141   template<>
    00142     struct __remove_unsigned<wchar_t>;
    00143
    00144
    00145   // For use in string and vstring.
    00146   template<typename _Type>
    00147     inline bool
    00148     __is_null_pointer(_Type* __ptr)
    00149     { return __ptr == 0; }
    00150
    00151   template<typename _Type>
    00152     inline bool
    00153     __is_null_pointer(_Type)
    00154     { return false; }
    00155
    00156
    00157   // For complex and cmath
    00158   template<typename _Tp, bool = std::__is_integer<_Tp>::__value>
    00159     struct __promote
    00160     { typedef double __type; };
    00161
    00162   template<typename _Tp>
    00163     struct __promote<_Tp, false>
    00164     { typedef _Tp __type; };
    00165
    00166   template<typename _Tp, typename _Up>
    00167     struct __promote_2
    00168     {
    00169     private:
    00170       typedef typename __promote<_Tp>::__type __type1;
    00171       typedef typename __promote<_Up>::__type __type2;
    00172
    00173     public:
    00174       typedef __typeof__(__type1() + __type2()) __type;
    00175     };
    00176
    00177   template<typename _Tp, typename _Up, typename _Vp>
    00178     struct __promote_3
    00179     {
    00180     private:
    00181       typedef typename __promote<_Tp>::__type __type1;
    00182       typedef typename __promote<_Up>::__type __type2;
    00183       typedef typename __promote<_Vp>::__type __type3;
    00184
    00185     public:
    00186       typedef __typeof__(__type1() + __type2() + __type3()) __type;
    00187     };
    00188
    00189   template<typename _Tp, typename _Up, typename _Vp, typename _Wp>
    00190     struct __promote_4
    00191     {
    00192     private:
    00193       typedef typename __promote<_Tp>::__type __type1;
    00194       typedef typename __promote<_Up>::__type __type2;
    00195       typedef typename __promote<_Vp>::__type __type3;
    00196       typedef typename __promote<_Wp>::__type __type4;
    00197
    00198     public:
    00199       typedef __typeof__(__type1() + __type2() + __type3() + __type4()) __type;
    00200     };
    00201
    00202 _GLIBCXX_END_NAMESPACE
    00203
    00204 #endif