type_traits.h
Go to the documentation of this file.
// -*- C++ -*-
// Copyright (C) 2005-2014 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License as published by the Free Software
// Foundation; either version 3, or (at your option) any later
// version.
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file ext/type_traits.h
* This file is a GNU extension to the Standard C++ Library.
*/
#ifndef _EXT_TYPE_TRAITS
#define _EXT_TYPE_TRAITS 1
#pragma GCC system_header
#include <bits/c++config.h>
#include <bits/cpp_type_traits.h>
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
// Define a nested type if some predicate holds.
template<bool, typename>
struct __enable_if
{ };
template<typename _Tp>
struct __enable_if<true, _Tp>
{ typedef _Tp __type; };
// Conditional expression for types. If true, first, if false, second.
template<bool _Cond, typename _Iftrue, typename _Iffalse>
struct __conditional_type
{ typedef _Iftrue __type; };
template<typename _Iftrue, typename _Iffalse>
struct __conditional_type<false, _Iftrue, _Iffalse>
{ typedef _Iffalse __type; };
// Given an integral builtin type, return the corresponding unsigned type.
template<typename _Tp>
struct __add_unsigned
{
private:
typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
public:
typedef typename __if_type::__type __type;
};
template<>
struct __add_unsigned<char>
{ typedef unsigned char __type; };
template<>
struct __add_unsigned<signed char>
{ typedef unsigned char __type; };
template<>
struct __add_unsigned<short>
{ typedef unsigned short __type; };
template<>
struct __add_unsigned<int>
{ typedef unsigned int __type; };
template<>
struct __add_unsigned<long>
{ typedef unsigned long __type; };
template<>
struct __add_unsigned<long long>
{ typedef unsigned long long __type; };
// Declare but don't define.
template<>
struct __add_unsigned<bool>;
template<>
struct __add_unsigned<wchar_t>;
// Given an integral builtin type, return the corresponding signed type.
template<typename _Tp>
struct __remove_unsigned
{
private:
typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
public:
typedef typename __if_type::__type __type;
};
template<>
struct __remove_unsigned<char>
{ typedef signed char __type; };
template<>
struct __remove_unsigned<unsigned char>
{ typedef signed char __type; };
template<>
struct __remove_unsigned<unsigned short>
{ typedef short __type; };
template<>
struct __remove_unsigned<unsigned int>
{ typedef int __type; };
template<>
struct __remove_unsigned<unsigned long>
{ typedef long __type; };
template<>
struct __remove_unsigned<unsigned long long>
{ typedef long long __type; };
// Declare but don't define.
template<>
struct __remove_unsigned<bool>;
template<>
struct __remove_unsigned<wchar_t>;
// For use in string and vstring.
template<typename _Type>
inline bool
__is_null_pointer(_Type* __ptr)
{ return __ptr == 0; }
template<typename _Type>
inline bool
__is_null_pointer(_Type)
{ return false; }
#if __cplusplus >= 201103L
inline bool
__is_null_pointer(std::nullptr_t)
{ return true; }
#endif
// For complex and cmath
template<typename _Tp, bool = std::__is_integer<_Tp>::__value>
struct __promote
{ typedef double __type; };
// No nested __type member for non-integer non-floating point types,
// allows this type to be used for SFINAE to constrain overloads in
// <cmath> and <complex> to only the intended types.
template<typename _Tp>
struct __promote<_Tp, false>
{ };
template<>
struct __promote<long double>
{ typedef long double __type; };
template<>
struct __promote<double>
{ typedef double __type; };
template<>
struct __promote<float>
{ typedef float __type; };
template<typename _Tp, typename _Up,
typename _Tp2 = typename __promote<_Tp>::__type,
typename _Up2 = typename __promote<_Up>::__type>
struct __promote_2
{
typedef __typeof__(_Tp2() + _Up2()) __type;
};
template<typename _Tp, typename _Up, typename _Vp,
typename _Tp2 = typename __promote<_Tp>::__type,
typename _Up2 = typename __promote<_Up>::__type,
typename _Vp2 = typename __promote<_Vp>::__type>
struct __promote_3
{
typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type;
};
template<typename _Tp, typename _Up, typename _Vp, typename _Wp,
typename _Tp2 = typename __promote<_Tp>::__type,
typename _Up2 = typename __promote<_Up>::__type,
typename _Vp2 = typename __promote<_Vp>::__type,
typename _Wp2 = typename __promote<_Wp>::__type>
struct __promote_4
{
typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type;
};
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif
cpp_type_traits.h
c++config.h