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Editing: type_traits.h
// -*- C++ -*- // Copyright (C) 2005-2022 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> extern "C++" { 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> _GLIBCXX_CONSTEXPR inline bool __is_null_pointer(_Type* __ptr) { return __ptr == 0; } template<typename _Type> _GLIBCXX_CONSTEXPR inline bool __is_null_pointer(_Type) { return false; } #if __cplusplus >= 201103L constexpr bool __is_null_pointer(std::nullptr_t) { return true; } #endif // For arithmetic promotions in <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; }; #if __cpp_fold_expressions template<typename... _Tp> using __promoted_t = decltype((typename __promote<_Tp>::__type(0) + ...)); // Deducing the promoted type is done by __promoted_t<_Tp...>, // then __promote is used to provide the nested __type member. template<typename _Tp, typename _Up> using __promote_2 = __promote<__promoted_t<_Tp, _Up>>; template<typename _Tp, typename _Up, typename _Vp> using __promote_3 = __promote<__promoted_t<_Tp, _Up, _Vp>>; template<typename _Tp, typename _Up, typename _Vp, typename _Wp> using __promote_4 = __promote<__promoted_t<_Tp, _Up, _Vp, _Wp>>; #else 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; }; #endif _GLIBCXX_END_NAMESPACE_VERSION } // namespace } // extern "C++" #endif
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