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Edit File: stl_construct.h

// nonstandard construct and destroy functions -*- C++ -*- // Copyright (C) 2001-2021 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/>. /* * * Copyright (c) 1994 * Hewlett-Packard Company * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Hewlett-Packard Company makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. * * * Copyright (c) 1996,1997 * Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Silicon Graphics makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. */ /** @file bits/stl_construct.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{memory} */ #ifndef _STL_CONSTRUCT_H #define _STL_CONSTRUCT_H 1 #include <new> #include <bits/move.h> #include <bits/stl_iterator_base_types.h> // for iterator_traits #include <bits/stl_iterator_base_funcs.h> // for advance /* This file provides the C++17 functions std::destroy_at, std::destroy, and * std::destroy_n, and the C++20 function std::construct_at. * It also provides std::_Construct, std::_Destroy,and std::_Destroy_n functions * which are defined in all standard modes and so can be used in C++98-14 code. * The _Destroy functions will dispatch to destroy_at during constant * evaluation, because calls to that function are intercepted by the compiler * to allow use in constant expressions. */ namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION #if __cplusplus >= 201703L template <typename _Tp> _GLIBCXX20_CONSTEXPR inline void destroy_at(_Tp* __location) { if constexpr (__cplusplus > 201703L && is_array_v<_Tp>) { for (auto& __x : *__location) std::destroy_at(std::__addressof(__x)); } else __location->~_Tp(); } #if __cplusplus >= 202002L template<typename _Tp, typename... _Args> constexpr auto construct_at(_Tp* __location, _Args&&... __args) noexcept(noexcept(::new((void*)0) _Tp(std::declval<_Args>()...))) -> decltype(::new((void*)0) _Tp(std::declval<_Args>()...)) { return ::new((void*)__location) _Tp(std::forward<_Args>(__args)...); } #endif // C++20 #endif// C++17 /** * Constructs an object in existing memory by invoking an allocated * object's constructor with an initializer. */ #if __cplusplus >= 201103L template<typename _Tp, typename... _Args> _GLIBCXX20_CONSTEXPR inline void _Construct(_Tp* __p, _Args&&... __args) { #if __cplusplus >= 202002L && __has_builtin(__builtin_is_constant_evaluated) if (__builtin_is_constant_evaluated()) { // Allow std::_Construct to be used in constant expressions. std::construct_at(__p, std::forward<_Args>(__args)...); return; } #endif ::new((void*)__p) _Tp(std::forward<_Args>(__args)...); } #else template<typename _T1, typename _T2> inline void _Construct(_T1* __p, const _T2& __value) { // _GLIBCXX_RESOLVE_LIB_DEFECTS // 402. wrong new expression in [some_]allocator::construct ::new(static_cast<void*>(__p)) _T1(__value); } #endif template<typename _T1> inline void _Construct_novalue(_T1* __p) { ::new((void*)__p) _T1; } template<typename _ForwardIterator> _GLIBCXX20_CONSTEXPR void _Destroy(_ForwardIterator __first, _ForwardIterator __last); /** * Destroy the object pointed to by a pointer type. */ template<typename _Tp> _GLIBCXX14_CONSTEXPR inline void _Destroy(_Tp* __pointer) { #if __cplusplus > 201703L std::destroy_at(__pointer); #else __pointer->~_Tp(); #endif } template<bool> struct _Destroy_aux { template<typename _ForwardIterator> static _GLIBCXX20_CONSTEXPR void __destroy(_ForwardIterator __first, _ForwardIterator __last) { for (; __first != __last; ++__first) std::_Destroy(std::__addressof(*__first)); } }; template<> struct _Destroy_aux<true> { template<typename _ForwardIterator> static void __destroy(_ForwardIterator, _ForwardIterator) { } }; /** * Destroy a range of objects. If the value_type of the object has * a trivial destructor, the compiler should optimize all of this * away, otherwise the objects' destructors must be invoked. */ template<typename _ForwardIterator> _GLIBCXX20_CONSTEXPR inline void _Destroy(_ForwardIterator __first, _ForwardIterator __last) { typedef typename iterator_traits<_ForwardIterator>::value_type _Value_type; #if __cplusplus >= 201103L // A deleted destructor is trivial, this ensures we reject such types: static_assert(is_destructible<_Value_type>::value, "value type is destructible"); #endif #if __cplusplus > 201703L && defined __cpp_lib_is_constant_evaluated if (std::is_constant_evaluated()) return _Destroy_aux<false>::__destroy(__first, __last); #endif std::_Destroy_aux<__has_trivial_destructor(_Value_type)>:: __destroy(__first, __last); } template<bool> struct _Destroy_n_aux { template<typename _ForwardIterator, typename _Size> static _GLIBCXX20_CONSTEXPR _ForwardIterator __destroy_n(_ForwardIterator __first, _Size __count) { for (; __count > 0; (void)++__first, --__count) std::_Destroy(std::__addressof(*__first)); return __first; } }; template<> struct _Destroy_n_aux<true> { template<typename _ForwardIterator, typename _Size> static _ForwardIterator __destroy_n(_ForwardIterator __first, _Size __count) { std::advance(__first, __count); return __first; } }; /** * Destroy a range of objects. If the value_type of the object has * a trivial destructor, the compiler should optimize all of this * away, otherwise the objects' destructors must be invoked. */ template<typename _ForwardIterator, typename _Size> _GLIBCXX20_CONSTEXPR inline _ForwardIterator _Destroy_n(_ForwardIterator __first, _Size __count) { typedef typename iterator_traits<_ForwardIterator>::value_type _Value_type; #if __cplusplus >= 201103L // A deleted destructor is trivial, this ensures we reject such types: static_assert(is_destructible<_Value_type>::value, "value type is destructible"); #endif #if __cplusplus > 201703L && defined __cpp_lib_is_constant_evaluated if (std::is_constant_evaluated()) return _Destroy_n_aux<false>::__destroy_n(__first, __count); #endif return std::_Destroy_n_aux<__has_trivial_destructor(_Value_type)>:: __destroy_n(__first, __count); } #if __cplusplus >= 201703L template <typename _ForwardIterator> _GLIBCXX20_CONSTEXPR inline void destroy(_ForwardIterator __first, _ForwardIterator __last) { std::_Destroy(__first, __last); } template <typename _ForwardIterator, typename _Size> _GLIBCXX20_CONSTEXPR inline _ForwardIterator destroy_n(_ForwardIterator __first, _Size __count) { return std::_Destroy_n(__first, __count); } #endif // C++17 _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #endif /* _STL_CONSTRUCT_H */