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f332455dd9
This patch separates the destroy algorithms from the primitive construct_at and destroy_at operations, which are conceptually not algorithms. This makes it easier to start using these destroy algorithms from upcoming relocation facilities. As part of this, it also implements `std::destroy_at` for arrays without relying on the `std::destroy` algorithm, which is conceptually a higher-level facility.
97 lines
3.1 KiB
C++
97 lines
3.1 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___MEMORY_CONSTRUCT_AT_H
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#define _LIBCPP___MEMORY_CONSTRUCT_AT_H
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#include <__assert>
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#include <__config>
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#include <__iterator/access.h>
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#include <__memory/addressof.h>
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#include <__new/placement_new_delete.h>
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#include <__type_traits/enable_if.h>
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#include <__type_traits/is_array.h>
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#include <__utility/declval.h>
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#include <__utility/forward.h>
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#include <__utility/move.h>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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// construct_at
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#if _LIBCPP_STD_VER >= 20
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template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
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_LIBCPP_HIDE_FROM_ABI constexpr _Tp* construct_at(_Tp* __location, _Args&&... __args) {
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_LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at");
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return ::new (static_cast<void*>(__location)) _Tp(std::forward<_Args>(__args)...);
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}
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#endif
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template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* __construct_at(_Tp* __location, _Args&&... __args) {
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#if _LIBCPP_STD_VER >= 20
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return std::construct_at(__location, std::forward<_Args>(__args)...);
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#else
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return _LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at"),
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::new (static_cast<void*>(__location)) _Tp(std::forward<_Args>(__args)...);
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#endif
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}
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// destroy_at
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// The internal functions are available regardless of the language version (with the exception of the `__destroy_at`
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// taking an array).
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template <class _Tp, __enable_if_t<!is_array<_Tp>::value, int> = 0>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy_at(_Tp* __loc) {
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_LIBCPP_ASSERT_NON_NULL(__loc != nullptr, "null pointer given to destroy_at");
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__loc->~_Tp();
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}
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#if _LIBCPP_STD_VER >= 20
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template <class _Tp, __enable_if_t<is_array<_Tp>::value, int> = 0>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy_at(_Tp* __loc) {
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_LIBCPP_ASSERT_NON_NULL(__loc != nullptr, "null pointer given to destroy_at");
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auto const __end = std::end(*__loc);
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for (auto __it = std::begin(*__loc); __it != __end; ++__it)
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std::__destroy_at(__it);
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}
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#endif
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#if _LIBCPP_STD_VER >= 17
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template <class _Tp, enable_if_t<!is_array_v<_Tp>, int> = 0>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* __loc) {
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std::__destroy_at(__loc);
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}
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# if _LIBCPP_STD_VER >= 20
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template <class _Tp, enable_if_t<is_array_v<_Tp>, int> = 0>
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* __loc) {
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std::__destroy_at(__loc);
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}
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# endif
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#endif // _LIBCPP_STD_VER >= 17
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___MEMORY_CONSTRUCT_AT_H
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