1// -*- C++ -*-
 2//===----------------------------------------------------------------------===//
 3//
 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 5// See https://llvm.org/LICENSE.txt for license information.
 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 7//
 8//===----------------------------------------------------------------------===//
 9
10#ifndef _LIBCPP___MEMORY_CONSTRUCT_AT_H
11#define _LIBCPP___MEMORY_CONSTRUCT_AT_H
12
13#include <__assert>
14#include <__config>
15#include <__memory/addressof.h>
16#include <__new/placement_new_delete.h>
17#include <__type_traits/enable_if.h>
18#include <__type_traits/is_array.h>
19#include <__utility/declval.h>
20#include <__utility/forward.h>
21
22#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
23#  pragma GCC system_header
24#endif
25
26_LIBCPP_PUSH_MACROS
27#include <__undef_macros>
28
29_LIBCPP_BEGIN_NAMESPACE_STD
30
31// construct_at
32
33#if _LIBCPP_STD_VER >= 20
34
35template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
36_LIBCPP_HIDE_FROM_ABI constexpr _Tp* construct_at(_Tp* __location, _Args&&... __args) {
37  _LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at");
38  return ::new (static_cast<void*>(__location)) _Tp(std::forward<_Args>(__args)...);
39}
40
41#endif
42
43template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
44_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* __construct_at(_Tp* __location, _Args&&... __args) {
45#if _LIBCPP_STD_VER >= 20
46  return std::construct_at(__location, std::forward<_Args>(__args)...);
47#else
48  return _LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at"),
49         ::new (static_cast<void*>(__location)) _Tp(std::forward<_Args>(__args)...);
50#endif
51}
52
53// destroy_at
54
55// The internal functions are available regardless of the language version (with the exception of the `__destroy_at`
56// taking an array).
57
58template <class _Tp, __enable_if_t<!is_array<_Tp>::value, int> = 0>
59_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy_at(_Tp* __loc) {
60  _LIBCPP_ASSERT_NON_NULL(__loc != nullptr, "null pointer given to destroy_at");
61  __loc->~_Tp();
62}
63
64#if _LIBCPP_STD_VER >= 20
65template <class _Tp, __enable_if_t<is_array<_Tp>::value, int> = 0>
66_LIBCPP_HIDE_FROM_ABI constexpr void __destroy_at(_Tp* __loc) {
67  _LIBCPP_ASSERT_NON_NULL(__loc != nullptr, "null pointer given to destroy_at");
68  for (auto&& __val : *__loc)
69    std::__destroy_at(std::addressof(__val));
70}
71#endif
72
73#if _LIBCPP_STD_VER >= 17
74
75template <class _Tp, enable_if_t<!is_array_v<_Tp>, int> = 0>
76_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* __loc) {
77  std::__destroy_at(__loc);
78}
79
80#  if _LIBCPP_STD_VER >= 20
81template <class _Tp, enable_if_t<is_array_v<_Tp>, int> = 0>
82_LIBCPP_HIDE_FROM_ABI constexpr void destroy_at(_Tp* __loc) {
83  std::__destroy_at(__loc);
84}
85#  endif
86
87#endif // _LIBCPP_STD_VER >= 17
88
89_LIBCPP_END_NAMESPACE_STD
90
91_LIBCPP_POP_MACROS
92
93#endif // _LIBCPP___MEMORY_CONSTRUCT_AT_H