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 <__iterator/access.h>
16#include <__memory/addressof.h>
17#include <__memory/voidify.h>
18#include <__type_traits/enable_if.h>
19#include <__type_traits/is_array.h>
20#include <__utility/declval.h>
21#include <__utility/forward.h>
22#include <__utility/move.h>
23#include <new>
24
25#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
26# pragma GCC system_header
27#endif
28
29_LIBCPP_PUSH_MACROS
30#include <__undef_macros>
31
32_LIBCPP_BEGIN_NAMESPACE_STD
33
34// construct_at
35
36#if _LIBCPP_STD_VER >= 20
37
38template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
39_LIBCPP_HIDE_FROM_ABI constexpr _Tp* construct_at(_Tp* __location, _Args&&... __args) {
40 _LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at");
41 return ::new (std::__voidify(*__location)) _Tp(std::forward<_Args>(__args)...);
42}
43
44#endif
45
46template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
47_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* __construct_at(_Tp* __location, _Args&&... __args) {
48#if _LIBCPP_STD_VER >= 20
49 return std::construct_at(__location, std::forward<_Args>(__args)...);
50#else
51 return _LIBCPP_ASSERT_NON_NULL(__location != nullptr, "null pointer given to construct_at"),
52 ::new (std::__voidify(*__location)) _Tp(std::forward<_Args>(__args)...);
53#endif
54}
55
56// destroy_at
57
58// The internal functions are available regardless of the language version (with the exception of the `__destroy_at`
59// taking an array).
60
61template <class _ForwardIterator>
62_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator __destroy(_ForwardIterator, _ForwardIterator);
63
64template <class _Tp, __enable_if_t<!is_array<_Tp>::value, int> = 0>
65_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy_at(_Tp* __loc) {
66 _LIBCPP_ASSERT_NON_NULL(__loc != nullptr, "null pointer given to destroy_at");
67 __loc->~_Tp();
68}
69
70#if _LIBCPP_STD_VER >= 20
71template <class _Tp, __enable_if_t<is_array<_Tp>::value, int> = 0>
72_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy_at(_Tp* __loc) {
73 _LIBCPP_ASSERT_NON_NULL(__loc != nullptr, "null pointer given to destroy_at");
74 std::__destroy(std::begin(*__loc), std::end(*__loc));
75}
76#endif
77
78template <class _ForwardIterator>
79_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator
80__destroy(_ForwardIterator __first, _ForwardIterator __last) {
81 for (; __first != __last; ++__first)
82 std::__destroy_at(std::addressof(*__first));
83 return __first;
84}
85
86template <class _BidirectionalIterator>
87_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _BidirectionalIterator
88__reverse_destroy(_BidirectionalIterator __first, _BidirectionalIterator __last) {
89 while (__last != __first) {
90 --__last;
91 std::__destroy_at(std::addressof(*__last));
92 }
93 return __last;
94}
95
96#if _LIBCPP_STD_VER >= 17
97
98template <class _Tp, enable_if_t<!is_array_v<_Tp>, int> = 0>
99_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* __loc) {
100 std::__destroy_at(__loc);
101}
102
103# if _LIBCPP_STD_VER >= 20
104template <class _Tp, enable_if_t<is_array_v<_Tp>, int> = 0>
105_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy_at(_Tp* __loc) {
106 std::__destroy_at(__loc);
107}
108# endif
109
110template <class _ForwardIterator>
111_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void destroy(_ForwardIterator __first, _ForwardIterator __last) {
112 (void)std::__destroy(std::move(__first), std::move(__last));
113}
114
115template <class _ForwardIterator, class _Size>
116_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _ForwardIterator destroy_n(_ForwardIterator __first, _Size __n) {
117 for (; __n > 0; (void)++__first, --__n)
118 std::__destroy_at(std::addressof(*__first));
119 return __first;
120}
121
122#endif // _LIBCPP_STD_VER >= 17
123
124_LIBCPP_END_NAMESPACE_STD
125
126_LIBCPP_POP_MACROS
127
128#endif // _LIBCPP___MEMORY_CONSTRUCT_AT_H
129