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