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___INOUT_PTR_H
11 #define _LIBCPP___INOUT_PTR_H
12
13 #include <__config>
14 #include <__memory/addressof.h>
15 #include <__memory/pointer_traits.h>
16 #include <__memory/shared_ptr.h>
17 #include <__memory/unique_ptr.h>
18 #include <__type_traits/is_pointer.h>
19 #include <__type_traits/is_same.h>
20 #include <__type_traits/is_specialization.h>
21 #include <__type_traits/is_void.h>
22 #include <__utility/forward.h>
23 #include <__utility/move.h>
24 #include <tuple>
25
26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
27 # pragma GCC system_header
28 #endif
29
30 _LIBCPP_PUSH_MACROS
31 #include <__undef_macros>
32
33 _LIBCPP_BEGIN_NAMESPACE_STD
34
35 #if _LIBCPP_STD_VER >= 23
36
37 template <class _Smart, class _Pointer, class... _Args>
38 class inout_ptr_t {
39 static_assert(!__is_specialization_v<_Smart, shared_ptr>, "std::shared_ptr<> is not supported with std::inout_ptr.");
40
41 public:
inout_ptr_t(_Smart & __smart,_Args...__args)42 _LIBCPP_HIDE_FROM_ABI explicit inout_ptr_t(_Smart& __smart, _Args... __args)
43 : __s_(__smart), __a_(std::forward<_Args>(__args)...), __p_([&__smart] {
44 if constexpr (is_pointer_v<_Smart>) {
45 return __smart;
46 } else {
47 return __smart.get();
48 }
49 }()) {
50 if constexpr (requires { __s_.release(); }) {
51 __s_.release();
52 } else {
53 __s_ = _Smart();
54 }
55 }
56
57 _LIBCPP_HIDE_FROM_ABI inout_ptr_t(const inout_ptr_t&) = delete;
58
~inout_ptr_t()59 _LIBCPP_HIDE_FROM_ABI ~inout_ptr_t() {
60 // LWG-3897 inout_ptr will not update raw pointer to null
61 if constexpr (!is_pointer_v<_Smart>) {
62 if (!__p_) {
63 return;
64 }
65 }
66
67 using _SmartPtr = __pointer_of_or_t<_Smart, _Pointer>;
68 if constexpr (is_pointer_v<_Smart>) {
69 std::apply([&](auto&&... __args) { __s_ = _Smart(static_cast<_SmartPtr>(__p_), std::forward<_Args>(__args)...); },
70 std::move(__a_));
71 } else if constexpr (__resettable_smart_pointer_with_args<_Smart, _Pointer, _Args...>) {
72 std::apply([&](auto&&... __args) { __s_.reset(static_cast<_SmartPtr>(__p_), std::forward<_Args>(__args)...); },
73 std::move(__a_));
74 } else {
75 static_assert(is_constructible_v<_Smart, _SmartPtr, _Args...>,
76 "The smart pointer must be constructible from arguments of types _Smart, _Pointer, _Args...");
77 std::apply([&](auto&&... __args) { __s_ = _Smart(static_cast<_SmartPtr>(__p_), std::forward<_Args>(__args)...); },
78 std::move(__a_));
79 }
80 }
81
82 _LIBCPP_HIDE_FROM_ABI operator _Pointer*() const noexcept { return std::addressof(const_cast<_Pointer&>(__p_)); }
83
84 _LIBCPP_HIDE_FROM_ABI operator void**() const noexcept
85 requires(!is_same_v<_Pointer, void*>)
86 {
87 static_assert(is_pointer_v<_Pointer>, "The conversion to void** requires _Pointer to be a raw pointer.");
88
89 return reinterpret_cast<void**>(static_cast<_Pointer*>(*this));
90 }
91
92 private:
93 _Smart& __s_;
94 tuple<_Args...> __a_;
95 _Pointer __p_;
96 };
97
98 template <class _Pointer = void, class _Smart, class... _Args>
inout_ptr(_Smart & __s,_Args &&...__args)99 _LIBCPP_HIDE_FROM_ABI auto inout_ptr(_Smart& __s, _Args&&... __args) {
100 using _Ptr = conditional_t<is_void_v<_Pointer>, __pointer_of_t<_Smart>, _Pointer>;
101 return std::inout_ptr_t<_Smart, _Ptr, _Args&&...>(__s, std::forward<_Args>(__args)...);
102 }
103
104 #endif // _LIBCPP_STD_VER >= 23
105
106 _LIBCPP_END_NAMESPACE_STD
107
108 _LIBCPP_POP_MACROS
109
110 #endif // _LIBCPP___INOUT_PTR_H
111