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