111 lines · c
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-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___INOUT_PTR_H11#define _LIBCPP___INOUT_PTR_H12 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_header28#endif29 30_LIBCPP_PUSH_MACROS31#include <__undef_macros>32 33_LIBCPP_BEGIN_NAMESPACE_STD34 35#if _LIBCPP_STD_VER >= 2336 37template <class _Smart, class _Pointer, class... _Args>38class inout_ptr_t {39 static_assert(!__is_specialization_v<_Smart, shared_ptr>, "std::shared_ptr<> is not supported with std::inout_ptr.");40 41public: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 59 _LIBCPP_HIDE_FROM_ABI ~inout_ptr_t() {60 // LWG-3897 inout_ptr will not update raw pointer to null61 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 noexcept85 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 92private:93 _Smart& __s_;94 tuple<_Args...> __a_;95 _Pointer __p_;96};97 98template <class _Pointer = void, class _Smart, class... _Args>99[[nodiscard]] _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 >= 23105 106_LIBCPP_END_NAMESPACE_STD107 108_LIBCPP_POP_MACROS109 110#endif // _LIBCPP___INOUT_PTR_H111