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 36 template <class _Smart, class _Pointer, class... _Args> 37 class _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 40 public: 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 91 private: 92 _Smart& __s_; 93 tuple<_Args...> __a_; 94 _Pointer __p_; 95 }; 96 97 template <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