Hong Shin | cb845a5 | 2024-08-15 13:58:34 -0700 | [diff] [blame] | 1 | // Protocol Buffers - Google's data interchange format |
| 2 | // Copyright 2024 Google LLC. All rights reserved. |
| 3 | // |
| 4 | // Use of this source code is governed by a BSD-style |
| 5 | // license that can be found in the LICENSE file or at |
| 6 | // https://developers.google.com/open-source/licenses/bsd |
| 7 | |
| 8 | #ifndef GOOGLE_PROTOBUF_HPB_PTR_H__ |
| 9 | #define GOOGLE_PROTOBUF_HPB_PTR_H__ |
| 10 | |
| 11 | #include <memory> |
| 12 | #include <type_traits> |
| 13 | |
| 14 | class upb_Message; |
| 15 | class upb_Arena; |
| 16 | |
| 17 | namespace hpb { |
| 18 | |
| 19 | template <typename T> |
| 20 | using Proxy = std::conditional_t<std::is_const<T>::value, |
| 21 | typename std::remove_const_t<T>::CProxy, |
| 22 | typename T::Proxy>; |
| 23 | |
| 24 | // Provides convenient access to Proxy and CProxy message types. |
| 25 | // |
| 26 | // Using rebinding and handling of const, Ptr<Message> and Ptr<const Message> |
| 27 | // allows copying const with T* const and avoids using non-copyable Proxy types |
| 28 | // directly. |
| 29 | template <typename T> |
| 30 | class Ptr final { |
| 31 | public: |
| 32 | Ptr() = delete; |
| 33 | |
| 34 | // Implicit conversions |
| 35 | Ptr(T* m) : p_(m) {} // NOLINT |
| 36 | Ptr(const Proxy<T>* p) : p_(*p) {} // NOLINT |
| 37 | Ptr(Proxy<T> p) : p_(p) {} // NOLINT |
| 38 | Ptr(const Ptr& m) = default; |
| 39 | |
| 40 | Ptr& operator=(Ptr v) & { |
| 41 | Proxy<T>::Rebind(p_, v.p_); |
| 42 | return *this; |
| 43 | } |
| 44 | |
| 45 | Proxy<T> operator*() const { return p_; } |
| 46 | Proxy<T>* operator->() const { |
| 47 | return const_cast<Proxy<T>*>(std::addressof(p_)); |
| 48 | } |
| 49 | |
| 50 | #ifdef __clang__ |
| 51 | #pragma clang diagnostic push |
| 52 | #pragma clang diagnostic ignored "-Wclass-conversion" |
| 53 | #endif |
| 54 | template <typename U = T, std::enable_if_t<!std::is_const<U>::value, int> = 0> |
| 55 | operator Ptr<const T>() const { |
| 56 | Proxy<const T> p(p_); |
| 57 | return Ptr<const T>(&p); |
| 58 | } |
| 59 | #ifdef __clang__ |
| 60 | #pragma clang diagnostic pop |
| 61 | #endif |
| 62 | |
| 63 | private: |
| 64 | Ptr(upb_Message* msg, upb_Arena* arena) : p_(msg, arena) {} // NOLINT |
| 65 | |
| 66 | friend class Ptr<const T>; |
| 67 | friend typename T::Access; |
| 68 | |
| 69 | Proxy<T> p_; |
| 70 | }; |
| 71 | |
| 72 | // Suppress -Wctad-maybe-unsupported with our manual deduction guide |
| 73 | template <typename T> |
| 74 | Ptr(T* m) -> Ptr<T>; |
| 75 | |
| 76 | } // namespace hpb |
| 77 | |
| 78 | #endif // GOOGLE_PROTOBUF_HPB_PTR_H__ |