template <typename T>class UniquePtr
Defined at line 920 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
A unique-pointer-like smart pointer type for holding objects that
correctly and safely deletes them, whether or not the objects owned by
protobuf `Arena`s. `UniquePtr` is used to hold either a newly created
object or a message released from a parent container.
In spirit, an `Arena::UniquePtr
<T
>` is akin to
`std::variant
<std
::unique_ptr
<T
>, Arena::Ptr
<T
>>`. It might semantically
contain either of those types, it can be constructed from them, and you can
extract them out as needed.
To create an `UniquePtr`, use the helper functions in `Arena` or release a
message from a parent using one of the release functions in
message_movers.h.
If using heap, this smart pointer will own its object and destroy it as
needed.
`UniquePtr` provides a similar interface to `std::unique_ptr` except that
it also provides access to the message's owning `Arena`, explicitly removes
the `reset(T*)` function (though it leaves `reset()` and `reset(nullptr)`),
and makes all constructors except the move-constructor private. Instead of
`reset(T*)` or a constructor, you should use move assignment and the
`MakeUnique`/`UnsafeWrapUniquePtr` functions.
Example Usage:
Arena* arena_ptr = ...;
UniquePtr
<MyMessage
> parent = Arena::MakeUnique
<MyMessage
>(arena_ptr);
...
UniquePtr
<ChildMessage
> ptr =
google::protobuf::ReleaseMessageField
<
"child_field">(parent);
...
ptr.reset(); // Will delete ChildMessage ptr if arena_ptr was nullptr.
CHECK(ptr == nullptr);
...
ModifyChildMessage(ptr.get());
ConsumeChildMessage(std::move(ptr));
Public Methods
void UniquePtr<T> ()Public Constructors
Defined at line 929 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void UniquePtr<T> (std::nullptr_t )NOLINTNEXTLINE(google-explicit-constructor)
Defined at line 931 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void UniquePtr<T> (std::unique_ptr<T> heap_owned)Allow implicit conversion from `std::unique_ptr` with
`std::default_delete`.
This is always safe since `UniquePtr` can safely hold heap-allocated
pointers.
NOLINTNEXTLINE(google-explicit-constructor)
Defined at line 938 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void UniquePtr<T> (Ptr<T> arena_owned)Allow implicit conversion from `Ptr
<T
>`.
This is always safe since `Ptr` is statically known to be owned by an
arena. There is no "unique" ownership on it.
NOLINTNEXTLINE(google-explicit-constructor)
Defined at line 945 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void ~UniquePtr<T> ()Defined at line 948 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void UniquePtr<T> (UniquePtr<T> && rhs)Defined at line 950 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
template <typename U, typename = std::enable_if_t<std::is_convertible_v<U*, T*>>>
void UniquePtr<T> (UniquePtr<U> && rhs)NOLINTNEXTLINE(google-explicit-constructor)
Defined at line 954 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void UniquePtr<T> (T * ptr)Use Arena::UnsafeWrapUniquePtr or Arena::MakeUnique
Defined at line 957 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
UniquePtr<T> & operator= (UniquePtr<T> && rhs)Defined at line 959 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
UniquePtr<T> & operator= (std::nullptr_t )Defined at line 960 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
template <typename U, typename = std::enable_if_t<std::is_convertible_v<U*, T*>>>
UniquePtr<T> & operator= (UniquePtr<U> && rhs)Defined at line 966 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void UniquePtr<T> (const UniquePtr<T> & rhs)Delete the copy ctor and copy assignment operator.
Defined at line 972 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
UniquePtr<T> & operator= (const UniquePtr<T> & rhs)Defined at line 973 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
absl::optional<std::unique_ptr<T>> try_heap_release ()If heap allocated transfer ownership of the pointer to the caller, clearing
the `UniquePtr` instance.
Otherwise, return `absl::nullopt` and have no effect.
Defined at line 978 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
absl::optional<Ptr<T>> try_as_arena_ptr ()If it contains an arena allocated object, return a `Ptr` to the caller.
Otherwise, return `absl::nullopt`.
This function has does not modify the `UniquePtr`.
Defined at line 988 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void swap (UniquePtr<T> & other)Defined at line 997 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void reset ()reset() the pointed to object to nullptr.
Defined at line 1001 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void reset (std::nullptr_t )Defined at line 1002 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
void reset (T * )Defined at line 1005 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
pointer get ()Defined at line 1007 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
pointer operator-> ()Defined at line 1010 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
element_type & operator* ()Defined at line 1013 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
bool operator bool ()Defined at line 1017 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
Arena * GetOwningArena ()Return a pointer to the Arena pointer that owns the pointed to message.
Defined at line 1020 of file ../../third_party/protobuf/src/src/google/protobuf/arena.h
Friends
template <typename U>class UniquePtrtemplate <typename T>class Arenatemplate <typename H>H UniquePtr (H h, const UniquePtr<T> & u)template <typename Sink>void UniquePtr (Sink & sink, const UniquePtr<T> & ptr)template <typename T>void UniquePtr (UniquePtr<T> & aUniquePtr<T> & b)