Struct Weak

pub struct Weak<T: ?Sized, Owner: ?Sized = dyn Destruct + Send + Sync> { /* private fields */ }

A projecting version of Weak which allows owning a containing struct but referencing a field.

Implementations

impl<'a, T: 'a + Send + Sync> Weak<T, dyn Destruct + Send + Sync + 'a>

pub fn new() -> Self

Constructs a new Weak<T> with erased owner.

impl<T, Owner> Weak<T, Owner>

pub fn new_owner() -> Self

Constructs a new Weak<T, T> with typed owner.

impl<'a, T: ?Sized, Owner: 'a + Send + Sync> Weak<T, Owner>

pub fn erase_owner(this: Self) -> Weak<T, dyn Destruct + Send + Sync + 'a>

Erases the owning type so that projected Weak<T> can be used uniformly.

impl<T: ?Sized, Owner: ?Sized> Weak<T, Owner>

pub fn as_ptr(&self) -> *const T

Returns a raw pointer to the object T pointed to by this Weak<T>.

The pointer is valid only if there are some strong references. The pointer may be dangling, unaligned, or even null otherwise.

pub fn upgrade(&self) -> Option<Arc<T, Owner>>

Attempts to upgrade the Weak pointer to Arc<T>.

Returns None if no strong references exist.

pub fn owner(this: &Self) -> Weak<Owner>

Gets a reference to the owning allocation.

pub fn into_owner(this: Self) -> Weak<Owner>

Consumes this projected field, returning the owning allocation.

pub fn project<U: Sized>( this: Self, projection: impl FnOnce(&T) -> &U, ) -> Weak<U, Owner>

Projects this allocation to a field.

If no strong references exist, the closure will not be called.

pub fn ptr_eq(lhs: &Self, rhs: &Self) -> bool

Returns true if the two Weaks point to the same field in the same allocated object, or if both don’t point to anything (i.e. because they were created with Weak::new()).

See ptr::eq for the caveats when comparing dyn Trait pointers, which this does when the owner type is erased.

impl<T: ?Sized, Owner: ?Sized> Weak<T, Owner>

pub fn unsize<U: ?Sized, F>( this: Self, with: Coercion<T, U, F>, ) -> Weak<U, Owner>

where T: Sized, F: FnOnce(*const T) -> *const U,

Available on crate feature unsize only.

Convert this pointer with an unsizing coercion (e.g. from T to dyn Trait or [T; N] to [T]).

pub fn unsize_owner<Pwner: ?Sized, F>( this: Self, with: Coercion<Owner, Pwner, F>, ) -> Weak<T, Pwner>

where Owner: Sized, F: FnOnce(*const Owner) -> *const Pwner,

Available on crate feature unsize only.

Convert this pointer with an unsizing coercion of the owner (e.g. from T to dyn Trait or [T; N] to [T]).

Trait Implementations

impl<T: ?Sized, Owner: ?Sized> Clone for Weak<T, Owner>

fn clone(&self) -> Self

Returns a duplicate of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T, U: ?Sized, Owner: ?Sized> CoerciblePtr<U> for Weak<T, Owner>

Available on crate feature unsize only.

type Pointee = T

The type we point to. This influences which kinds of unsizing are possible.

type Output = Weak<U, Owner>

The output type when unsizing the pointee to U.

fn as_sized_ptr(&mut self) -> *mut Self::Pointee

Get the raw inner pointer.

unsafe fn replace_ptr(self, ptr: *mut U) -> Self::Output

Replace the container inner pointer with an unsized version.

impl<T, Owner: ?Sized> Debug for Weak<T, Owner>

where T: Debug + ?Sized,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T, Owner> Default for Weak<T, Owner>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, T: 'a> Default for Weak<T, dyn Destruct + 'a>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, T: 'a> Default for Weak<T, dyn Destruct + Send + 'a>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, T: 'a> Default for Weak<T, dyn Destruct + Send + Sync + 'a>

fn default() -> Self

Returns the “default value” for a type.

impl<T> From<Weak<T>> for Weak<T, T>

fn from(owner: Weak<T>) -> Self

Converts to this type from the input type.

impl<T: ?Sized, Owner: ?Sized> From<Weak<T, Owner>> for Weak<Owner>

fn from(this: Weak<T, Owner>) -> Self

Converts to this type from the input type.

impl<'a, T: ?Sized, Owner: 'a> From<Weak<T, Owner>> for Weak<T, dyn Destruct + 'a>

fn from(this: Weak<T, Owner>) -> Self

Converts to this type from the input type.

impl<'a, T: ?Sized, Owner: 'a + Send> From<Weak<T, Owner>> for Weak<T, dyn Destruct + Send + 'a>

fn from(this: Weak<T, Owner>) -> Self

Converts to this type from the input type.

impl<'a, T: ?Sized, Owner: 'a + Send + Sync> From<Weak<T, Owner>> for Weak<T, dyn Destruct + Send + Sync + 'a>

fn from(this: Weak<T, Owner>) -> Self

Converts to this type from the input type.

impl<T: ?Sized, Owner: ?Sized> Send for Weak<T, Owner>

where for<'a> &'a T: Send, Weak<T>: Send,

impl<T: ?Sized, Owner: ?Sized> Sync for Weak<T, Owner>

where for<'a> &'a T: Sync, Weak<T>: Sync,

impl<T: ?Sized, Owner: ?Sized> UnwindSafe for Weak<T, Owner>

where for<'a> &'a T: UnwindSafe, Weak<Owner>: UnwindSafe,

Available on crate feature std only.