Struct scale_info::prelude::rc::UniqueRc

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pub struct UniqueRc<T, A = Global>
where A: Allocator, T: ?Sized,
{ /* private fields */ }
🔬This is a nightly-only experimental API. (unique_rc_arc)
Expand description

A uniquely owned Rc.

This represents an Rc that is known to be uniquely owned – that is, have exactly one strong reference. Multiple weak pointers can be created, but attempts to upgrade those to strong references will fail unless the UniqueRc they point to has been converted into a regular Rc.

Because they are uniquely owned, the contents of a UniqueRc can be freely mutated. A common use case is to have an object be mutable during its initialization phase but then have it become immutable and converted to a normal Rc.

This can be used as a flexible way to create cyclic data structures, as in the example below.

#![feature(unique_rc_arc)]
use std::rc::{Rc, Weak, UniqueRc};

struct Gadget {
    #[allow(dead_code)]
    me: Weak<Gadget>,
}

fn create_gadget() -> Option<Rc<Gadget>> {
    let mut rc = UniqueRc::new(Gadget {
        me: Weak::new(),
    });
    rc.me = UniqueRc::downgrade(&rc);
    Some(UniqueRc::into_rc(rc))
}

create_gadget().unwrap();

An advantage of using UniqueRc over Rc::new_cyclic to build cyclic data structures is that Rc::new_cyclic’s data_fn parameter cannot be async or return a Result. As shown in the previous example, UniqueRc allows for more flexibility in the construction of cyclic data, including fallible or async constructors.

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impl<T> UniqueRc<T>

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pub fn new(value: T) -> UniqueRc<T>

🔬This is a nightly-only experimental API. (unique_rc_arc)

Creates a new UniqueRc.

Weak references to this UniqueRc can be created with UniqueRc::downgrade. Upgrading these weak references will fail before the UniqueRc has been converted into an Rc. After converting the UniqueRc into an Rc, any weak references created beforehand will point to the new Rc.

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impl<T, A> UniqueRc<T, A>
where A: Allocator,

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pub fn new_in(value: T, alloc: A) -> UniqueRc<T, A>

🔬This is a nightly-only experimental API. (unique_rc_arc)

Creates a new UniqueRc in the provided allocator.

Weak references to this UniqueRc can be created with UniqueRc::downgrade. Upgrading these weak references will fail before the UniqueRc has been converted into an Rc. After converting the UniqueRc into an Rc, any weak references created beforehand will point to the new Rc.

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impl<T, A> UniqueRc<T, A>
where A: Allocator, T: ?Sized,

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pub fn into_rc(this: UniqueRc<T, A>) -> Rc<T, A>

🔬This is a nightly-only experimental API. (unique_rc_arc)

Converts the UniqueRc into a regular Rc.

This consumes the UniqueRc and returns a regular Rc that contains the value that is passed to into_rc.

Any weak references created before this method is called can now be upgraded to strong references.

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impl<T, A> UniqueRc<T, A>
where A: Allocator + Clone, T: ?Sized,

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pub fn downgrade(this: &UniqueRc<T, A>) -> Weak<T, A>

🔬This is a nightly-only experimental API. (unique_rc_arc)

Creates a new weak reference to the UniqueRc.

Attempting to upgrade this weak reference will fail before the UniqueRc has been converted to a Rc using UniqueRc::into_rc.

Trait Implementations§

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impl<T, A> Debug for UniqueRc<T, A>
where T: Debug + ?Sized, A: Debug + Allocator,

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

Formats the value using the given formatter. Read more
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impl<T, A> Deref for UniqueRc<T, A>
where A: Allocator, T: ?Sized,

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &T

Dereferences the value.
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impl<T, A> DerefMut for UniqueRc<T, A>
where A: Allocator, T: ?Sized,

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fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.
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impl<T, A> Drop for UniqueRc<T, A>
where A: Allocator, T: ?Sized,

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<T, U, A> CoerceUnsized<UniqueRc<U, A>> for UniqueRc<T, A>
where T: Unsize<U> + ?Sized, A: Allocator, U: ?Sized,

Auto Trait Implementations§

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impl<T, A> Freeze for UniqueRc<T, A>
where A: Freeze, T: ?Sized,

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impl<T, A = Global> !RefUnwindSafe for UniqueRc<T, A>

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impl<T, A = Global> !Send for UniqueRc<T, A>

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impl<T, A = Global> !Sync for UniqueRc<T, A>

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impl<T, A> Unpin for UniqueRc<T, A>
where A: Unpin, T: Unpin + ?Sized,

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impl<T, A = Global> !UnwindSafe for UniqueRc<T, A>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> Conv for T

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fn conv<T>(self) -> T
where Self: Into<T>,

Converts self into T using Into<T>. Read more
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impl<T> FmtForward for T

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fn fmt_binary(self) -> FmtBinary<Self>
where Self: Binary,

Causes self to use its Binary implementation when Debug-formatted.
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fn fmt_display(self) -> FmtDisplay<Self>
where Self: Display,

Causes self to use its Display implementation when Debug-formatted.
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fn fmt_lower_exp(self) -> FmtLowerExp<Self>
where Self: LowerExp,

Causes self to use its LowerExp implementation when Debug-formatted.
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fn fmt_lower_hex(self) -> FmtLowerHex<Self>
where Self: LowerHex,

Causes self to use its LowerHex implementation when Debug-formatted.
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fn fmt_octal(self) -> FmtOctal<Self>
where Self: Octal,

Causes self to use its Octal implementation when Debug-formatted.
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fn fmt_pointer(self) -> FmtPointer<Self>
where Self: Pointer,

Causes self to use its Pointer implementation when Debug-formatted.
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fn fmt_upper_exp(self) -> FmtUpperExp<Self>
where Self: UpperExp,

Causes self to use its UpperExp implementation when Debug-formatted.
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fn fmt_upper_hex(self) -> FmtUpperHex<Self>
where Self: UpperHex,

Causes self to use its UpperHex implementation when Debug-formatted.
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fn fmt_list(self) -> FmtList<Self>
where &'a Self: for<'a> IntoIterator,

Formats each item in a sequence. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> Pipe for T
where T: ?Sized,

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fn pipe<R>(self, func: impl FnOnce(Self) -> R) -> R
where Self: Sized,

Pipes by value. This is generally the method you want to use. Read more
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fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> R
where R: 'a,

Borrows self and passes that borrow into the pipe function. Read more
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fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> R
where R: 'a,

Mutably borrows self and passes that borrow into the pipe function. Read more
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fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> R
where Self: Borrow<B>, B: 'a + ?Sized, R: 'a,

Borrows self, then passes self.borrow() into the pipe function. Read more
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fn pipe_borrow_mut<'a, B, R>( &'a mut self, func: impl FnOnce(&'a mut B) -> R, ) -> R
where Self: BorrowMut<B>, B: 'a + ?Sized, R: 'a,

Mutably borrows self, then passes self.borrow_mut() into the pipe function. Read more
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fn pipe_as_ref<'a, U, R>(&'a self, func: impl FnOnce(&'a U) -> R) -> R
where Self: AsRef<U>, U: 'a + ?Sized, R: 'a,

Borrows self, then passes self.as_ref() into the pipe function.
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fn pipe_as_mut<'a, U, R>(&'a mut self, func: impl FnOnce(&'a mut U) -> R) -> R
where Self: AsMut<U>, U: 'a + ?Sized, R: 'a,

Mutably borrows self, then passes self.as_mut() into the pipe function.
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fn pipe_deref<'a, T, R>(&'a self, func: impl FnOnce(&'a T) -> R) -> R
where Self: Deref<Target = T>, T: 'a + ?Sized, R: 'a,

Borrows self, then passes self.deref() into the pipe function.
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fn pipe_deref_mut<'a, T, R>( &'a mut self, func: impl FnOnce(&'a mut T) -> R, ) -> R
where Self: DerefMut<Target = T> + Deref, T: 'a + ?Sized, R: 'a,

Mutably borrows self, then passes self.deref_mut() into the pipe function.
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impl<T> Tap for T

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fn tap(self, func: impl FnOnce(&Self)) -> Self

Immutable access to a value. Read more
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fn tap_mut(self, func: impl FnOnce(&mut Self)) -> Self

Mutable access to a value. Read more
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fn tap_borrow<B>(self, func: impl FnOnce(&B)) -> Self
where Self: Borrow<B>, B: ?Sized,

Immutable access to the Borrow<B> of a value. Read more
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fn tap_borrow_mut<B>(self, func: impl FnOnce(&mut B)) -> Self
where Self: BorrowMut<B>, B: ?Sized,

Mutable access to the BorrowMut<B> of a value. Read more
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fn tap_ref<R>(self, func: impl FnOnce(&R)) -> Self
where Self: AsRef<R>, R: ?Sized,

Immutable access to the AsRef<R> view of a value. Read more
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fn tap_ref_mut<R>(self, func: impl FnOnce(&mut R)) -> Self
where Self: AsMut<R>, R: ?Sized,

Mutable access to the AsMut<R> view of a value. Read more
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fn tap_deref<T>(self, func: impl FnOnce(&T)) -> Self
where Self: Deref<Target = T>, T: ?Sized,

Immutable access to the Deref::Target of a value. Read more
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fn tap_deref_mut<T>(self, func: impl FnOnce(&mut T)) -> Self
where Self: DerefMut<Target = T> + Deref, T: ?Sized,

Mutable access to the Deref::Target of a value. Read more
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fn tap_dbg(self, func: impl FnOnce(&Self)) -> Self

Calls .tap() only in debug builds, and is erased in release builds.
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fn tap_mut_dbg(self, func: impl FnOnce(&mut Self)) -> Self

Calls .tap_mut() only in debug builds, and is erased in release builds.
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fn tap_borrow_dbg<B>(self, func: impl FnOnce(&B)) -> Self
where Self: Borrow<B>, B: ?Sized,

Calls .tap_borrow() only in debug builds, and is erased in release builds.
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fn tap_borrow_mut_dbg<B>(self, func: impl FnOnce(&mut B)) -> Self
where Self: BorrowMut<B>, B: ?Sized,

Calls .tap_borrow_mut() only in debug builds, and is erased in release builds.
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fn tap_ref_dbg<R>(self, func: impl FnOnce(&R)) -> Self
where Self: AsRef<R>, R: ?Sized,

Calls .tap_ref() only in debug builds, and is erased in release builds.
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fn tap_ref_mut_dbg<R>(self, func: impl FnOnce(&mut R)) -> Self
where Self: AsMut<R>, R: ?Sized,

Calls .tap_ref_mut() only in debug builds, and is erased in release builds.
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fn tap_deref_dbg<T>(self, func: impl FnOnce(&T)) -> Self
where Self: Deref<Target = T>, T: ?Sized,

Calls .tap_deref() only in debug builds, and is erased in release builds.
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fn tap_deref_mut_dbg<T>(self, func: impl FnOnce(&mut T)) -> Self
where Self: DerefMut<Target = T> + Deref, T: ?Sized,

Calls .tap_deref_mut() only in debug builds, and is erased in release builds.
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impl<T> TryConv for T

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fn try_conv<T>(self) -> Result<T, Self::Error>
where Self: TryInto<T>,

Attempts to convert self into T using TryInto<T>. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> JsonSchemaMaybe for T