pub struct OwningRef<O, T: ?Sized> {
    owner: O,
    reference: *const T,
}
Expand description

An owning reference.

This wraps an owner O and a reference &T pointing at something reachable from O::Target while keeping the ability to move self around.

The owner is usually a pointer that points at some base type.

For more details and examples, see the module and method docs.

Fields§

§owner: O§reference: *const T

Implementations§

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impl<O, T: ?Sized> OwningRef<O, T>

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pub fn new(o: O) -> Selfwhere O: StableAddress + Deref<Target = T>,

Creates a new owning reference from an owner initialized to the direct dereference of it.

Example
use rustc_data_structures::owning_ref::OwningRef;

fn main() {
    let owning_ref = OwningRef::new(Box::new(42));
    assert_eq!(*owning_ref, 42);
}
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pub unsafe fn new_assert_stable_address(o: O) -> Selfwhere O: Deref<Target = T>,

Like new, but doesn’t require O to implement the StableAddress trait. Instead, the caller is responsible to make the same promises as implementing the trait.

This is useful for cases where coherence rules prevents implementing the trait without adding a dependency to this crate in a third-party library.

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pub fn map<F, U: ?Sized>(self, f: F) -> OwningRef<O, U>where O: StableAddress, F: FnOnce(&T) -> &U,

Converts self into a new owning reference that points at something reachable from the previous one.

This can be a reference to a field of U, something reachable from a field of U, or even something unrelated with a 'static lifetime.

Example
use rustc_data_structures::owning_ref::OwningRef;

fn main() {
    let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));

    // create an owning reference that points at the
    // third element of the array.
    let owning_ref = owning_ref.map(|array| &array[2]);
    assert_eq!(*owning_ref, 3);
}
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pub fn try_map<F, U: ?Sized, E>(self, f: F) -> Result<OwningRef<O, U>, E>where O: StableAddress, F: FnOnce(&T) -> Result<&U, E>,

Tries to convert self into a new owning reference that points at something reachable from the previous one.

This can be a reference to a field of U, something reachable from a field of U, or even something unrelated with a 'static lifetime.

Example
use rustc_data_structures::owning_ref::OwningRef;

fn main() {
    let owning_ref = OwningRef::new(Box::new([1, 2, 3, 4]));

    // create an owning reference that points at the
    // third element of the array.
    let owning_ref = owning_ref.try_map(|array| {
        if array[2] == 3 { Ok(&array[2]) } else { Err(()) }
    });
    assert_eq!(*owning_ref.unwrap(), 3);
}
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pub unsafe fn map_owner<F, P>(self, f: F) -> OwningRef<P, T>where O: StableAddress, P: StableAddress, F: FnOnce(O) -> P,

Converts self into a new owning reference with a different owner type.

The new owner type needs to still contain the original owner in some way so that the reference into it remains valid. This function is marked unsafe because the user needs to manually uphold this guarantee.

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pub fn map_owner_box(self) -> OwningRef<Box<O>, T>

Converts self into a new owning reference where the owner is wrapped in an additional Box<O>.

This can be used to safely erase the owner of any OwningRef<O, T> to an OwningRef<Box<Erased>, T>.

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pub fn erase_owner<'a>(self) -> OwningRef<O::Erased, T>where O: IntoErased<'a>,

Erases the concrete base type of the owner with a trait object.

This allows mixing of owned references with different owner base types.

Example
use rustc_data_structures::owning_ref::{OwningRef, Erased};

fn main() {
    // N.B., using the concrete types here for explicitness.
    // For less verbose code type aliases like `BoxRef` are provided.

    let owning_ref_a: OwningRef<Box<[i32; 4]>, [i32; 4]>
        = OwningRef::new(Box::new([1, 2, 3, 4]));

    let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, Vec<(i32, bool)>>
        = OwningRef::new(Box::new(vec![(0, false), (1, true)]));

    let owning_ref_a: OwningRef<Box<[i32; 4]>, i32>
        = owning_ref_a.map(|a| &a[0]);

    let owning_ref_b: OwningRef<Box<Vec<(i32, bool)>>, i32>
        = owning_ref_b.map(|a| &a[1].0);

    let owning_refs: [OwningRef<Box<dyn Erased>, i32>; 2]
        = [owning_ref_a.erase_owner(), owning_ref_b.erase_owner()];

    assert_eq!(*owning_refs[0], 1);
    assert_eq!(*owning_refs[1], 1);
}
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pub fn erase_send_owner<'a>(self) -> OwningRef<O::Erased, T>where O: IntoErasedSend<'a>,

Erases the concrete base type of the owner with a trait object which implements Send.

This allows mixing of owned references with different owner base types.

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pub fn erase_send_sync_owner<'a>(self) -> OwningRef<O::Erased, T>where O: IntoErasedSendSync<'a>,

Erases the concrete base type of the owner with a trait object which implements Send and Sync.

This allows mixing of owned references with different owner base types.

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pub fn owner(&self) -> &O

A getter for the underlying owner.

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pub fn into_inner(self) -> O

Discards the reference and retrieves the owner.

Trait Implementations§

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impl<O, T: ?Sized> AsRef<T> for OwningRef<O, T>

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fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.
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impl<O, T: ?Sized> Borrow<T> for OwningRef<O, T>

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<O, T: ?Sized> Clone for OwningRef<O, T>where O: CloneStableAddress,

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<O, T> Debug for OwningRef<O, T>where O: Debug, T: Debug + ?Sized,

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

Formats the value using the given formatter. Read more
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impl<O, T: ?Sized> Deref for OwningRef<O, T>

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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<O, T: ?Sized> From<O> for OwningRef<O, T>where O: StableAddress + Deref<Target = T>,

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fn from(owner: O) -> Self

Converts to this type from the input type.
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impl<O, T: ?Sized> From<OwningRefMut<O, T>> for OwningRef<O, T>where O: StableAddress + DerefMut<Target = T>,

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fn from(other: OwningRefMut<O, T>) -> Self

Converts to this type from the input type.
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impl<O, T> Hash for OwningRef<O, T>where T: Hash + ?Sized,

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fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl<O, T> Ord for OwningRef<O, T>where T: Ord + ?Sized,

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fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other. Read more
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fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more
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fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more
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fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval. Read more
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impl<O, T> PartialEq<OwningRef<O, T>> for OwningRef<O, T>where T: PartialEq + ?Sized,

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fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<O, T> PartialOrd<OwningRef<O, T>> for OwningRef<O, T>where T: PartialOrd + ?Sized,

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fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists. Read more
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fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
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fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
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fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
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fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
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impl<O, T: ?Sized> CloneStableDeref for OwningRef<O, T>where O: CloneStableAddress,

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impl<O, T> Eq for OwningRef<O, T>where T: Eq + ?Sized,

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impl<O, T: ?Sized> Send for OwningRef<O, T>where O: Send, for<'a> &'a T: Send,

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impl<O, T: ?Sized> StableDeref for OwningRef<O, T>

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impl<O, T: ?Sized> Sync for OwningRef<O, T>where O: Sync, for<'a> &'a T: Sync,

Auto Trait Implementations§

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impl<O, T: ?Sized> RefUnwindSafe for OwningRef<O, T>where O: RefUnwindSafe, T: RefUnwindSafe,

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impl<O, T: ?Sized> Unpin for OwningRef<O, T>where O: Unpin,

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impl<O, T: ?Sized> UnwindSafe for OwningRef<O, T>where O: UnwindSafe, T: RefUnwindSafe,

Blanket Implementations§

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impl<T> Any for Twhere 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 Twhere T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

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

const: unstable · source§

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

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

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · source§

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> ToOwned for Twhere T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

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 Twhere U: TryFrom<T>,

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

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<'a, T> Captures<'a> for Twhere T: ?Sized,

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impl<T> Erased for T

Layout§

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.