Struct core::ptr::Unique [] [src]

pub struct Unique<T: ?Sized> { /* fields omitted */ }
🔬 This is a nightly-only experimental API. (unique #27730)

needs an RFC to flesh out design

A wrapper around a raw non-null *mut T that indicates that the possessor of this wrapper owns the referent. Useful for building abstractions like Box<T>, Vec<T>, String, and HashMap<K, V>.

Unlike *mut T, Unique<T> behaves "as if" it were an instance of T. It implements Send/Sync if T is Send/Sync. It also implies the kind of strong aliasing guarantees an instance of T can expect: the referent of the pointer should not be modified without a unique path to its owning Unique.

If you're uncertain of whether it's correct to use Unique for your purposes, consider using Shared, which has weaker semantics.

Unlike *mut T, the pointer must always be non-null, even if the pointer is never dereferenced. This is so that enums may use this forbidden value as a discriminant -- Option<Unique<T>> has the same size as Unique<T>. However the pointer may still dangle if it isn't dereferenced.

Unlike *mut T, Unique<T> is covariant over T. This should always be correct for any type which upholds Unique's aliasing requirements.

Methods

impl<T: Sized> Unique<T>
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🔬 This is a nightly-only experimental API. (unique #27730)

Creates a new Unique that is dangling, but well-aligned.

This is useful for initializing types which lazily allocate, like Vec::new does.

impl<T: ?Sized> Unique<T>
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🔬 This is a nightly-only experimental API. (unique #27730)

Creates a new Unique.

Safety

ptr must be non-null.

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🔬 This is a nightly-only experimental API. (unique #27730)

Creates a new Unique if ptr is non-null.

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🔬 This is a nightly-only experimental API. (unique #27730)

Acquires the underlying *mut pointer.

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🔬 This is a nightly-only experimental API. (unique #27730)

Dereferences the content.

The resulting lifetime is bound to self so this behaves "as if" it were actually an instance of T that is getting borrowed. If a longer (unbound) lifetime is needed, use &*my_ptr.ptr().

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🔬 This is a nightly-only experimental API. (unique #27730)

Mutably dereferences the content.

The resulting lifetime is bound to self so this behaves "as if" it were actually an instance of T that is getting borrowed. If a longer (unbound) lifetime is needed, use &mut *my_ptr.ptr().

Trait Implementations

impl<T: Send + ?Sized> Send for Unique<T>
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Unique pointers are Send if T is Send because the data they reference is unaliased. Note that this aliasing invariant is unenforced by the type system; the abstraction using the Unique must enforce it.

impl<T: Sync + ?Sized> Sync for Unique<T>
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Unique pointers are Sync if T is Sync because the data they reference is unaliased. Note that this aliasing invariant is unenforced by the type system; the abstraction using the Unique must enforce it.

impl<T: ?Sized> Clone for Unique<T>
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Returns a copy of the value. Read more

1.0.0
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Performs copy-assignment from source. Read more

impl<T: ?Sized> Copy for Unique<T>
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impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where
    T: Unsize<U>, 
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impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where
    T: Unsize<U>, 
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impl<T: ?Sized> Pointer for Unique<T>
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Formats the value using the given formatter.

impl<'a, T: ?Sized> From<&'a mut T> for Unique<T>
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Performs the conversion.

impl<'a, T: ?Sized> From<&'a T> for Unique<T>
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Performs the conversion.

impl<T: ?Sized> From<Unique<T>> for Shared<T>
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Performs the conversion.