Struct std::ptr::Unique
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[src]
pub struct Unique<T> where
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> Unique<T>[src]
fn empty() -> Unique<T>[src]
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> Unique<T> where
T: ?Sized, [src]
T: ?Sized,
const unsafe fn new_unchecked(ptr: *mut T) -> Unique<T>[src]
fn new(ptr: *mut T) -> Option<Unique<T>>[src]
Creates a new Unique if ptr is non-null.
fn as_ptr(self) -> *mut T[src]
Acquires the underlying *mut pointer.
unsafe fn as_ref(&self) -> &T[src]
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().
unsafe fn as_mut(&mut self) -> &mut T[src]
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, U> CoerceUnsized<Unique<U>> for Unique<T> where
T: Unsize<U> + ?Sized,
U: ?Sized, [src]
T: Unsize<U> + ?Sized,
U: ?Sized,
impl<T> Clone for Unique<T> where
T: ?Sized, [src]
T: ?Sized,
fn clone(&self) -> Unique<T>[src]
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)1.0.0[src]
Performs copy-assignment from source. Read more
impl<T> Copy for Unique<T> where
T: ?Sized, [src]
T: ?Sized,
impl<'a, T> From<&'a mut T> for Unique<T> where
T: ?Sized, [src]
T: ?Sized,
impl<T> From<Unique<T>> for Shared<T> where
T: ?Sized, [src]
T: ?Sized,
impl<'a, T> From<&'a T> for Unique<T> where
T: ?Sized, [src]
T: ?Sized,
impl<T> Send for Unique<T> where
T: Send + ?Sized, [src]
T: Send + ?Sized,
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 for Unique<T> where
T: Sync + ?Sized, [src]
T: Sync + ?Sized,
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> Pointer for Unique<T> where
T: ?Sized, [src]
T: ?Sized,
fn fmt(&self, f: &mut Formatter) -> Result<(), Error>[src]
Formats the value using the given formatter.