Struct std::pin::Pin

#[lang = "pin"]
#[repr(transparent)]
pub struct Pin<P> { /* fields omitted */ }

A pinned pointer.

This is a wrapper around a kind of pointer which makes that pointer "pin" its value in place, preventing the value referenced by that pointer from being moved unless it implements Unpin.

See the pin module documentation for further explanation on pinning.

Methods

impl<P> Pin<P> where
    P: Deref,
    <P as Deref>::Target: Unpin, 

pub fn new(pointer: P) -> Pin<P>

Construct a new Pin around a pointer to some data of a type that implements Unpin.

impl<P> Pin<P> where
    P: Deref, 

pub unsafe fn new_unchecked(pointer: P) -> Pin<P>

Construct a new Pin around a reference to some data of a type that may or may not implement Unpin.

Safety

This constructor is unsafe because we cannot guarantee that the data pointed to by pointer is pinned. If the constructed Pin<P> does not guarantee that the data P points to is pinned, constructing a Pin<P> is undefined behavior.

If pointer dereferences to an Unpin type, Pin::new should be used instead.

pub fn as_ref(&self) -> Pin<&<P as Deref>::Target>

Get a pinned shared reference from this pinned pointer.

impl<P> Pin<P> where
    P: DerefMut, 

pub fn as_mut(&mut self) -> Pin<&mut <P as Deref>::Target>

Get a pinned mutable reference from this pinned pointer.

pub fn set(&mut self, value: <P as Deref>::Target) where
    <P as Deref>::Target: Sized, 

Assign a new value to the memory behind the pinned reference.

impl<'a, T> Pin<&'a T> where
    T: ?Sized, 

pub unsafe fn map_unchecked<U, F>(self, func: F) -> Pin<&'a U> where
    F: FnOnce(&T) -> &U, 

Construct a new pin by mapping the interior value.

For example, if you wanted to get a Pin of a field of something, you could use this to get access to that field in one line of code.

Safety

This function is unsafe. You must guarantee that the data you return will not move so long as the argument value does not move (for example, because it is one of the fields of that value), and also that you do not move out of the argument you receive to the interior function.

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W

pub fn get_ref(self) -> &'a T

Get a shared reference out of a pin.

Note: Pin also implements Deref to the target, which can be used to access the inner value. However, Deref only provides a reference that lives for as long as the borrow of the Pin, not the lifetime of the Pin itself. This method allows turning the Pin into a reference with the same lifetime as the original Pin.

impl<'a, T> Pin<&'a mut T> where
    T: ?Sized, 

pub fn into_ref(self) -> Pin<&'a T>

Convert this Pin<&mut T> into a Pin<&T> with the same lifetime.

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W

pub fn get_mut(self) -> &'a mut T where
    T: Unpin, 

Get a mutable reference to the data inside of this Pin.

This requires that the data inside this Pin is Unpin.

Note: Pin also implements DerefMut to the data, which can be used to access the inner value. However, DerefMut only provides a reference that lives for as long as the borrow of the Pin, not the lifetime of the Pin itself. This method allows turning the Pin into a reference with the same lifetime as the original Pin.

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W

pub unsafe fn get_unchecked_mut(self) -> &'a mut T

Get a mutable reference to the data inside of this Pin.

Safety

This function is unsafe. You must guarantee that you will never move the data out of the mutable reference you receive when you call this function, so that the invariants on the Pin type can be upheld.

If the underlying data is Unpin, Pin::get_mut should be used instead.

pub unsafe fn map_unchecked_mut<U, F>(self, func: F) -> Pin<&'a mut U> where
    F: FnOnce(&mut T) -> &mut U, 

Construct a new pin by mapping the interior value.

For example, if you wanted to get a Pin of a field of something, you could use this to get access to that field in one line of code.

Safety

This function is unsafe. You must guarantee that the data you return will not move so long as the argument value does not move (for example, because it is one of the fields of that value), and also that you do not move out of the argument you receive to the interior function.

Trait Implementations

impl<P, Q> PartialOrd<Pin<Q>> for Pin<P> where
    P: PartialOrd<Q>, 

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

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Pin<Q>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Pin<Q>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Pin<Q>) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Pin<Q>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<P> Ord for Pin<P> where
    P: Ord, 

fn cmp(&self, other: &Pin<P>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl<P> Pointer for Pin<P> where
    P: Pointer, 

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

Formats the value using the given formatter.

impl<'a, P, U> DispatchFromDyn<Pin<U>> for Pin<P> where
    P: DispatchFromDyn<U>, 

impl<P> Eq for Pin<P> where
    P: Eq, 

impl<P, Q> PartialEq<Pin<Q>> for Pin<P> where
    P: PartialEq<Q>, 

fn eq(&self, other: &Pin<Q>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Pin<Q>) -> bool

This method tests for !=.

impl<P> Debug for Pin<P> where
    P: Debug, 

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

Formats the value using the given formatter.

impl<P> Hash for Pin<P> where
    P: Hash, 

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

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl<P> Copy for Pin<P> where
    P: Copy, 

impl<P> Future for Pin<P> where
    P: Unpin + DerefMut,
    <P as Deref>::Target: Future, 

type Output = <<P as Deref>::Target as Future>::Output

🔬 This is a nightly-only experimental API. (futures_api #50547)

futures in libcore are unstable

The result of the Future.

fn poll(
    self: Pin<&mut Pin<P>>,
    lw: &LocalWaker
) -> Poll<<Pin<P> as Future>::Output>

🔬 This is a nightly-only experimental API. (futures_api #50547)

futures in libcore are unstable

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.

impl<P> DerefMut for Pin<P> where
    P: DerefMut,
    <P as Deref>::Target: Unpin, 

fn deref_mut(&mut self) -> &mut <P as Deref>::Target

Mutably dereferences the value.

impl<P> Deref for Pin<P> where
    P: Deref, 

type Target = <P as Deref>::Target

The resulting type after dereferencing.

fn deref(&self) -> &<P as Deref>::Target

Dereferences the value.

impl<'_, G> Generator for Pin<&'_ mut G> where
    G: Generator + ?Sized, 

type Yield = <G as Generator>::Yield

🔬 This is a nightly-only experimental API. (generator_trait #43122)

The type of value this generator yields.

type Return = <G as Generator>::Return

🔬 This is a nightly-only experimental API. (generator_trait #43122)

The type of value this generator returns.

fn resume(
    self: Pin<&mut Pin<&'_ mut G>>
) -> GeneratorState<<Pin<&'_ mut G> as Generator>::Yield, <Pin<&'_ mut G> as Generator>::Return>

🔬 This is a nightly-only experimental API. (generator_trait #43122)

Resumes the execution of this generator.

impl<P> Display for Pin<P> where
    P: Display, 

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

Formats the value using the given formatter.

impl<P, U> CoerceUnsized<Pin<U>> for Pin<P> where
    P: CoerceUnsized<U>, 

impl<P> Clone for Pin<P> where
    P: Clone, 

fn clone(&self) -> Pin<P>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<G> Generator for Pin<Box<G>> where
    G: Generator + ?Sized, 

type Yield = <G as Generator>::Yield

🔬 This is a nightly-only experimental API. (generator_trait #43122)

The type of value this generator yields.

type Return = <G as Generator>::Return

🔬 This is a nightly-only experimental API. (generator_trait #43122)

The type of value this generator returns.

fn resume(
    self: Pin<&mut Pin<Box<G>>>
) -> GeneratorState<<Pin<Box<G>> as Generator>::Yield, <Pin<Box<G>> as Generator>::Return>

🔬 This is a nightly-only experimental API. (generator_trait #43122)

Resumes the execution of this generator.

impl<T> From<Box<T>> for Pin<Box<T>> where
    T: ?Sized, 

fn from(boxed: Box<T>) -> Pin<Box<T>>

Converts a Box<T> into a Pin<Box<T>>

This conversion does not allocate on the heap and happens in place.