Enum kvarn::prelude::compact_str::core::task::Poll

1.36.0 · source ·
pub enum Poll<T> {
    Ready(T),
    Pending,
}
Available on non-crate feature miri-test-libstd only.
Expand description

Indicates whether a value is available or if the current task has been scheduled to receive a wakeup instead.

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Ready(T)

Represents that a value is immediately ready.

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Pending

Represents that a value is not ready yet.

When a function returns Pending, the function must also ensure that the current task is scheduled to be awoken when progress can be made.

Implementations§

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impl<T> Poll<T>

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pub fn map<U, F>(self, f: F) -> Poll<U>where F: FnOnce(T) -> U,

Maps a Poll<T> to Poll<U> by applying a function to a contained value.

Examples

Converts a Poll<String> into a Poll<usize>, consuming the original:

let poll_some_string = Poll::Ready(String::from("Hello, World!"));
// `Poll::map` takes self *by value*, consuming `poll_some_string`
let poll_some_len = poll_some_string.map(|s| s.len());

assert_eq!(poll_some_len, Poll::Ready(13));
const: 1.49.0 · source

pub const fn is_ready(&self) -> bool

Returns true if the poll is a Poll::Ready value.

Examples
let x: Poll<u32> = Poll::Ready(2);
assert_eq!(x.is_ready(), true);

let x: Poll<u32> = Poll::Pending;
assert_eq!(x.is_ready(), false);
const: 1.49.0 · source

pub const fn is_pending(&self) -> bool

Returns true if the poll is a Pending value.

Examples
let x: Poll<u32> = Poll::Ready(2);
assert_eq!(x.is_pending(), false);

let x: Poll<u32> = Poll::Pending;
assert_eq!(x.is_pending(), true);
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pub fn ready(self) -> Ready<T>

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

Extracts the successful type of a Poll<T>.

When combined with the ? operator, this function will propagate any Poll::Pending values to the caller, and extract the T from Poll::Ready.

Examples
#![feature(poll_ready)]

use std::task::{Context, Poll};
use std::future::{self, Future};
use std::pin::Pin;

pub fn do_poll(cx: &mut Context<'_>) -> Poll<()> {
    let mut fut = future::ready(42);
    let fut = Pin::new(&mut fut);

    let num = fut.poll(cx).ready()?;
    // ... use num

    Poll::Ready(())
}
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impl<T, E> Poll<Result<T, E>>

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pub fn map_ok<U, F>(self, f: F) -> Poll<Result<U, E>>where F: FnOnce(T) -> U,

Maps a Poll<Result<T, E>> to Poll<Result<U, E>> by applying a function to a contained Poll::Ready(Ok) value, leaving all other variants untouched.

This function can be used to compose the results of two functions.

Examples
let res: Poll<Result<u8, _>> = Poll::Ready("12".parse());
let squared = res.map_ok(|n| n * n);
assert_eq!(squared, Poll::Ready(Ok(144)));
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pub fn map_err<U, F>(self, f: F) -> Poll<Result<T, U>>where F: FnOnce(E) -> U,

Maps a Poll::Ready<Result<T, E>> to Poll::Ready<Result<T, F>> by applying a function to a contained Poll::Ready(Err) value, leaving all other variants untouched.

This function can be used to pass through a successful result while handling an error.

Examples
let res: Poll<Result<u8, _>> = Poll::Ready("oops".parse());
let res = res.map_err(|_| 0_u8);
assert_eq!(res, Poll::Ready(Err(0)));
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impl<T, E> Poll<Option<Result<T, E>>>

1.51.0 · source

pub fn map_ok<U, F>(self, f: F) -> Poll<Option<Result<U, E>>>where F: FnOnce(T) -> U,

Maps a Poll<Option<Result<T, E>>> to Poll<Option<Result<U, E>>> by applying a function to a contained Poll::Ready(Some(Ok)) value, leaving all other variants untouched.

This function can be used to compose the results of two functions.

Examples
let res: Poll<Option<Result<u8, _>>> = Poll::Ready(Some("12".parse()));
let squared = res.map_ok(|n| n * n);
assert_eq!(squared, Poll::Ready(Some(Ok(144))));
1.51.0 · source

pub fn map_err<U, F>(self, f: F) -> Poll<Option<Result<T, U>>>where F: FnOnce(E) -> U,

Maps a Poll::Ready<Option<Result<T, E>>> to Poll::Ready<Option<Result<T, F>>> by applying a function to a contained Poll::Ready(Some(Err)) value, leaving all other variants untouched.

This function can be used to pass through a successful result while handling an error.

Examples
let res: Poll<Option<Result<u8, _>>> = Poll::Ready(Some("oops".parse()));
let res = res.map_err(|_| 0_u8);
assert_eq!(res, Poll::Ready(Some(Err(0))));

Trait Implementations§

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impl<T> Clone for Poll<T>where T: Clone,

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fn clone(&self) -> Poll<T>

Returns a copy of the value. Read more
1.0.0 · source§

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

Performs copy-assignment from source. Read more
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impl<T> Debug for Poll<T>where T: Debug,

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

Formats the value using the given formatter. Read more
const: unstable · source§

impl<T> From<T> for Poll<T>

const: unstable · source§

fn from(t: T) -> Poll<T>

Moves the value into a Poll::Ready to make a Poll<T>.

Example
assert_eq!(Poll::from(true), Poll::Ready(true));
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impl<T> FromResidual<Ready<Infallible>> for Poll<T>

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fn from_residual(residual: Ready<Infallible>) -> Poll<T>

🔬This is a nightly-only experimental API. (try_trait_v2)
Constructs the type from a compatible Residual type. Read more
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impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>>where F: From<E>,

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fn from_residual(x: Result<Infallible, E>) -> Poll<Option<Result<T, F>>>

🔬This is a nightly-only experimental API. (try_trait_v2)
Constructs the type from a compatible Residual type. Read more
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impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Result<T, F>>where F: From<E>,

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fn from_residual(x: Result<Infallible, E>) -> Poll<Result<T, F>>

🔬This is a nightly-only experimental API. (try_trait_v2)
Constructs the type from a compatible Residual type. Read more
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impl<T> Hash for Poll<T>where T: Hash,

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

Feeds this value into the given Hasher. Read more
1.3.0 · source§

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<T> Ord for Poll<T>where T: Ord,

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fn cmp(&self, other: &Poll<T>) -> Ordering

This method returns an Ordering between self and other. Read more
1.21.0 · source§

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

Compares and returns the maximum of two values. Read more
1.21.0 · source§

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

Compares and returns the minimum of two values. Read more
1.50.0 · source§

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<T> PartialEq<Poll<T>> for Poll<T>where T: PartialEq<T>,

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fn eq(&self, other: &Poll<T>) -> bool

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

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<T> PartialOrd<Poll<T>> for Poll<T>where T: PartialOrd<T>,

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

This method returns an ordering between self and other values if one exists. Read more
1.0.0 · source§

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator. Read more
1.0.0 · source§

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
1.0.0 · source§

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator. Read more
1.0.0 · source§

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<T, E> Try for Poll<Option<Result<T, E>>>

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type Output = Poll<Option<T>>

🔬This is a nightly-only experimental API. (try_trait_v2)
The type of the value produced by ? when not short-circuiting.
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type Residual = Result<Infallible, E>

🔬This is a nightly-only experimental API. (try_trait_v2)
The type of the value passed to FromResidual::from_residual as part of ? when short-circuiting. Read more
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fn from_output( c: <Poll<Option<Result<T, E>>> as Try>::Output ) -> Poll<Option<Result<T, E>>>

🔬This is a nightly-only experimental API. (try_trait_v2)
Constructs the type from its Output type. Read more
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fn branch( self ) -> ControlFlow<<Poll<Option<Result<T, E>>> as Try>::Residual, <Poll<Option<Result<T, E>>> as Try>::Output>

🔬This is a nightly-only experimental API. (try_trait_v2)
Used in ? to decide whether the operator should produce a value (because this returned ControlFlow::Continue) or propagate a value back to the caller (because this returned ControlFlow::Break). Read more
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impl<T, E> Try for Poll<Result<T, E>>

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type Output = Poll<T>

🔬This is a nightly-only experimental API. (try_trait_v2)
The type of the value produced by ? when not short-circuiting.
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type Residual = Result<Infallible, E>

🔬This is a nightly-only experimental API. (try_trait_v2)
The type of the value passed to FromResidual::from_residual as part of ? when short-circuiting. Read more
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fn from_output(c: <Poll<Result<T, E>> as Try>::Output) -> Poll<Result<T, E>>

🔬This is a nightly-only experimental API. (try_trait_v2)
Constructs the type from its Output type. Read more
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fn branch( self ) -> ControlFlow<<Poll<Result<T, E>> as Try>::Residual, <Poll<Result<T, E>> as Try>::Output>

🔬This is a nightly-only experimental API. (try_trait_v2)
Used in ? to decide whether the operator should produce a value (because this returned ControlFlow::Continue) or propagate a value back to the caller (because this returned ControlFlow::Break). Read more
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impl<T> Copy for Poll<T>where T: Copy,

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impl<T> Eq for Poll<T>where T: Eq,

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impl<T> StructuralEq for Poll<T>

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impl<T> StructuralPartialEq for Poll<T>

Auto Trait Implementations§

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impl<T> RefUnwindSafe for Poll<T>where T: RefUnwindSafe,

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impl<T> Send for Poll<T>where T: Send,

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impl<T> Sync for Poll<T>where T: Sync,

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impl<T> Unpin for Poll<T>where T: Unpin,

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impl<T> UnwindSafe for Poll<T>where T: UnwindSafe,

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<'a, T, E> AsTaggedExplicit<'a, E> for Twhere T: 'a,

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fn explicit(self, class: Class, tag: u32) -> TaggedParser<'a, Explicit, Self, E>

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impl<'a, T, E> AsTaggedImplicit<'a, E> for Twhere T: 'a,

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fn implicit( self, class: Class, constructed: bool, tag: u32 ) -> TaggedParser<'a, Implicit, Self, E>

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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<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<Q, K> Equivalent<K> for Qwhere Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<T> From<!> for T

const: unstable · source§

fn from(t: !) -> T

Converts to this type from the input type.
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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> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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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> Pointable for T

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const ALIGN: usize = mem::align_of::<T>()

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Same<T> for T

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type Output = T

Should always be Self
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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<V, T> VZip<V> for Twhere V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<N> NodeTrait for Nwhere N: Copy + Ord + Hash,