Enum futures::task::Poll

#[must_use = "this `Poll` may be a `Pending` variant, which should be handled"]
pub enum Poll<T> {
    Ready(T),
    Pending,
}

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

Variants

Ready(T)

Represents that a value is immediately ready.

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

impl<T> Poll<T>

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

Changes the ready value of this Poll with the closure provided.

pub const fn is_ready(&self) -> bool

Returns true if this is Poll::Ready

pub const fn is_pending(&self) -> bool

Returns true if this is Poll::Pending

impl<T, E> Poll<Result<T, E>>

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

Changes the success value of this Poll with the closure provided.

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

Changes the error value of this Poll with the closure provided.

impl<T, E> Poll<Option<Result<T, E>>>

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

Changes the success value of this Poll with the closure provided.

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

Changes the error value of this Poll with the closure provided.

Trait Implementations

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

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

Returns a copy of the value.

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

Performs copy-assignment from source.

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

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

Formats the value using the given formatter.

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

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

Convert to a Ready variant.

Example

assert_eq!(Poll::from(true), Poll::Ready(true));

impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>> where
    F: From<E>, 

pub 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.

impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Result<T, F>> where
    F: From<E>, 

pub 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.

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

pub fn hash<__H>(&self, state: &mut __H) where
    __H: 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<T> Ord for Poll<T> where
    T: Ord, 

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

This method returns an Ordering between self and other.

#[must_use]

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

Compares and returns the maximum of two values.

#[must_use]

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

Compares and returns the minimum of two values.

#[must_use]

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

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

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

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

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

This method tests for !=.

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

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

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

#[must_use]

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

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

#[must_use]

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

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

#[must_use]

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

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

#[must_use]

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

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

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

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.

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.

pub 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.

pub 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).

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

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.

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.

pub 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.

pub 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).

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

type Ok = Poll<Option<T>>

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

The type of this value when viewed as successful.

type Error = E

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

The type of this value when viewed as failed.

pub fn into_result(
    self
) -> Result<<Poll<Option<Result<T, E>>> as Try>::Ok, <Poll<Option<Result<T, E>>> as Try>::Error>

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

Applies the “?” operator. A return of Ok(t) means that the execution should continue normally, and the result of ? is the value t. A return of Err(e) means that execution should branch to the innermost enclosing catch, or return from the function.

pub fn from_error(
    e: <Poll<Option<Result<T, E>>> as Try>::Error
) -> Poll<Option<Result<T, E>>>

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

Wrap an error value to construct the composite result. For example, Result::Err(x) and Result::from_error(x) are equivalent.

pub fn from_ok(
    x: <Poll<Option<Result<T, E>>> as Try>::Ok
) -> Poll<Option<Result<T, E>>>

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

Wrap an OK value to construct the composite result. For example, Result::Ok(x) and Result::from_ok(x) are equivalent.

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

type Ok = Poll<T>

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

The type of this value when viewed as successful.

type Error = E

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

The type of this value when viewed as failed.

pub fn into_result(
    self
) -> Result<<Poll<Result<T, E>> as Try>::Ok, <Poll<Result<T, E>> as Try>::Error>

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

Applies the “?” operator. A return of Ok(t) means that the execution should continue normally, and the result of ? is the value t. A return of Err(e) means that execution should branch to the innermost enclosing catch, or return from the function.

pub fn from_error(e: <Poll<Result<T, E>> as Try>::Error) -> Poll<Result<T, E>>

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

Wrap an error value to construct the composite result. For example, Result::Err(x) and Result::from_error(x) are equivalent.

pub fn from_ok(x: <Poll<Result<T, E>> as Try>::Ok) -> Poll<Result<T, E>>

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

Wrap an OK value to construct the composite result. For example, Result::Ok(x) and Result::from_ok(x) are equivalent.

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

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

impl<T> StructuralEq for Poll<T>

impl<T> StructuralPartialEq for Poll<T>