futures_util::task

Struct FutureObj

pub struct FutureObj<'a, T>(/* private fields */);

Expand description

A custom trait object for polling futures, roughly akin to Box<dyn Future<Output = T> + Send + 'a>.

This custom trait object was introduced as currently it is not possible to take dyn Trait by value and Box<dyn Trait> is not available in no_std contexts.

You should generally not need to use this type outside of no_std or when implementing Spawn, consider using BoxFuture instead.

Implementations§

impl<'a, T> FutureObj<'a, T>

pub fn new<F>(f: F) -> FutureObj<'a, T> ⓘ
where F: UnsafeFutureObj<'a, T> + Send,

Create a FutureObj from a custom trait object representation.

Trait Implementations§

impl<T> Debug for FutureObj<'_, T>

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

Formats the value using the given formatter. Read more

impl<'a, F> From<Box<F>> for FutureObj<'a, ()>
where F: Future<Output = ()> + Send + 'a,

fn from(boxed: Box<F>) -> FutureObj<'a, ()> ⓘ

Converts to this type from the input type.

impl<'a> From<Box<dyn Future<Output = ()> + Send + 'a>> for FutureObj<'a, ()>

fn from(boxed: Box<dyn Future<Output = ()> + Send + 'a>) -> FutureObj<'a, ()> ⓘ

Converts to this type from the input type.

impl<'a, T> From<FutureObj<'a, T>> for LocalFutureObj<'a, T>

fn from(f: FutureObj<'a, T>) -> LocalFutureObj<'a, T> ⓘ

Converts to this type from the input type.

impl<'a, F> From<Pin<Box<F>>> for FutureObj<'a, ()>
where F: Future<Output = ()> + Send + 'a,

fn from(boxed: Pin<Box<F>>) -> FutureObj<'a, ()> ⓘ

Converts to this type from the input type.

impl<'a> From<Pin<Box<dyn Future<Output = ()> + Send + 'a>>> for FutureObj<'a, ()>

fn from( boxed: Pin<Box<dyn Future<Output = ()> + Send + 'a>>, ) -> FutureObj<'a, ()> ⓘ

Converts to this type from the input type.

impl<T> Future for FutureObj<'_, T>

type Output = T

The type of value produced on completion.

fn poll(self: Pin<&mut FutureObj<'_, T>>, cx: &mut Context<'_>) -> Poll<T>

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

impl<T> Send for FutureObj<'_, T>

impl<T> Unpin for FutureObj<'_, T>

Auto Trait Implementations§

impl<'a, T> Freeze for FutureObj<'a, T>

impl<'a, T> !RefUnwindSafe for FutureObj<'a, T>

impl<'a, T> !Sync for FutureObj<'a, T>

impl<'a, T> !UnwindSafe for FutureObj<'a, T>

Blanket Implementations§

impl<T> Any for T
where T: 'static + ?Sized,

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

impl<T> Borrow<T> for T
where T: ?Sized,

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

impl<T> BorrowMut<T> for T
where T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

impl<T> From<T> for T

fn from(t: T) -> T

Returns the argument unchanged.

impl<T> FutureExt for T
where T: Future + ?Sized,

fn map<U, F>(self, f: F) -> Map<Self, F> ⓘ
where F: FnOnce(Self::Output) -> U, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more

fn map_into<U>(self) -> MapInto<Self, U> ⓘ
where Self::Output: Into<U>, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more

fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F> ⓘ
where F: FnOnce(Self::Output) -> Fut, Fut: Future, Self: Sized,

Chain on a computation for when a future finished, passing the result of the future to the provided closure f. Read more

fn left_future<B>(self) -> Either<Self, B> ⓘ
where B: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the left-hand variant of that Either. Read more

fn right_future<A>(self) -> Either<A, Self> ⓘ
where A: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the right-hand variant of that Either. Read more

fn into_stream(self) -> IntoStream<Self>
where Self: Sized,

Convert this future into a single element stream. Read more

fn flatten(self) -> Flatten<Self> ⓘ
where Self::Output: Future, Self: Sized,

Flatten the execution of this future when the output of this future is itself another future. Read more

fn flatten_stream(self) -> FlattenStream<Self>
where Self::Output: Stream, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more

fn fuse(self) -> Fuse<Self> ⓘ
where Self: Sized,

Fuse a future such that poll will never again be called once it has completed. This method can be used to turn any Future into a FusedFuture. Read more

fn inspect<F>(self, f: F) -> Inspect<Self, F> ⓘ
where F: FnOnce(&Self::Output), Self: Sized,

Do something with the output of a future before passing it on. Read more

fn boxed<'a>(self) -> BoxFuture<'a, Self::Output>
where Self: Sized + Send + 'a,

Wrap the future in a Box, pinning it. Read more

fn boxed_local<'a>(self) -> LocalBoxFuture<'a, Self::Output>
where Self: Sized + 'a,

Wrap the future in a Box, pinning it. Read more

fn unit_error(self) -> UnitError<Self> ⓘ
where Self: Sized,

Turns a Future<Output = T> into a TryFuture<Ok = T, Error = ()>.

fn never_error(self) -> NeverError<Self> ⓘ
where Self: Sized,

Turns a Future<Output = T> into a TryFuture<Ok = T, Error = Never>.

fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
where Self: Unpin,

A convenience for calling Future::poll on Unpin future types.

fn now_or_never(self) -> Option<Self::Output>
where Self: Sized,

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to Future::poll. Read more

impl<T, U> Into<U> for T
where U: From<T>,

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

impl<F> IntoFuture for F
where F: Future,

type Output = <F as Future>::Output

The output that the future will produce on completion.

type IntoFuture = F

Which kind of future are we turning this into?

fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more

impl<T, U> TryFrom<U> for T
where U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

impl<F, T, E> TryFuture for F
where F: Future<Output = Result<T, E>> + ?Sized,

type Ok = T

The type of successful values yielded by this future

type Error = E

The type of failures yielded by this future

fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this TryFuture as if it were a Future. Read more

impl<Fut> TryFutureExt for Fut
where Fut: TryFuture + ?Sized,

fn map_ok<T, F>(self, f: F) -> MapOk<Self, F> ⓘ
where F: FnOnce(Self::Ok) -> T, Self: Sized,

Maps this future’s success value to a different value. Read more

fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E> ⓘ
where F: FnOnce(Self::Ok) -> T, E: FnOnce(Self::Error) -> T, Self: Sized,

Maps this future’s success value to a different value, and permits for error handling resulting in the same type. Read more

fn map_err<E, F>(self, f: F) -> MapErr<Self, F> ⓘ
where F: FnOnce(Self::Error) -> E, Self: Sized,

Maps this future’s error value to a different value. Read more

fn err_into<E>(self) -> ErrInto<Self, E> ⓘ
where Self: Sized, Self::Error: Into<E>,

Maps this future’s Error to a new error type using the Into trait. Read more

fn ok_into<U>(self) -> OkInto<Self, U> ⓘ
where Self: Sized, Self::Ok: Into<U>,

Maps this future’s Ok to a new type using the Into trait.

fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F> ⓘ
where F: FnOnce(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more

fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F> ⓘ
where F: FnOnce(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more

fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F> ⓘ
where F: FnOnce(&Self::Ok), Self: Sized,

Do something with the success value of a future before passing it on. Read more

fn inspect_err<F>(self, f: F) -> InspectErr<Self, F> ⓘ
where F: FnOnce(&Self::Error), Self: Sized,

Do something with the error value of a future before passing it on. Read more

fn try_flatten(self) -> TryFlatten<Self, Self::Ok> ⓘ
where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is another future. Read more

fn try_flatten_stream(self) -> TryFlattenStream<Self>
where Self::Ok: TryStream<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more

fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F> ⓘ
where Self: Sized, F: FnOnce(Self::Error) -> Self::Ok,

Unwraps this future’s output, producing a future with this future’s Ok type as its Output type. Read more

fn into_future(self) -> IntoFuture<Self> ⓘ
where Self: Sized,

Wraps a TryFuture into a type that implements Future. Read more

fn try_poll_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<Self::Ok, Self::Error>>
where Self: Unpin,

A convenience method for calling TryFuture::try_poll on Unpin future types.

impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.