Enum futures::future::MaybeDone

pub enum MaybeDone<Fut> where
    Fut: Future,  {
    Future(Fut),
    Done(<Fut as Future>::Output),
    Gone,
}

A future that may have completed.

This is created by the [maybe_done()] function.

Variants

Future(Fut)

A not-yet-completed future

Done(<Fut as Future>::Output)

The output of the completed future

Gone

The empty variant after the result of a [MaybeDone] has been taken using the take_output method.

Implementations

impl<Fut> MaybeDone<Fut> where
    Fut: Future, 

pub fn output_mut(
    self: Pin<&mut MaybeDone<Fut>>
) -> Option<&mut <Fut as Future>::Output>

Returns an [Option] containing a mutable reference to the output of the future. The output of this method will be [Some] if and only if the inner future has been completed and take_output has not yet been called.

pub fn take_output(
    self: Pin<&mut MaybeDone<Fut>>
) -> Option<<Fut as Future>::Output>

Attempt to take the output of a MaybeDone without driving it towards completion.

Trait Implementations

impl<Fut> Debug for MaybeDone<Fut> where
    Fut: Debug + Future,
    <Fut as Future>::Output: Debug, 

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

Formats the value using the given formatter.

impl<Fut> FusedFuture for MaybeDone<Fut> where
    Fut: Future, 

fn is_terminated(&self) -> bool

Returns true if the underlying future should no longer be polled.

impl<Fut> Future for MaybeDone<Fut> where
    Fut: Future, 

type Output = ()

The type of value produced on completion.

fn poll(
    self: Pin<&mut MaybeDone<Fut>>,
    cx: &mut Context
) -> Poll<<MaybeDone<Fut> as Future>::Output>

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

impl<'pin, Fut> Unpin for MaybeDone<Fut> where
    Fut: Future,
    __MaybeDone<'pin, Fut>: Unpin,