Enum 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>

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

impl<Fut> Unpin for MaybeDone<Fut>

where Fut: Future + Unpin,

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.