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// this fails because once there are no more events actively being processed,
// the stream doesn't have anything else to do (so it can't return Ready), but
// also no underlying future or stream has returned NotReady (so it can't
// return NotReady), so it has no valid action to take.
mod run;
#[derive(Debug, PartialEq, Eq)]
struct InputEvent(u32);
#[derive(Debug, PartialEq, Eq)]
struct OutputEvent(u32);
impl InputEvent {
fn into_output_event(
self,
) -> impl futures::future::Future<Item = OutputEvent, Error = String>
{
let InputEvent(i) = self;
futures::future::ok(OutputEvent(i))
}
}
enum State {
Waiting,
Processing(
Box<
dyn futures::future::Future<Item = OutputEvent, Error = String>
+ Send,
>,
),
}
struct IdleStream {
state: State,
}
impl IdleStream {
fn new() -> Self {
Self {
state: State::Waiting,
}
}
fn process(&mut self, event: InputEvent) {
self.state = State::Processing(Box::new(event.into_output_event()));
}
}
impl IdleStream {
#[allow(clippy::type_complexity)]
const POLL_FNS:
&'static [&'static dyn for<'a> Fn(
&'a mut Self,
)
-> component_future::Poll<
Option<OutputEvent>,
String,
>] = &[&Self::poll_state];
fn poll_state(
&mut self,
) -> component_future::Poll<Option<OutputEvent>, String> {
if let State::Processing(fut) = &mut self.state {
let output_event = component_future::try_ready!(fut.poll());
self.state = State::Waiting;
Ok(component_future::Async::Ready(Some(output_event)))
} else {
Ok(component_future::Async::NothingToDo)
}
}
}
impl futures::stream::Stream for IdleStream {
type Item = OutputEvent;
type Error = String;
fn poll(&mut self) -> futures::Poll<Option<Self::Item>, Self::Error> {
component_future::poll_stream(self, Self::POLL_FNS)
}
}
#[test]
#[should_panic]
fn test_panic() {
let mut stream = IdleStream::new();
stream.process(InputEvent(1));
let _ = run::stream(stream);
}
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