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use tokio::prelude::*;
#[must_use = "streams do nothing unless polled"]
pub struct SelectAll<S> {
inner: stream::FuturesUnordered<stream::StreamFuture<S>>,
}
impl<S> SelectAll<S> where S: Stream {
pub fn new() -> SelectAll<S> {
SelectAll {
inner: stream::FuturesUnordered::new(),
}
}
pub fn len(&self) -> usize {
self.inner.len()
}
pub fn push(&mut self, stream: S) {
self.inner.push(stream.into_future());
}
}
impl<S> Stream for SelectAll<S> where S: Stream {
type Item = S::Item;
type Error = S::Error;
fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
match self.inner.poll() {
Ok(Async::NotReady) => Ok(Async::NotReady),
Ok(Async::Ready(Some((Some(item), remaining)))) => {
self.push(remaining);
Ok(Async::Ready(Some(item)))
},
Ok(Async::Ready(Some((None, _)))) => {
let _ = self.inner.poll();
Ok(Async::NotReady)
},
Ok(Async::Ready(_)) => Ok(Async::Ready(None)),
Err((e, _)) => Err(e),
}
}
}
pub fn select_all<I, T, E>(streams: I) -> SelectAll<impl Stream<Item=T, Error=E> + Send>
where
I: IntoIterator,
I::Item: Stream<Item=T, Error=E> + Send + 'static,
T: Send + 'static,
E: Send + 'static,
{
let mut select = SelectAll::new();
for stream in streams {
select.push(stream);
}
select
}