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use std::fmt;
use futures_core::{Async, IntoFuture, Poll, Stream};
use futures_core::task;
use futures_sink::{Sink};
use stream::{Fuse, FuturesUnordered};
#[must_use = "streams do nothing unless polled"]
pub struct BufferUnordered<S>
where S: Stream,
S::Item: IntoFuture,
{
stream: Fuse<S>,
queue: FuturesUnordered<<S::Item as IntoFuture>::Future>,
max: usize,
}
impl<S> fmt::Debug for BufferUnordered<S>
where S: Stream + fmt::Debug,
S::Item: IntoFuture,
<<S as Stream>::Item as IntoFuture>::Future: fmt::Debug,
{
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("BufferUnordered")
.field("stream", &self.stream)
.field("queue", &self.queue)
.field("max", &self.max)
.finish()
}
}
pub fn new<S>(s: S, amt: usize) -> BufferUnordered<S>
where S: Stream,
S::Item: IntoFuture<Error=<S as Stream>::Error>,
{
BufferUnordered {
stream: super::fuse::new(s),
queue: FuturesUnordered::new(),
max: amt,
}
}
impl<S> BufferUnordered<S>
where S: Stream,
S::Item: IntoFuture<Error=<S as Stream>::Error>,
{
pub fn get_ref(&self) -> &S {
self.stream.get_ref()
}
pub fn get_mut(&mut self) -> &mut S {
self.stream.get_mut()
}
pub fn into_inner(self) -> S {
self.stream.into_inner()
}
}
impl<S> Stream for BufferUnordered<S>
where S: Stream,
S::Item: IntoFuture<Error=<S as Stream>::Error>,
{
type Item = <S::Item as IntoFuture>::Item;
type Error = <S as Stream>::Error;
fn poll_next(&mut self, cx: &mut task::Context) -> Poll<Option<Self::Item>, Self::Error> {
while self.queue.len() < self.max {
let future = match self.stream.poll_next(cx)? {
Async::Ready(Some(s)) => s.into_future(),
Async::Ready(None) |
Async::Pending => break,
};
self.queue.push(future);
}
if let Some(val) = try_ready!(self.queue.poll_next(cx)) {
return Ok(Async::Ready(Some(val)));
}
if self.stream.is_done() {
Ok(Async::Ready(None))
} else {
Ok(Async::Pending)
}
}
}
impl<S> Sink for BufferUnordered<S>
where S: Sink + Stream,
S::Item: IntoFuture,
{
type SinkItem = S::SinkItem;
type SinkError = S::SinkError;
delegate_sink!(stream);
}