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use futures_core::{Poll, Async, Stream};
use futures_core::task;
use futures_sink::{Sink};
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Flatten<S>
where S: Stream,
{
stream: S,
next: Option<S::Item>,
}
pub fn new<S>(s: S) -> Flatten<S>
where S: Stream,
S::Item: Stream<Error = S::Error>,
{
Flatten {
stream: s,
next: None,
}
}
impl<S: Stream> Flatten<S> {
pub fn get_ref(&self) -> &S {
&self.stream
}
pub fn get_mut(&mut self) -> &mut S {
&mut self.stream
}
pub fn into_inner(self) -> S {
self.stream
}
}
impl<S> Sink for Flatten<S>
where S: Sink + Stream
{
type SinkItem = S::SinkItem;
type SinkError = S::SinkError;
delegate_sink!(stream);
}
impl<S> Stream for Flatten<S>
where S: Stream,
S::Item: Stream,
<S::Item as Stream>::Error: From<S::Error>,
{
type Item = <S::Item as Stream>::Item;
type Error = <S::Item as Stream>::Error;
fn poll_next(&mut self, cx: &mut task::Context) -> Poll<Option<Self::Item>, Self::Error> {
loop {
if self.next.is_none() {
match try_ready!(self.stream.poll_next(cx)) {
Some(e) => self.next = Some(e),
None => return Ok(Async::Ready(None)),
}
}
assert!(self.next.is_some());
match self.next.as_mut().unwrap().poll_next(cx) {
Ok(Async::Ready(None)) => self.next = None,
other => return other,
}
}
}
}