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use BufStream;
use either::Either;
use futures::Poll;
#[derive(Debug)]
pub struct Chain<T, U> {
left: Option<T>,
right: U,
}
impl<T, U> Chain<T, U> {
pub(crate) fn new(left: T, right: U) -> Chain<T, U> {
Chain {
left: Some(left),
right,
}
}
}
impl<T, U> BufStream for Chain<T, U>
where
T: BufStream,
U: BufStream<Error = T::Error>,
{
type Item = Either<T::Item, U::Item>;
type Error = T::Error;
fn poll_buf(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
if let Some(ref mut stream) = self.left {
let res = try_ready!(stream.poll_buf());
if res.is_some() {
return Ok(res.map(Either::Left).into());
}
}
self.left = None;
let res = try_ready!(self.right.poll_buf());
Ok(res.map(Either::Right).into())
}
}