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#![allow(warnings)]
use futures::sink::Sink;
use futures::stream::Stream;
use futures::{Async, Poll};
use futures::{AsyncSink, StartSend};
#[derive(Debug)]
#[must_use = "sinks do nothing unless polled"]
pub struct BufferOne<S: Sink> {
sink: S,
buf: Option<Result<S::SinkItem, S::SinkError>>,
}
impl<S: Sink> BufferOne<S> {
pub fn new(sink: S) -> BufferOne<S> {
BufferOne {
sink: sink,
buf: None,
}
}
pub fn get_ref(&self) -> &S {
&self.sink
}
pub fn get_mut(&mut self) -> &mut S {
&mut self.sink
}
pub fn into_inner(self) -> S {
self.sink
}
pub fn poll_ready(&mut self) -> Async<()> {
match self.try_empty_buffer() {
Err(e) => {
self.buf = Some(Err(e));
Async::Ready(())
}
Ok(ready) => ready,
}
}
fn try_empty_buffer(&mut self) -> Poll<(), S::SinkError> {
match self.buf.take() {
Some(Ok(item)) => match try!(self.sink.start_send(item)) {
AsyncSink::Ready => Ok(Async::Ready(())),
AsyncSink::NotReady(item) => {
self.buf = Some(Ok(item));
try!(self.sink.poll_complete());
Ok(Async::NotReady)
}
},
Some(Err(e)) => Err(e),
None => Ok(Async::Ready(())),
}
}
}
impl<S> Stream for BufferOne<S>
where
S: Sink + Stream,
{
type Item = S::Item;
type Error = S::Error;
fn poll(&mut self) -> Poll<Option<S::Item>, S::Error> {
self.sink.poll()
}
}
impl<S: Sink> Sink for BufferOne<S> {
type SinkItem = S::SinkItem;
type SinkError = S::SinkError;
fn start_send(&mut self, item: Self::SinkItem) -> StartSend<Self::SinkItem, Self::SinkError> {
try!(self.try_empty_buffer());
if self.buf.is_some() {
return Ok(AsyncSink::NotReady(item));
}
self.buf = Some(Ok(item));
Ok(AsyncSink::Ready)
}
fn poll_complete(&mut self) -> Poll<(), Self::SinkError> {
try_ready!(self.try_empty_buffer());
debug_assert!(self.buf.is_none());
self.sink.poll_complete()
}
fn close(&mut self) -> Poll<(), Self::SinkError> {
if self.buf.is_some() {
try_ready!(self.try_empty_buffer());
}
assert!(self.buf.is_none());
self.sink.close()
}
}