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use core::pin::Pin;
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{Context, Poll};
use futures_sink::Sink;
use pin_utils::{unsafe_pinned, unsafe_unpinned};
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct Fuse<St> {
stream: St,
done: bool,
}
impl<St: Unpin> Unpin for Fuse<St> {}
impl<St: Stream> Fuse<St> {
unsafe_pinned!(stream: St);
unsafe_unpinned!(done: bool);
pub(super) fn new(stream: St) -> Fuse<St> {
Fuse { stream, done: false }
}
pub fn is_done(&self) -> bool {
self.done
}
pub fn get_ref(&self) -> &St {
&self.stream
}
pub fn get_mut(&mut self) -> &mut St {
&mut self.stream
}
#[allow(clippy::needless_lifetimes)]
pub fn get_pin_mut<'a>(self: Pin<&'a mut Self>) -> Pin<&'a mut St> {
unsafe { Pin::map_unchecked_mut(self, |x| x.get_mut()) }
}
pub fn into_inner(self) -> St {
self.stream
}
}
impl<S> FusedStream for Fuse<S> {
fn is_terminated(&self) -> bool {
self.done
}
}
impl<S: Stream> Stream for Fuse<S> {
type Item = S::Item;
fn poll_next(
mut self: Pin<&mut Self>,
cx: &mut Context<'_>,
) -> Poll<Option<S::Item>> {
if *self.as_mut().done() {
return Poll::Ready(None);
}
let item = ready!(self.as_mut().stream().poll_next(cx));
if item.is_none() {
*self.as_mut().done() = true;
}
Poll::Ready(item)
}
}
impl<S: Stream + Sink<Item>, Item> Sink<Item> for Fuse<S> {
type SinkError = S::SinkError;
delegate_sink!(stream, Item);
}