blob: ba8410f041792dd7cb7e45a9ba037207ec9a80cf [file] [log] [blame]
use core::marker::Unpin;
use core::pin::Pin;
use futures_core::future::{FusedFuture, Future};
use futures_core::stream::{FusedStream, Stream};
use futures_core::task::{LocalWaker, Poll};
/// A future of the next element of a stream.
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct Next<'a, St: 'a> {
stream: &'a mut St,
}
impl<St: Stream + Unpin> Unpin for Next<'_, St> {}
impl<'a, St: Stream + Unpin> Next<'a, St> {
pub(super) fn new(stream: &'a mut St) -> Self {
Next { stream }
}
}
impl<St: FusedStream> FusedFuture for Next<'_, St> {
fn is_terminated(&self) -> bool {
self.stream.is_terminated()
}
}
impl<St: Stream + Unpin> Future for Next<'_, St> {
type Output = Option<St::Item>;
fn poll(
mut self: Pin<&mut Self>,
lw: &LocalWaker,
) -> Poll<Self::Output> {
Pin::new(&mut *self.stream).poll_next(lw)
}
}