| use core::pin::Pin; |
| use futures_core::stream::{FusedStream, Stream}; |
| use futures_core::task::{Context, Poll}; |
| #[cfg(feature = "sink")] |
| use futures_sink::Sink; |
| use pin_project::{pin_project, project}; |
| |
| /// Stream for the [`fuse`](super::StreamExt::fuse) method. |
| #[pin_project] |
| #[derive(Debug)] |
| #[must_use = "streams do nothing unless polled"] |
| pub struct Fuse<St> { |
| #[pin] |
| stream: St, |
| done: bool, |
| } |
| |
| impl<St> Fuse<St> { |
| pub(super) fn new(stream: St) -> Fuse<St> { |
| Fuse { stream, done: false } |
| } |
| |
| /// Returns whether the underlying stream has finished or not. |
| /// |
| /// If this method returns `true`, then all future calls to poll are |
| /// guaranteed to return `None`. If this returns `false`, then the |
| /// underlying stream is still in use. |
| pub fn is_done(&self) -> bool { |
| self.done |
| } |
| |
| delegate_access_inner!(stream, St, ()); |
| } |
| |
| impl<S: Stream> FusedStream for Fuse<S> { |
| fn is_terminated(&self) -> bool { |
| self.done |
| } |
| } |
| |
| impl<S: Stream> Stream for Fuse<S> { |
| type Item = S::Item; |
| |
| #[project] |
| fn poll_next( |
| self: Pin<&mut Self>, |
| cx: &mut Context<'_>, |
| ) -> Poll<Option<S::Item>> { |
| #[project] |
| let Fuse { stream, done } = self.project(); |
| |
| if *done { |
| return Poll::Ready(None); |
| } |
| |
| let item = ready!(stream.poll_next(cx)); |
| if item.is_none() { |
| *done = true; |
| } |
| Poll::Ready(item) |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| if self.done { |
| (0, Some(0)) |
| } else { |
| self.stream.size_hint() |
| } |
| } |
| } |
| |
| // Forwarding impl of Sink from the underlying stream |
| #[cfg(feature = "sink")] |
| impl<S: Stream + Sink<Item>, Item> Sink<Item> for Fuse<S> { |
| type Error = S::Error; |
| |
| delegate_sink!(stream, Item); |
| } |