tokio_stream/stream_ext/
fuse.rs

1use crate::Stream;
2
3use pin_project_lite::pin_project;
4use std::pin::Pin;
5use std::task::{ready, Context, Poll};
6
7pin_project! {
8    /// Stream returned by [`fuse()`][super::StreamExt::fuse].
9    #[derive(Debug)]
10    pub struct Fuse<T> {
11        #[pin]
12        stream: Option<T>,
13    }
14}
15
16impl<T> Fuse<T>
17where
18    T: Stream,
19{
20    pub(crate) fn new(stream: T) -> Fuse<T> {
21        Fuse {
22            stream: Some(stream),
23        }
24    }
25}
26
27impl<T> Stream for Fuse<T>
28where
29    T: Stream,
30{
31    type Item = T::Item;
32
33    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T::Item>> {
34        let res = match Option::as_pin_mut(self.as_mut().project().stream) {
35            Some(stream) => ready!(stream.poll_next(cx)),
36            None => return Poll::Ready(None),
37        };
38
39        if res.is_none() {
40            // Do not poll the stream anymore
41            self.as_mut().project().stream.set(None);
42        }
43
44        Poll::Ready(res)
45    }
46
47    fn size_hint(&self) -> (usize, Option<usize>) {
48        match self.stream {
49            Some(ref stream) => stream.size_hint(),
50            None => (0, Some(0)),
51        }
52    }
53}
tokio_stream/stream_ext/fuse.rs

tokio_stream/stream_ext/
fuse.rs
