1use futures_core::stream::{FusedStream, Stream};
2use futures_core::task::{Context, Poll};
3use pin_project_lite::pin_project;
4use std::any::Any;
5use std::panic::{catch_unwind, AssertUnwindSafe, UnwindSafe};
6use std::pin::Pin;
7
8pin_project! {
9 /// Stream for the [`catch_unwind`](super::StreamExt::catch_unwind) method.
10 #[derive(Debug)]
11 #[must_use = "streams do nothing unless polled"]
12 pub struct CatchUnwind<St> {
13 #[pin]
14 stream: St,
15 caught_unwind: bool,
16 }
17}
18
19impl<St: Stream + UnwindSafe> CatchUnwind<St> {
20 pub(super) fn new(stream: St) -> Self {
21 Self { stream, caught_unwind: false }
22 }
23
24 delegate_access_inner!(stream, St, ());
25}
26
27impl<St: Stream + UnwindSafe> Stream for CatchUnwind<St> {
28 type Item = Result<St::Item, Box<dyn Any + Send>>;
29
30 fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
31 let mut this = self.project();
32
33 if *this.caught_unwind {
34 Poll::Ready(None)
35 } else {
36 let res = catch_unwind(AssertUnwindSafe(|| this.stream.as_mut().poll_next(cx)));
37
38 match res {
39 Ok(poll) => poll.map(|opt| opt.map(Ok)),
40 Err(e) => {
41 *this.caught_unwind = true;
42 Poll::Ready(Some(Err(e)))
43 }
44 }
45 }
46 }
47
48 fn size_hint(&self) -> (usize, Option<usize>) {
49 if self.caught_unwind {
50 (0, Some(0))
51 } else {
52 self.stream.size_hint()
53 }
54 }
55}
56
57impl<St: FusedStream + UnwindSafe> FusedStream for CatchUnwind<St> {
58 fn is_terminated(&self) -> bool {
59 self.caught_unwind || self.stream.is_terminated()
60 }
61}
62