blob: 837c55cfa0a4846c2aaa2dbe473047721df5f68a [file] [log] [blame]
use futures_core::stream::Stream;
use futures_core::task::{LocalWaker, Poll};
use pin_utils::{unsafe_pinned, unsafe_unpinned};
use std::any::Any;
use std::pin::Pin;
use std::panic::{catch_unwind, UnwindSafe, AssertUnwindSafe};
use std::prelude::v1::*;
/// Stream for the `catch_unwind` combinator.
///
/// This is created by the `Stream::catch_unwind` method.
#[derive(Debug)]
#[must_use = "streams do nothing unless polled"]
pub struct CatchUnwind<St: Stream> {
stream: St,
caught_unwind: bool,
}
impl<St: Stream + UnwindSafe> CatchUnwind<St> {
unsafe_pinned!(stream: St);
unsafe_unpinned!(caught_unwind: bool);
pub(super) fn new(stream: St) -> CatchUnwind<St> {
CatchUnwind { stream, caught_unwind: false }
}
}
impl<St: Stream + UnwindSafe> Stream for CatchUnwind<St>
{
type Item = Result<St::Item, Box<dyn Any + Send>>;
fn poll_next(
mut self: Pin<&mut Self>,
lw: &LocalWaker,
) -> Poll<Option<Self::Item>> {
if *self.caught_unwind() {
Poll::Ready(None)
} else {
let res = catch_unwind(AssertUnwindSafe(|| {
self.stream().poll_next(lw)
}));
match res {
Ok(poll) => poll.map(|opt| opt.map(Ok)),
Err(e) => {
*self.caught_unwind() = true;
Poll::Ready(Some(Err(e)))
},
}
}
}
}