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author | Ivan Lozano <ivanlozano@google.com> | 2021-01-25 21:39:17 -0500 |
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committer | Ivan Lozano <ivanlozano@google.com> | 2021-01-25 22:05:46 -0500 |
commit | c0f49ebcec57f841f20a5a984b0fe3c94c7dd531 (patch) | |
tree | 08efa1ccbef1a7ef36c8b30afc594f438eecffd9 /src/stream_ext/try_next.rs | |
parent | a285a7c3d95f91b86b3cb1fbe87e1010156570a6 (diff) | |
download | tokio-stream-c0f49ebcec57f841f20a5a984b0fe3c94c7dd531.tar.gz |
Initial import of tokio_stream
Test: N/A
Bug: 177808007
Change-Id: Icff6d8835b59a9b6b286de1ffe8b2f167928473c
Diffstat (limited to 'src/stream_ext/try_next.rs')
-rw-r--r-- | src/stream_ext/try_next.rs | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/src/stream_ext/try_next.rs b/src/stream_ext/try_next.rs new file mode 100644 index 0000000..af27d87 --- /dev/null +++ b/src/stream_ext/try_next.rs @@ -0,0 +1,39 @@ +use crate::stream_ext::Next; +use crate::Stream; + +use core::future::Future; +use core::marker::PhantomPinned; +use core::pin::Pin; +use core::task::{Context, Poll}; +use pin_project_lite::pin_project; + +pin_project! { + /// Future for the [`try_next`](super::StreamExt::try_next) method. + #[derive(Debug)] + #[must_use = "futures do nothing unless you `.await` or poll them"] + pub struct TryNext<'a, St: ?Sized> { + #[pin] + inner: Next<'a, St>, + // Make this future `!Unpin` for compatibility with async trait methods. + #[pin] + _pin: PhantomPinned, + } +} + +impl<'a, St: ?Sized> TryNext<'a, St> { + pub(super) fn new(stream: &'a mut St) -> Self { + Self { + inner: Next::new(stream), + _pin: PhantomPinned, + } + } +} + +impl<T, E, St: ?Sized + Stream<Item = Result<T, E>> + Unpin> Future for TryNext<'_, St> { + type Output = Result<Option<T>, E>; + + fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { + let me = self.project(); + me.inner.poll(cx).map(Option::transpose) + } +} |