Initial public release of Warp.

Repo-Sync-Origin: warpdotdev/warp-internal@12af1d983b

crates/websocket/src/sink_map_err.rs

@@ -0,0 +1,87 @@
+use core::pin::Pin;
+use futures::{Sink, Stream};
+use futures_util::stream::FusedStream;
+use pin_project::pin_project;
+use std::task::{Context, Poll};
+
+/// Maps the error returned by the [`Sink`] using the provided `err` function.
+pub fn map_err<S, I, E>(sink: S, err: impl FnMut(S::Error) -> E) -> impl Sink<I, Error = E>
+where
+    S: Sink<I>,
+{
+    SinkMapErr::new(sink, err)
+}
+
+/// Helper struct to map the [`Err`] of an underlying [`Sink`].
+/// This is a fork of the the `SinkMapErr` defined within `futures-util`
+/// (https://docs.rs/futures/latest/futures/sink/struct.SinkMapErr.html) except that it does _not_
+/// panic if the caller tries to write to the sink after a previous attempt to write returned an
+/// error. See <https://github.com/rust-lang/futures-rs/issues/2108> for more details about the
+/// issue with the original `SinkMapErr` struct.
+#[pin_project]
+struct SinkMapErr<Si, F> {
+    #[pin]
+    sink: Si,
+    err_function: F,
+}
+
+impl<Si, F> SinkMapErr<Si, F> {
+    fn new(sink: Si, err_function: F) -> Self {
+        Self { sink, err_function }
+    }
+}
+
+impl<Si, F, E, Item> Sink<Item> for SinkMapErr<Si, F>
+where
+    Si: Sink<Item>,
+    F: FnMut(Si::Error) -> E,
+{
+    type Error = E;
+
+    fn poll_ready(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        let project = self.as_mut().project();
+        let err_function = project.err_function;
+        project.sink.poll_ready(cx).map_err(err_function)
+    }
+
+    fn start_send(mut self: Pin<&mut Self>, item: Item) -> Result<(), Self::Error> {
+        let project = self.as_mut().project();
+        let err_function = project.err_function;
+        project.sink.start_send(item).map_err(err_function)
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        let project = self.as_mut().project();
+        let err_function = project.err_function;
+        project.sink.poll_flush(cx).map_err(err_function)
+    }
+
+    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        let project = self.as_mut().project();
+        let err_function = project.err_function;
+        project.sink.poll_close(cx).map_err(err_function)
+    }
+}
+
+/// Implement [`Stream`] by forwarding calls to the underlying [`Sink`].
+impl<S: Stream, F> Stream for SinkMapErr<S, F> {
+    type Item = S::Item;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        self.project().sink.poll_next(cx)
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.sink.size_hint()
+    }
+}
+
+impl<S: FusedStream, F> FusedStream for SinkMapErr<S, F> {
+    fn is_terminated(&self) -> bool {
+        self.sink.is_terminated()
+    }
+}
+
+#[cfg(test)]
+#[path = "sink_map_err_tests.rs"]
+mod tests;