1 files changed, 127 insertions, 0 deletions
diff --git a/vendor/futures-util/src/sink/with_flat_map.rs b/vendor/futures-util/src/sink/with_flat_map.rs
new file mode 100644
index 000000000..2ae877a24
--- /dev/null
+++ b/vendor/futures-util/src/sink/with_flat_map.rs
@@ -0,0 +1,127 @@
+use core::fmt;
+use core::marker::PhantomData;
+use core::pin::Pin;
+use futures_core::ready;
+use futures_core::stream::{FusedStream, Stream};
+use futures_core::task::{Context, Poll};
+use futures_sink::Sink;
+use pin_project_lite::pin_project;
+
+pin_project! {
+    /// Sink for the [`with_flat_map`](super::SinkExt::with_flat_map) method.
+    #[must_use = "sinks do nothing unless polled"]
+    pub struct WithFlatMap<Si, Item, U, St, F> {
+        #[pin]
+        sink: Si,
+        f: F,
+        #[pin]
+        stream: Option<St>,
+        buffer: Option<Item>,
+        _marker: PhantomData<fn(U)>,
+    }
+}
+
+impl<Si, Item, U, St, F> fmt::Debug for WithFlatMap<Si, Item, U, St, F>
+where
+    Si: fmt::Debug,
+    St: fmt::Debug,
+    Item: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("WithFlatMap")
+            .field("sink", &self.sink)
+            .field("stream", &self.stream)
+            .field("buffer", &self.buffer)
+            .finish()
+    }
+}
+
+impl<Si, Item, U, St, F> WithFlatMap<Si, Item, U, St, F>
+where
+    Si: Sink<Item>,
+    F: FnMut(U) -> St,
+    St: Stream<Item = Result<Item, Si::Error>>,
+{
+    pub(super) fn new(sink: Si, f: F) -> Self {
+        Self { sink, f, stream: None, buffer: None, _marker: PhantomData }
+    }
+
+    delegate_access_inner!(sink, Si, ());
+
+    fn try_empty_stream(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Si::Error>> {
+        let mut this = self.project();
+
+        if this.buffer.is_some() {
+            ready!(this.sink.as_mut().poll_ready(cx))?;
+            let item = this.buffer.take().unwrap();
+            this.sink.as_mut().start_send(item)?;
+        }
+        if let Some(mut some_stream) = this.stream.as_mut().as_pin_mut() {
+            while let Some(item) = ready!(some_stream.as_mut().poll_next(cx)?) {
+                match this.sink.as_mut().poll_ready(cx)? {
+                    Poll::Ready(()) => this.sink.as_mut().start_send(item)?,
+                    Poll::Pending => {
+                        *this.buffer = Some(item);
+                        return Poll::Pending;
+                    }
+                };
+            }
+        }
+        this.stream.set(None);
+        Poll::Ready(Ok(()))
+    }
+}
+
+// Forwarding impl of Stream from the underlying sink
+impl<S, Item, U, St, F> Stream for WithFlatMap<S, Item, U, St, F>
+where
+    S: Stream + Sink<Item>,
+    F: FnMut(U) -> St,
+    St: Stream<Item = Result<Item, S::Error>>,
+{
+    type Item = S::Item;
+
+    delegate_stream!(sink);
+}
+
+impl<S, Item, U, St, F> FusedStream for WithFlatMap<S, Item, U, St, F>
+where
+    S: FusedStream + Sink<Item>,
+    F: FnMut(U) -> St,
+    St: Stream<Item = Result<Item, S::Error>>,
+{
+    fn is_terminated(&self) -> bool {
+        self.sink.is_terminated()
+    }
+}
+
+impl<Si, Item, U, St, F> Sink<U> for WithFlatMap<Si, Item, U, St, F>
+where
+    Si: Sink<Item>,
+    F: FnMut(U) -> St,
+    St: Stream<Item = Result<Item, Si::Error>>,
+{
+    type Error = Si::Error;
+
+    fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        self.try_empty_stream(cx)
+    }
+
+    fn start_send(self: Pin<&mut Self>, item: U) -> Result<(), Self::Error> {
+        let mut this = self.project();
+
+        assert!(this.stream.is_none());
+        this.stream.set(Some((this.f)(item)));
+        Ok(())
+    }
+
+    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        ready!(self.as_mut().try_empty_stream(cx)?);
+        self.project().sink.poll_flush(cx)
+    }
+
+    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+        ready!(self.as_mut().try_empty_stream(cx)?);
+        self.project().sink.poll_close(cx)
+    }
+}