1 files changed, 93 insertions, 0 deletions
diff --git a/vendor/futures-util/src/stream/try_stream/try_fold.rs b/vendor/futures-util/src/stream/try_stream/try_fold.rs
new file mode 100644
index 000000000..d344d96e7
--- /dev/null
+++ b/vendor/futures-util/src/stream/try_stream/try_fold.rs
@@ -0,0 +1,93 @@
+use core::fmt;
+use core::pin::Pin;
+use futures_core::future::{FusedFuture, Future, TryFuture};
+use futures_core::ready;
+use futures_core::stream::TryStream;
+use futures_core::task::{Context, Poll};
+use pin_project_lite::pin_project;
+
+pin_project! {
+    /// Future for the [`try_fold`](super::TryStreamExt::try_fold) method.
+    #[must_use = "futures do nothing unless you `.await` or poll them"]
+    pub struct TryFold<St, Fut, T, F> {
+        #[pin]
+        stream: St,
+        f: F,
+        accum: Option<T>,
+        #[pin]
+        future: Option<Fut>,
+    }
+}
+
+impl<St, Fut, T, F> fmt::Debug for TryFold<St, Fut, T, F>
+where
+    St: fmt::Debug,
+    Fut: fmt::Debug,
+    T: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("TryFold")
+            .field("stream", &self.stream)
+            .field("accum", &self.accum)
+            .field("future", &self.future)
+            .finish()
+    }
+}
+
+impl<St, Fut, T, F> TryFold<St, Fut, T, F>
+where
+    St: TryStream,
+    F: FnMut(T, St::Ok) -> Fut,
+    Fut: TryFuture<Ok = T, Error = St::Error>,
+{
+    pub(super) fn new(stream: St, f: F, t: T) -> Self {
+        Self { stream, f, accum: Some(t), future: None }
+    }
+}
+
+impl<St, Fut, T, F> FusedFuture for TryFold<St, Fut, T, F>
+where
+    St: TryStream,
+    F: FnMut(T, St::Ok) -> Fut,
+    Fut: TryFuture<Ok = T, Error = St::Error>,
+{
+    fn is_terminated(&self) -> bool {
+        self.accum.is_none() && self.future.is_none()
+    }
+}
+
+impl<St, Fut, T, F> Future for TryFold<St, Fut, T, F>
+where
+    St: TryStream,
+    F: FnMut(T, St::Ok) -> Fut,
+    Fut: TryFuture<Ok = T, Error = St::Error>,
+{
+    type Output = Result<T, St::Error>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let mut this = self.project();
+
+        Poll::Ready(loop {
+            if let Some(fut) = this.future.as_mut().as_pin_mut() {
+                // we're currently processing a future to produce a new accum value
+                let res = ready!(fut.try_poll(cx));
+                this.future.set(None);
+                match res {
+                    Ok(a) => *this.accum = Some(a),
+                    Err(e) => break Err(e),
+                }
+            } else if this.accum.is_some() {
+                // we're waiting on a new item from the stream
+                let res = ready!(this.stream.as_mut().try_poll_next(cx));
+                let a = this.accum.take().unwrap();
+                match res {
+                    Some(Ok(item)) => this.future.set(Some((this.f)(a, item))),
+                    Some(Err(e)) => break Err(e),
+                    None => break Ok(a),
+                }
+            } else {
+                panic!("Fold polled after completion")
+            }
+        })
+    }
+}