1 files changed, 111 insertions, 0 deletions
diff --git a/third_party/rust/hyper/src/server/accept.rs b/third_party/rust/hyper/src/server/accept.rs
new file mode 100644
index 0000000000..4b7a1487dd
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+++ b/third_party/rust/hyper/src/server/accept.rs
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+//! The `Accept` trait and supporting types.
+//!
+//! This module contains:
+//!
+//! - The [`Accept`](Accept) trait used to asynchronously accept incoming
+//!   connections.
+//! - Utilities like `poll_fn` to ease creating a custom `Accept`.
+
+#[cfg(feature = "stream")]
+use futures_core::Stream;
+#[cfg(feature = "stream")]
+use pin_project_lite::pin_project;
+
+use crate::common::{
+    task::{self, Poll},
+    Pin,
+};
+
+/// Asynchronously accept incoming connections.
+pub trait Accept {
+    /// The connection type that can be accepted.
+    type Conn;
+    /// The error type that can occur when accepting a connection.
+    type Error;
+
+    /// Poll to accept the next connection.
+    fn poll_accept(
+        self: Pin<&mut Self>,
+        cx: &mut task::Context<'_>,
+    ) -> Poll<Option<Result<Self::Conn, Self::Error>>>;
+}
+
+/// Create an `Accept` with a polling function.
+///
+/// # Example
+///
+/// ```
+/// use std::task::Poll;
+/// use hyper::server::{accept, Server};
+///
+/// # let mock_conn = ();
+/// // If we created some mocked connection...
+/// let mut conn = Some(mock_conn);
+///
+/// // And accept just the mocked conn once...
+/// let once = accept::poll_fn(move |cx| {
+///     Poll::Ready(conn.take().map(Ok::<_, ()>))
+/// });
+///
+/// let builder = Server::builder(once);
+/// ```
+pub fn poll_fn<F, IO, E>(func: F) -> impl Accept<Conn = IO, Error = E>
+where
+    F: FnMut(&mut task::Context<'_>) -> Poll<Option<Result<IO, E>>>,
+{
+    struct PollFn<F>(F);
+
+    // The closure `F` is never pinned
+    impl<F> Unpin for PollFn<F> {}
+
+    impl<F, IO, E> Accept for PollFn<F>
+    where
+        F: FnMut(&mut task::Context<'_>) -> Poll<Option<Result<IO, E>>>,
+    {
+        type Conn = IO;
+        type Error = E;
+        fn poll_accept(
+            self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+        ) -> Poll<Option<Result<Self::Conn, Self::Error>>> {
+            (self.get_mut().0)(cx)
+        }
+    }
+
+    PollFn(func)
+}
+
+/// Adapt a `Stream` of incoming connections into an `Accept`.
+///
+/// # Optional
+///
+/// This function requires enabling the `stream` feature in your
+/// `Cargo.toml`.
+#[cfg(feature = "stream")]
+pub fn from_stream<S, IO, E>(stream: S) -> impl Accept<Conn = IO, Error = E>
+where
+    S: Stream<Item = Result<IO, E>>,
+{
+    pin_project! {
+        struct FromStream<S> {
+            #[pin]
+            stream: S,
+        }
+    }
+
+    impl<S, IO, E> Accept for FromStream<S>
+    where
+        S: Stream<Item = Result<IO, E>>,
+    {
+        type Conn = IO;
+        type Error = E;
+        fn poll_accept(
+            self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+        ) -> Poll<Option<Result<Self::Conn, Self::Error>>> {
+            self.project().stream.poll_next(cx)
+        }
+    }
+
+    FromStream { stream }
+}