Fix layer support

src/body.rs

@@ -0,0 +1,71 @@
+use bytes::Buf;
+use http_body::{Body, Empty};
+use std::{
+    fmt,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
+/// A boxed [`Body`] trait object.
+pub struct BoxBody<D, E> {
+    inner: Pin<Box<dyn Body<Data = D, Error = E> + Send + Sync + 'static>>,
+}
+
+impl<D, E> BoxBody<D, E> {
+    /// Create a new `BoxBody`.
+    pub fn new<B>(body: B) -> Self
+    where
+        B: Body<Data = D, Error = E> + Send + Sync + 'static,
+        D: Buf,
+    {
+        Self {
+            inner: Box::pin(body),
+        }
+    }
+}
+
+// TODO(david): upstream this to http-body?
+impl<D, E> Default for BoxBody<D, E>
+where
+    D: bytes::Buf + 'static,
+{
+    fn default() -> Self {
+        BoxBody::new(Empty::<D>::new().map_err(|err| match err {}))
+    }
+}
+
+impl<D, E> fmt::Debug for BoxBody<D, E> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("BoxBody").finish()
+    }
+}
+
+impl<D, E> Body for BoxBody<D, E>
+where
+    D: Buf,
+{
+    type Data = D;
+    type Error = E;
+
+    fn poll_data(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Option<Result<Self::Data, Self::Error>>> {
+        self.inner.as_mut().poll_data(cx)
+    }
+
+    fn poll_trailers(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<Option<http::HeaderMap>, Self::Error>> {
+        self.inner.as_mut().poll_trailers(cx)
+    }
+
+    fn is_end_stream(&self) -> bool {
+        self.inner.is_end_stream()
+    }
+
+    fn size_hint(&self) -> http_body::SizeHint {
+        self.inner.size_hint()
+    }
+}