feat(lambda-http): implement http-body::Body for lambda_http::body (#406)

Author: nmoutschen

Diff for: lambda-http/Cargo.toml

@@ -18,7 +18,9 @@ maintenance = { status = "actively-developed" }
 
 [dependencies]
 base64 = "0.13.0"
+bytes = "1"
 http = "0.2"
+http-body = "0.4"
 lambda_runtime = { path = "../lambda-runtime", version = "0.4.1" }
 serde = { version = "^1", features = ["derive"] }
 serde_json = "^1"

Diff for: lambda-http/src/body.rs

@@ -1,9 +1,11 @@
 //! Provides an ALB / API Gateway oriented request and response body entity interface
 
-use std::{borrow::Cow, ops::Deref};
-
+use crate::Error;
 use base64::display::Base64Display;
+use bytes::Bytes;
+use http_body::{Body as HttpBody, SizeHint};
 use serde::ser::{Error as SerError, Serialize, Serializer};
+use std::{borrow::Cow, mem::take, ops::Deref, pin::Pin, task::Poll};
 
 /// Representation of http request and response bodies as supported
 /// by API Gateway and ALBs.
@@ -175,6 +177,45 @@ impl<'a> Serialize for Body {
     }
 }
 
+impl HttpBody for Body {
+    type Data = Bytes;
+    type Error = Error;
+
+    fn poll_data(
+        self: Pin<&mut Self>,
+        _cx: &mut std::task::Context<'_>,
+    ) -> Poll<Option<Result<Self::Data, Self::Error>>> {
+        let body = take(self.get_mut());
+        Poll::Ready(match body {
+            Body::Empty => None,
+            Body::Text(s) => Some(Ok(s.into())),
+            Body::Binary(b) => Some(Ok(b.into())),
+        })
+    }
+
+    fn poll_trailers(
+        self: Pin<&mut Self>,
+        _cx: &mut std::task::Context<'_>,
+    ) -> Poll<Result<Option<http::HeaderMap>, Self::Error>> {
+        Poll::Ready(Ok(None))
+    }
+
+    fn is_end_stream(&self) -> bool {
+        match self {
+            Body::Empty => true,
+            _ => false,
+        }
+    }
+
+    fn size_hint(&self) -> SizeHint {
+        match self {
+            Body::Empty => SizeHint::default(),
+            Body::Text(ref s) => SizeHint::with_exact(s.len() as u64),
+            Body::Binary(ref b) => SizeHint::with_exact(b.len() as u64),
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;