feat(body): implement http_body::Body for hyper::Body

This adds a `http_body::Body` impl for hypers `Body`. This should
allow us to start moving to a more generic body trait based on
`BufStream` and `http-body`.

Cargo.toml

@@ -22,6 +22,7 @@ bytes = "0.4.4"
 futures = "0.1.21"
 futures-cpupool = { version = "0.1.6", optional = true }
 http = "0.1.15"
+http-body = "0.1"
 httparse = "1.0"
 h2 = "0.1.10"
 iovec = "0.1"
@@ -30,6 +31,7 @@ log = "0.4"
 net2 = { version = "0.2.32", optional = true }
 time = "0.1"
 tokio = { version = "0.1.14", optional = true, default-features = false, features = ["rt-full"] }
+tokio-buf = "0.1"
 tokio-executor = { version = "0.1.0", optional = true }
 tokio-io = "0.1"
 tokio-reactor = { version = "0.1", optional = true }

src/body/body.rs

@@ -4,6 +4,7 @@ use std::fmt;
 use bytes::Bytes;
 use futures::sync::{mpsc, oneshot};
 use futures::{Async, Future, Poll, Stream, Sink, AsyncSink, StartSend};
+use tokio_buf::SizeHint;
 use h2;
 use http::HeaderMap;
 
@@ -332,6 +333,36 @@ impl Payload for Body {
     }
 }
 
+impl ::http_body::Body for Body {
+    type Data = Chunk;
+    type Error = ::Error;
+
+    fn poll_data(&mut self) -> Poll<Option<Self::Data>, Self::Error> {
+        <Self as Payload>::poll_data(self)
+    }
+
+    fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, Self::Error> {
+        <Self as Payload>::poll_trailers(self)
+    }
+
+    fn is_end_stream(&self) -> bool {
+        <Self as Payload>::is_end_stream(self)
+    }
+
+    fn size_hint(&self) -> SizeHint {
+        let mut hint = SizeHint::default();
+
+        let content_length = <Self as Payload>::content_length(self);
+
+        if let Some(size) = content_length {
+            hint.set_upper(size);
+            hint.set_lower(size)
+        }
+
+        hint
+    }
+}
+
 impl Stream for Body {
     type Item = Chunk;
     type Error = ::Error;

src/lib.rs

@@ -22,6 +22,7 @@ extern crate bytes;
 #[cfg(feature = "runtime")] extern crate futures_cpupool;
 extern crate h2;
 #[doc(hidden)] pub extern crate http;
+extern crate http_body;
 extern crate httparse;
 extern crate iovec;
 extern crate itoa;
@@ -29,6 +30,7 @@ extern crate itoa;
 #[cfg(feature = "runtime")] extern crate net2;
 extern crate time;
 #[cfg(feature = "runtime")] extern crate tokio;
+extern crate tokio_buf;
 #[cfg(feature = "runtime")] extern crate tokio_executor;
 #[macro_use] extern crate tokio_io;
 #[cfg(feature = "runtime")] extern crate tokio_reactor;