make body return borrowed decoder

src/async_impl/body.rs

@@ -66,6 +66,13 @@ pub struct Chunk {
     inner: ::hyper::Chunk,
 }
 
+impl AsRef<[u8]> for Chunk {
+    #[inline]
+    fn as_ref(&self) -> &[u8] {
+        &*self
+    }
+}
+
 impl ::std::ops::Deref for Chunk {
     type Target = [u8];
     #[inline]

src/async_impl/decoder.rs

@@ -82,6 +82,19 @@ impl fmt::Debug for Decoder {
 }
 
 impl Decoder {
+    /// An empty decoder.
+    /// 
+    /// This decoder will produce a single 0 byte chunk.
+    #[inline]
+    pub fn empty() -> Decoder {
+        Decoder {
+            inner: Inner::PlainText(body::empty())
+        }
+    }
+
+    /// A plain text decoder.
+    /// 
+    /// This decoder will emit the underlying chunks as-is.
     #[inline]
     fn plain_text(body: Body) -> Decoder {
         Decoder {
@@ -89,6 +102,9 @@ impl Decoder {
         }
     }
 
+    /// A gzip decoder.
+    /// 
+    /// This decoder will buffer and decompress chunks that are gzipped.
     #[inline]
     fn gzip(mut body: Body) -> Decoder {
         Decoder {
@@ -385,14 +401,6 @@ impl<S> ReadableChunks<S>
 
 // pub(crate)
 
-#[inline]
-pub fn take(decoder: &mut Decoder) -> Decoder {
-    let inner = mem::replace(&mut decoder.inner, Inner::PlainText(body::empty()));
-    Decoder {
-        inner: inner,
-    }
-}
-
 /// Constructs a Decoder from a hyper request.
 ///
 /// A decoder is just a wrapper around the hyper request that knows

src/async_impl/response.rs

@@ -63,17 +63,17 @@ impl Response {
     /// 
     /// This function will replace the body on the response with an empty one.
     #[inline]
-    pub fn body(&mut self) -> Decoder {
-        decoder::take(&mut self.body)
+    pub fn body(&self) -> &Decoder {
+        &self.body
     }
 
     /// Try to deserialize the response body as JSON using `serde`.
     #[inline]
     pub fn json<T: DeserializeOwned>(&mut self) -> Json<T> {
-        let body = self.body().concat2();
-
+        let body = mem::replace(&mut self.body, Decoder::empty());
+        
         Json {
-            concat: body,
+            concat: body.concat2(),
             _marker: PhantomData,
         }
     }