feat(http-body): Change return type of Frame::into_* methods from Opt…

…ion<T> to Result<T, Self>

Fixes #77
BREAKING CHANGE: Frame::into_* methods now return Result<T, Self> instead of Option<T>

http-body-util/src/collected.rs

@@ -37,18 +37,21 @@ impl<B: Buf> Collected<B> {
     }
 
     pub(crate) fn push_frame(&mut self, frame: Frame<B>) {
-        if frame.is_data() {
-            let data = frame.into_data().unwrap();
-            self.bufs.push(data);
-        } else if frame.is_trailers() {
-            let trailers = frame.into_trailers().unwrap();
+        let frame = match frame.into_data() {
+            Ok(data) => {
+                self.bufs.push(data);
+                return;
+            }
+            Err(frame) => frame,
+        };
 
+        if let Ok(trailers) = frame.into_trailers() {
             if let Some(current) = &mut self.trailers {
                 current.extend(trailers.into_iter());
             } else {
                 self.trailers = Some(trailers);
             }
-        }
+        };
     }
 }
 

http-body/src/frame.rs

@@ -38,11 +38,12 @@ impl<T> Frame<T> {
 
     /// Consumes self into the buf of the DATA frame.
     ///
-    /// Check `Frame::is_data` before to determine if the frame is DATA.
-    pub fn into_data(self) -> Option<T> {
+    /// Returns an [`Err`] containing the original [`Frame`] when frame is not a DATA frame.
+    /// `Frame::is_data` can also be used to determine if the frame is a DATA frame.
+    pub fn into_data(self) -> Result<T, Self> {
         match self.kind {
-            Kind::Data(data) => Some(data),
-            _ => None,
+            Kind::Data(data) => Ok(data),
+            _ => Err(self),
         }
     }
 
@@ -73,11 +74,12 @@ impl<T> Frame<T> {
 
     /// Consumes self into the buf of the trailers frame.
     ///
-    /// Check `Frame::is_trailers` before to determine if the frame is a trailers frame.
-    pub fn into_trailers(self) -> Option<HeaderMap> {
+    /// Returns an [`Err`] containing the original [`Frame`] when frame is not a trailers frame.
+    /// `Frame::is_trailers` can also be used to determine if the frame is a trailers frame.
+    pub fn into_trailers(self) -> Result<HeaderMap, Self> {
         match self.kind {
-            Kind::Trailers(trailers) => Some(trailers),
-            _ => None,
+            Kind::Trailers(trailers) => Ok(trailers),
+            _ => Err(self),
         }
     }