Add UnsyncBoxBody combinator (#50)

Author: LucioFranco

src/combinators/box_body.rs

@@ -11,6 +11,11 @@ pub struct BoxBody<D, E> {
     inner: Pin<Box<dyn Body<Data = D, Error = E> + Send + Sync + 'static>>,
 }
 
+/// A boxed [`Body`] trait object that is !Sync.
+pub struct UnsyncBoxBody<D, E> {
+    inner: Pin<Box<dyn Body<Data = D, Error = E> + Send + 'static>>,
+}
+
 impl<D, E> BoxBody<D, E> {
     /// Create a new `BoxBody`.
     pub fn new<B>(body: B) -> Self
@@ -68,3 +73,62 @@ where
         BoxBody::new(crate::Empty::new().map_err(|err| match err {}))
     }
 }
+
+// === UnsyncBoxBody ===
+impl<D, E> UnsyncBoxBody<D, E> {
+    /// Create a new `BoxBody`.
+    pub fn new<B>(body: B) -> Self
+    where
+        B: Body<Data = D, Error = E> + Send + 'static,
+        D: Buf,
+    {
+        Self {
+            inner: Box::pin(body),
+        }
+    }
+}
+
+impl<D, E> fmt::Debug for UnsyncBoxBody<D, E> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("UnsyncBoxBody").finish()
+    }
+}
+
+impl<D, E> Body for UnsyncBoxBody<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) -> crate::SizeHint {
+        self.inner.size_hint()
+    }
+}
+
+impl<D, E> Default for UnsyncBoxBody<D, E>
+where
+    D: Buf + 'static,
+{
+    fn default() -> Self {
+        UnsyncBoxBody::new(crate::Empty::new().map_err(|err| match err {}))
+    }
+}

src/combinators/mod.rs

@@ -4,4 +4,8 @@ mod box_body;
 mod map_data;
 mod map_err;
 
-pub use self::{box_body::BoxBody, map_data::MapData, map_err::MapErr};
+pub use self::{
+    box_body::{BoxBody, UnsyncBoxBody},
+    map_data::MapData,
+    map_err::MapErr,
+};

src/lib.rs

@@ -25,7 +25,7 @@ pub use self::full::Full;
 pub use self::next::{Data, Trailers};
 pub use self::size_hint::SizeHint;
 
-use self::combinators::{BoxBody, MapData, MapErr};
+use self::combinators::{BoxBody, MapData, MapErr, UnsyncBoxBody};
 use bytes::Buf;
 use http::HeaderMap;
 use std::ops;
@@ -122,6 +122,14 @@ pub trait Body {
     {
         BoxBody::new(self)
     }
+
+    /// Turn this body into a boxed trait object that is !Sync.
+    fn boxed_unsync(self) -> UnsyncBoxBody<Self::Data, Self::Error>
+    where
+        Self: Sized + Send + 'static,
+    {
+        UnsyncBoxBody::new(self)
+    }
 }
 
 impl<T: Body + Unpin + ?Sized> Body for &mut T {