implement Buf and BufMut for Either (#225)

src/either.rs

@@ -0,0 +1,89 @@
+extern crate either;
+
+use {Buf, BufMut};
+
+use self::either::Either;
+use self::either::Either::*;
+use iovec::IoVec;
+
+impl<L, R> Buf for Either<L, R>
+where
+    L: Buf,
+    R: Buf,
+{
+    fn remaining(&self) -> usize {
+        match *self {
+            Left(ref b) => b.remaining(),
+            Right(ref b) => b.remaining(),
+        }
+    }
+
+    fn bytes(&self) -> &[u8] {
+        match *self {
+            Left(ref b) => b.bytes(),
+            Right(ref b) => b.bytes(),
+        }
+    }
+
+    fn bytes_vec<'a>(&'a self, dst: &mut [&'a IoVec]) -> usize {
+        match *self {
+            Left(ref b) => b.bytes_vec(dst),
+            Right(ref b) => b.bytes_vec(dst),
+        }
+    }
+
+    fn advance(&mut self, cnt: usize) {
+        match *self {
+            Left(ref mut b) => b.advance(cnt),
+            Right(ref mut b) => b.advance(cnt),
+        }
+    }
+
+    fn copy_to_slice(&mut self, dst: &mut [u8]) {
+        match *self {
+            Left(ref mut b) => b.copy_to_slice(dst),
+            Right(ref mut b) => b.copy_to_slice(dst),
+        }
+    }
+}
+
+impl<L, R> BufMut for Either<L, R>
+where
+    L: BufMut,
+    R: BufMut,
+{
+    fn remaining_mut(&self) -> usize {
+        match *self {
+            Left(ref b) => b.remaining_mut(),
+            Right(ref b) => b.remaining_mut(),
+        }
+    }
+
+    unsafe fn bytes_mut(&mut self) -> &mut [u8] {
+        match *self {
+            Left(ref mut b) => b.bytes_mut(),
+            Right(ref mut b) => b.bytes_mut(),
+        }
+    }
+
+    unsafe fn bytes_vec_mut<'a>(&'a mut self, dst: &mut [&'a mut IoVec]) -> usize {
+        match *self {
+            Left(ref mut b) => b.bytes_vec_mut(dst),
+            Right(ref mut b) => b.bytes_vec_mut(dst),
+        }
+    }
+
+    unsafe fn advance_mut(&mut self, cnt: usize) {
+        match *self {
+            Left(ref mut b) => b.advance_mut(cnt),
+            Right(ref mut b) => b.advance_mut(cnt),
+        }
+    }
+
+    fn put_slice(&mut self, src: &[u8]) {
+        match *self {
+            Left(ref mut b) => b.put_slice(src),
+            Right(ref mut b) => b.put_slice(src),
+        }
+    }
+}

src/lib.rs

@@ -99,3 +99,7 @@ pub use byteorder::{ByteOrder, BigEndian, LittleEndian};
 #[cfg(feature = "serde")]
 #[doc(hidden)]
 pub mod serde;
+
+// Optional `Either` support
+#[cfg(feature = "either")]
+mod either;