The Reader can implement BufReader naturally (#232)

There's no reason the user should be forced to wrap it in BufReader in
case the trait is needed, because the Reader has all the bits for
supporting it naturally.

src/buf/reader.rs

@@ -86,3 +86,12 @@ impl<B: Buf + Sized> io::Read for Reader<B> {
         Ok(len)
     }
 }
+
+impl<B: Buf + Sized> io::BufRead for Reader<B> {
+    fn fill_buf(&mut self) -> io::Result<&[u8]> {
+        Ok(self.buf.bytes())
+    }
+    fn consume(&mut self, amt: usize) {
+        self.buf.advance(amt)
+    }
+}

tests/test_reader.rs

+extern crate bytes;
+
+use std::io::{BufRead, Cursor, Read};
+
+use bytes::Buf;
+
+#[test]
+fn read() {
+    let buf1 = Cursor::new(b"hello ");
+    let buf2 = Cursor::new(b"world");
+    let buf = Buf::chain(buf1, buf2); // Disambiguate with Read::chain
+    let mut buffer = Vec::new();
+    buf.reader().read_to_end(&mut buffer).unwrap();
+    assert_eq!(b"hello world", &buffer[..]);
+}
+
+#[test]
+fn buf_read() {
+    let buf1 = Cursor::new(b"hell");
+    let buf2 = Cursor::new(b"o\nworld");
+    let mut reader = Buf::chain(buf1, buf2).reader();
+    let mut line = String::new();
+    reader.read_line(&mut line).unwrap();
+    assert_eq!("hello\n", &line);
+    line.clear();
+    reader.read_line(&mut line).unwrap();
+    assert_eq!("world", &line);
+}