rlp encodable and decodable for options

src/rlp/mod.rs

@@ -74,8 +74,7 @@ pub fn decode<T>(bytes: &[u8]) -> T where T: Decodable {
 /// 	assert_eq!(out, vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g']);
 /// }
 /// ```
-pub fn encode<E>(object: &E) -> Vec<u8> where E: Encodable
-{
+pub fn encode<E>(object: &E) -> Vec<u8> where E: Encodable {
 	let mut stream = RlpStream::new();
 	stream.append(object);
 	stream.out()

src/rlp/rlpstream.rs

@@ -207,13 +207,13 @@ impl Encoder for BasicEncoder {
 }
 
 impl<T> Encodable for T where T: ToBytes {
-	fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
 		encoder.emit_value(&self.to_bytes())
 	}
 }
 
 impl<'a, T> Encodable for &'a [T] where T: Encodable + 'a {
-	fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
 		encoder.emit_list(|e| {
 			// insert all list elements
 			for el in self.iter() {
@@ -224,7 +224,7 @@ impl<'a, T> Encodable for &'a [T] where T: Encodable + 'a {
 }
 
 impl<T> Encodable for Vec<T> where T: Encodable {
-	fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
 		let r: &[T] = self.as_ref();
 		r.encode(encoder)
 	}
@@ -233,7 +233,7 @@ impl<T> Encodable for Vec<T> where T: Encodable {
 /// lets treat bytes differently than other lists
 /// they are a single value
 impl<'a> Encodable for &'a [u8] {
-	fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
 		encoder.emit_value(self)
 	}
 }
@@ -241,7 +241,16 @@ impl<'a> Encodable for &'a [u8] {
 /// lets treat bytes differently than other lists
 /// they are a single value
 impl Encodable for Vec<u8> {
-	fn encode<E>(&self, encoder: &mut E) -> () where E: Encoder {
+	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
 		encoder.emit_value(self)
 	}
 }
+
+impl<T> Encodable for Option<T> where T: Encodable {
+	fn encode<E>(&self, encoder: &mut E) where E: Encoder {
+		match *self {
+			Some(ref x) => x.encode(encoder),
+			None => encoder.emit_value(&[])
+		}
+	}
+}

src/rlp/untrusted_rlp.rs

@@ -340,3 +340,15 @@ impl Decodable for Vec<u8> {
 		})
 	}
 }
+
+impl<T> Decodable for Option<T> where T: Decodable {
+	fn decode<D>(decoder: &D) -> Result<Self, DecoderError>  where D: Decoder {
+		decoder.read_value(| bytes | {
+			let res = match bytes.len() {
+				0 => None,
+				_ => Some(try!(T::decode(decoder)))
+			};
+			Ok(res)
+		})
+	}
+}