decoding fixed sized arrays

src/rlp/errors.rs

@@ -8,6 +8,7 @@ pub enum DecoderError {
 	RlpIsTooShort,
 	RlpExpectedToBeList,
 	RlpExpectedToBeData,
+	RlpIncorrectListLen
 }
 
 impl StdError for DecoderError {

src/rlp/tests.rs

@@ -343,3 +343,11 @@ fn test_rlp_json() {
 	});
 }
 
+#[test]
+fn test_decoding_array() {
+	let v = vec![5u16, 2u16];
+	let res = rlp::encode(&v);
+	let arr: [u16; 2] = rlp::decode(&res);
+	assert_eq!(arr[0], 5);
+	assert_eq!(arr[1], 2);
+}

src/rlp/untrusted_rlp.rs

@@ -352,3 +352,38 @@ impl<T> Decodable for Option<T> where T: Decodable {
 		})
 	}
 }
+
+macro_rules! impl_array_decodable {
+	($index_type:ty, $len:expr ) => (
+		impl<T> Decodable for [T; $len] where T: Decodable {
+			fn decode<D>(decoder: &D) -> Result<Self, DecoderError>  where D: Decoder {
+				decoder.read_list(| decoders | {
+					let mut result: [T; $len] = unsafe { ::std::mem::uninitialized() };
+					if decoders.len() != $len {
+						return Err(DecoderError::RlpIncorrectListLen);
+					}
+					
+					for i in 0..decoders.len() {
+						result[i] = try!(T::decode(&decoders[i]));
+					}
+
+					Ok(result)
+				})
+			}
+		}
+	)
+}
+
+macro_rules! impl_array_decodable_recursive {
+	($index_type:ty, ) => ();
+	($index_type:ty, $len:expr, $($more:expr,)*) => (
+		impl_array_decodable!($index_type, $len);
+		impl_array_decodable_recursive!($index_type, $($more,)*);
+	);
+}
+
+impl_array_decodable_recursive!(
+	u8, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
+	16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
+	32, 40, 48, 56, 64, 72, 96, 128, 160, 192, 224,
+);