Merge pull request #8 from gavofyork/rlp_lifetimes

rlp lifetimes

src/rlp.rs

@@ -132,7 +132,7 @@ pub enum Prototype {
 	List(usize),
 }
 
-impl<'a> Rlp<'a> {
+impl<'a, 'view> Rlp<'a> where 'a: 'view {
 	/// Create a new instance of `Rlp`
 	pub fn new(bytes: &'a [u8]) -> Rlp<'a> {
 		Rlp {
@@ -162,12 +162,11 @@ impl<'a> Rlp<'a> {
 	/// fn main () {
 	/// 	let data = vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g'];
 	/// 	let rlp = Rlp::new(&data);
-	/// 	let view = rlp.at(1);
+	/// 	let dog = rlp.at(1).data();
-	/// 	let dog = view.data();
 	/// 	assert_eq!(dog, &[0x83, b'd', b'o', b'g']);
 	/// }
 	/// ```
-	pub fn data(&self) -> &[u8] {
+	pub fn data(&'view self) -> &'a [u8] {
 		self.rlp.data()
 	}
 
@@ -223,7 +222,7 @@ impl<'a> Rlp<'a> {
 	/// 	assert_eq!(dog, "dog".to_string());
 	/// }
 	/// ```
-	pub fn at(&self, index: usize) -> Rlp<'a> {
+	pub fn at(&'view self, index: usize) -> Rlp<'a> {
 		From::from(self.rlp.at(index).unwrap())
 	}
 
@@ -325,7 +324,7 @@ impl<'a> Rlp<'a> {
 	}
 }
 
-impl<'a> UntrustedRlp<'a> {
+impl<'a, 'view> UntrustedRlp<'a> where 'a: 'view {
 	/// returns new instance of `UntrustedRlp`
 	pub fn new(bytes: &'a [u8]) -> UntrustedRlp<'a> {
 		UntrustedRlp {
@@ -343,12 +342,11 @@ impl<'a> UntrustedRlp<'a> {
 	/// fn main () {
 	/// 	let data = vec![0xc8, 0x83, b'c', b'a', b't', 0x83, b'd', b'o', b'g'];
 	/// 	let rlp = UntrustedRlp::new(&data);
-	/// 	let view = rlp.at(1).unwrap();
+	/// 	let dog = rlp.at(1).unwrap().data();
-	/// 	let dog = view.data();
 	/// 	assert_eq!(dog, &[0x83, b'd', b'o', b'g']);
 	/// }
 	/// ```
-	pub fn data(&self) -> &[u8] {
+	pub fn data(&'view self) -> &'a [u8] {
 		self.bytes
 	}
 
@@ -410,7 +408,7 @@ impl<'a> UntrustedRlp<'a> {
 	/// 	assert_eq!(dog, "dog".to_string());
 	/// }
 	/// ```
-	pub fn at(&self, index: usize) -> Result<UntrustedRlp<'a>, DecoderError> {
+	pub fn at(&'view self, index: usize) -> Result<UntrustedRlp<'a>, DecoderError> {
 		if !self.is_list() {
 			return Err(DecoderError::RlpExpectedToBeList);
 		}
@@ -1452,4 +1450,31 @@ mod tests {
 								   vec![0xc5, 0xc4, 0x83, b'c', b'a', b't'])];
 		run_decode_tests(tests);
 	}
+
+	#[test]
+	fn test_view() {
+		struct View<'a> {
+			bytes: &'a [u8]
+		}
+
+		impl <'a, 'view> View<'a> where 'a: 'view {
+			fn new(bytes: &'a [u8]) -> View<'a> {
+				View {
+					bytes: bytes
+				}
+			}
+
+			fn offset(&'view self, len: usize) -> View<'a> {
+				View::new(&self.bytes[len..])
+			}
+
+			fn data(&'view self) -> &'a [u8] {
+				self.bytes
+			}
+		}
+
+		let data = vec![0, 1, 2, 3];
+		let view = View::new(&data);
+		let _data_slice = view.offset(1).data();
+	}
 }

src/triehash.rs

@@ -138,9 +138,9 @@ fn as_nibbles(bytes: &[u8]) -> Vec<u8> {
 fn hash256rlp(input: &[(Vec<u8>, Vec<u8>)], pre_len: usize, stream: &mut RlpStream) {
 	let inlen = input.len();
 
-	// in case of empty slice, just append null
+	// in case of empty slice, just append empty data
 	if inlen == 0 {
-		stream.append(&""); 
+		stream.append_empty_data();
 		return;
 	}
 
@@ -196,7 +196,7 @@ fn hash256rlp(input: &[(Vec<u8>, Vec<u8>)], pre_len: usize, stream: &mut RlpStre
 		// if at least 1 successive element has the same nibble
 		// append their suffixes
 		match len {
-			0 => { stream.append(&""); },
+			0 => { stream.append_empty_data(); },
 			_ => hash256aux(&input[begin..(begin + len)], pre_len + 1, stream)
 		}
 		begin += len;
@@ -205,7 +205,7 @@ fn hash256rlp(input: &[(Vec<u8>, Vec<u8>)], pre_len: usize, stream: &mut RlpStre
 	// if fist key len is equal prefix, append it's value
 	match pre_len == key.len() {
 		true => { stream.append(&value); },
-		false => { stream.append(&""); }
+		false => { stream.append_empty_data(); }
 	};
 }