Add associated method to DecodeLimit for advancing input index (#286)

* Add associated method to DecodeLimit for advancing input index

* Run cargo update

* remove flacky test false positive

* Disable another flaky test

* Disable yet another flaky test

* Bump version to 2.3.0

Co-authored-by: thiolliere <gui.thiolliere@gmail.com>

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this crate are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this crate adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [2.3.0] - 2021-09-11
+
+### Added
+- `decode_and_advance_with_depth_limit` to the `DecodeLimit` trait. This allows advancing the cursor while decoding the input. PR #286
+
 ## [2.2.0] - 2021-07-02
 
 ### Added

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "parity-scale-codec"
 description = "SCALE - Simple Concatenating Aggregated Little Endians"
-version = "2.2.0"
+version = "2.3.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 repository = "https://github.com/paritytech/parity-scale-codec"

derive/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "parity-scale-codec-derive"
 description = "Serialization and deserialization derive macro for Parity SCALE Codec"
-version = "2.2.0"
+version = "2.3.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 license = "Apache-2.0"
 edition = "2018"

src/bit_vec.rs

@@ -178,6 +178,11 @@ mod tests {
 	}
 
 	#[test]
+	// Flaky test due to:
+	// * https://github.com/bitvecto-rs/bitvec/issues/135
+	// * https://github.com/rust-lang/miri/issues/1866
+	#[cfg(not(miri))]
+
 	fn bitvec_u16() {
 		for v in &test_data!(u16) {
 			let encoded = v.encode();
@@ -194,6 +199,11 @@ mod tests {
 	}
 
 	#[test]
+	// Flaky test due to:
+	// * https://github.com/bitvecto-rs/bitvec/issues/135
+	// * https://github.com/rust-lang/miri/issues/1866
+	#[cfg(not(miri))]
+
 	fn bitvec_u64() {
 		for v in &test_data!(u64) {
 			let encoded = v.encode();
@@ -211,6 +221,10 @@ mod tests {
 	}
 
 	#[test]
+	// Flaky test due to:
+	// * https://github.com/bitvecto-rs/bitvec/issues/135
+	// * https://github.com/rust-lang/miri/issues/1866
+	#[cfg(not(miri))]
 	fn bitbox() {
 		let data: &[u8] = &[5, 10];
 		let slice = BitSlice::<Msb0, u8>::from_slice(data).unwrap();

src/depth_limit.rs

@@ -24,6 +24,11 @@ pub trait DecodeLimit: Sized {
 	/// If `limit` is hit, an error is returned.
 	fn decode_with_depth_limit(limit: u32, input: &[u8]) -> Result<Self, Error>;
 
+	/// Decode `Self` and advance `input` by the number of bytes consumed.
+	///
+	/// If `limit` is hit, an error is returned.
+	fn decode_and_advance_with_depth_limit<I: Input>(limit: u32, input: &mut I) -> Result<Self, Error>;
+
 	/// Decode `Self` and consume all of the given input data.
 	///
 	/// If not all data is consumed or `limit` is hit, an error is returned.
@@ -82,6 +87,15 @@ impl<T: Decode> DecodeLimit for T {
 		}
 	}
 
+	fn decode_and_advance_with_depth_limit<I: Input>(limit: u32, input: &mut I) -> Result<Self, Error> {
+		let mut input = DepthTrackingInput {
+			input,
+			depth: 0,
+			max_depth: limit,
+		};
+		T::decode(&mut input)
+	}
+
 	fn decode_with_depth_limit(limit: u32, input: &[u8]) -> Result<Self, Error> {
 		let mut input = DepthTrackingInput {
 			input: &mut &input[..],
@@ -107,4 +121,15 @@ mod tests {
 		assert_eq!(decoded, nested);
 		assert!(NestedVec::decode_with_depth_limit(2, &encoded).is_err());
 	}
+
+	#[test]
+	fn decode_and_advance_works() {
+		type NestedVec = Vec<Vec<Vec<Vec<u8>>>>;
+		let nested: NestedVec = vec![vec![vec![vec![1]]]];
+		let encoded = &mut &nested.encode()[..];
+
+		let decoded = Vec::<u8>::decode_and_advance_with_depth_limit(1, encoded).unwrap();
+		assert_eq!(decoded, vec![4]);
+		assert!(NestedVec::decode_with_depth_limit(3, encoded).is_err());
+	}
 }