SparseMerklePath: implement Serializable and Deserializable

src/merkle/sparse_path.rs

@@ -196,6 +196,29 @@ impl DoubleEndedIterator for SparseMerkleIter {
     }
 }
 
+// SERIALIZATION
+// ================================================================================================
+
+impl Serializable for SparseMerklePath {
+    fn write_into<W: winter_utils::ByteWriter>(&self, target: &mut W) {
+        target.write_u8(self.depth());
+        target.write_u64(self.empty_nodes);
+        target.write_many(&self.nodes);
+    }
+}
+
+impl Deserializable for SparseMerklePath {
+    fn read_from<R: winter_utils::ByteReader>(
+        source: &mut R,
+    ) -> Result<Self, DeserializationError> {
+        let depth = source.read_u8()?;
+        let empty_nodes = source.read_u64()?;
+        let count = depth as u32 - empty_nodes.count_ones();
+        let nodes = source.read_many::<RpoDigest>(count as usize)?;
+        Ok(Self { empty_nodes, nodes })
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use alloc::vec::Vec;