fix: custom error enum

README.md

@@ -29,25 +29,25 @@ struct MemoryDBConfig;
 impl Database for MemoryDB {
     type Config = MemoryDBConfig;
 
-    fn new(_db_config: MemoryDBConfig) -> Result<Self> {
+    fn new(_db_config: MemoryDBConfig) -> PmtreeResult<Self> {
         Ok(MemoryDB(HashMap::new()))
     }
 
-    fn load(_db_config: MemoryDBConfig) -> Result<Self> {
-        Err(Box::new(Error("Cannot load in-memory DB".to_string())))
+    fn load(_db_config: MemoryDBConfig) -> PmtreeResult<Self> {
+        Err(DatabaseError(DatabaseErrorKind::CannotLoadDatabase))
     }
 
-    fn get(&self, key: DBKey) -> Result<Option<Value>> {
+    fn get(&self, key: DBKey) -> PmtreeResult<Option<Value>> {
         Ok(self.0.get(&key).cloned())
     }
 
-    fn put(&mut self, key: DBKey, value: Value) -> Result<()> {
+    fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()> {
         self.0.insert(key, value);
 
         Ok(())
     }
 
-    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> PmtreeResult<()> {
         self.0.extend(subtree.into_iter());
 
         Ok(())

src/database.rs

@@ -8,21 +8,21 @@ pub trait Database {
     type Config: Default;
 
     /// Creates new instance of db
-    fn new(config: Self::Config) -> Result<Self>
+    fn new(config: Self::Config) -> PmtreeResult<Self>
     where
         Self: Sized;
 
     /// Loades existing db (existence check required)
-    fn load(config: Self::Config) -> Result<Self>
+    fn load(config: Self::Config) -> PmtreeResult<Self>
     where
         Self: Sized;
 
     /// Returns value from db by the key
-    fn get(&self, key: DBKey) -> Result<Option<Value>>;
+    fn get(&self, key: DBKey) -> PmtreeResult<Option<Value>>;
 
     /// Puts the value to the db by the key
-    fn put(&mut self, key: DBKey, value: Value) -> Result<()>;
+    fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()>;
 
     /// Batc
-    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()>;
+    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> PmtreeResult<()>;
 }

src/lib.rs

@@ -20,17 +20,37 @@ pub type DBKey = [u8; 8];
 /// Denotes values in a database
 pub type Value = Vec<u8>;
 
-/// Denotes `Error` type, for handling DB interaction errors
 #[derive(Debug)]
-pub struct Error(pub String);
+pub enum TreeErrorKind {
+    MerkleTreeIsFull,
+    InvalidKey,
+    IndexOutOfBounds,
+}
 
-impl std::fmt::Display for Error {
+#[derive(Debug)]
+pub enum DatabaseErrorKind {
+    CannotLoadDatabase,
+    DatabaseExists,
+}
+
+#[derive(Debug)]
+pub enum PmtreeErrorKind {
+    /// Error in database
+    DatabaseError(DatabaseErrorKind),
+    /// Error in tree
+    TreeError(TreeErrorKind),
+}
+
+impl std::fmt::Display for PmtreeErrorKind {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
-        write!(f, "{}", self.0)
+        match self {
+            PmtreeErrorKind::DatabaseError(e) => write!(f, "Database error: {e:?}"),
+            PmtreeErrorKind::TreeError(e) => write!(f, "Tree error: {e:?}"),
+        }
     }
 }
 
-impl std::error::Error for Error {}
+impl std::error::Error for PmtreeErrorKind {}
 
 /// Custom `Result` type with custom `Error` type
-pub type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+pub type PmtreeResult<T> = std::result::Result<T, PmtreeErrorKind>;

src/tree.rs

@@ -44,12 +44,12 @@ where
     H: Hasher,
 {
     /// Creates tree with specified depth and default "pmtree_db" dbpath.
-    pub fn default(depth: usize) -> Result<Self> {
+    pub fn default(depth: usize) -> PmtreeResult<Self> {
         Self::new(depth, D::Config::default())
     }
 
     /// Creates new `MerkleTree` and store it to the specified path/db
-    pub fn new(depth: usize, db_config: D::Config) -> Result<Self> {
+    pub fn new(depth: usize, db_config: D::Config) -> PmtreeResult<Self> {
         // Create new db instance
         let mut db = D::new(db_config)?;
 
@@ -85,7 +85,7 @@ where
     }
 
     /// Loads existing Merkle Tree from the specified path/db
-    pub fn load(db_config: D::Config) -> Result<Self> {
+    pub fn load(db_config: D::Config) -> PmtreeResult<Self> {
         // Load existing db instance
         let db = D::load(db_config)?;
 
@@ -116,9 +116,9 @@ where
     }
 
     /// Sets a leaf at the specified tree index
-    pub fn set(&mut self, key: usize, leaf: H::Fr) -> Result<()> {
+    pub fn set(&mut self, key: usize, leaf: H::Fr) -> PmtreeResult<()> {
         if key >= self.capacity() {
-            return Err(Box::new(Error("Merkle Tree is full!".to_string())));
+            return Err(PmtreeErrorKind::TreeError(TreeErrorKind::IndexOutOfBounds));
         }
 
         self.db
@@ -136,7 +136,7 @@ where
     }
 
     // Recalculates `Merkle Tree` from the specified key
-    fn recalculate_from(&mut self, key: usize) -> Result<()> {
+    fn recalculate_from(&mut self, key: usize) -> PmtreeResult<()> {
         let mut depth = self.depth;
         let mut i = key;
 
@@ -156,7 +156,7 @@ where
     }
 
     // Hashes the correct couple for the key
-    fn hash_couple(&self, depth: usize, key: usize) -> Result<H::Fr> {
+    fn hash_couple(&self, depth: usize, key: usize) -> PmtreeResult<H::Fr> {
         let b = key & !1;
         Ok(H::hash(&[
             self.get_elem(Key(depth, b))?,
@@ -165,7 +165,7 @@ where
     }
 
     // Returns elem by the key
-    fn get_elem(&self, key: Key) -> Result<H::Fr> {
+    fn get_elem(&self, key: Key) -> PmtreeResult<H::Fr> {
         let res = self
             .db
             .get(key.into())?
@@ -175,9 +175,9 @@ where
     }
 
     /// Deletes a leaf at the `key` by setting it to its default value
-    pub fn delete(&mut self, key: usize) -> Result<()> {
+    pub fn delete(&mut self, key: usize) -> PmtreeResult<()> {
         if key >= self.next_index {
-            return Err(Box::new(Error("The key doesn't exist!".to_string())));
+            return Err(PmtreeErrorKind::TreeError(TreeErrorKind::InvalidKey));
         }
 
         self.set(key, H::default_leaf())?;
@@ -186,20 +186,18 @@ where
     }
 
     /// Inserts a leaf to the next available index
-    pub fn update_next(&mut self, leaf: H::Fr) -> Result<()> {
+    pub fn update_next(&mut self, leaf: H::Fr) -> PmtreeResult<()> {
         self.set(self.next_index, leaf)?;
 
         Ok(())
     }
 
     /// Batch insertion, updates the tree in parallel.
-    pub fn batch_insert(&mut self, leaves: &[H::Fr]) -> Result<()> {
+    pub fn batch_insert(&mut self, leaves: &[H::Fr]) -> PmtreeResult<()> {
         let end = self.next_index + leaves.len();
 
         if end > self.capacity() {
-            return Err(Box::new(Error(
-                "Not enough space to insert the leaves!".to_string(),
-            )));
+            return Err(PmtreeErrorKind::TreeError(TreeErrorKind::MerkleTreeIsFull));
         }
 
         let mut subtree = HashMap::<Key, H::Fr>::new();
@@ -253,7 +251,7 @@ where
         subtree: &mut HashMap<Key, H::Fr>,
         leaves: &[H::Fr],
         from: usize,
-    ) -> Result<()> {
+    ) -> PmtreeResult<()> {
         if key.0 == self.depth {
             if key.1 >= from {
                 subtree.insert(key, leaves[key.1 - from]);
@@ -309,9 +307,9 @@ where
     }
 
     /// Computes a Merkle proof for the leaf at the specified index
-    pub fn proof(&self, index: usize) -> Result<MerkleProof<H>> {
+    pub fn proof(&self, index: usize) -> PmtreeResult<MerkleProof<H>> {
         if index >= self.capacity() {
-            return Err(Box::new(Error("Index exceeds set size!".to_string())));
+            return Err(PmtreeErrorKind::TreeError(TreeErrorKind::IndexOutOfBounds));
         }
 
         let mut witness = Vec::with_capacity(self.depth);

tests/memory_keccak.rs

@@ -12,25 +12,25 @@ struct MemoryDBConfig;
 impl Database for MemoryDB {
     type Config = MemoryDBConfig;
 
-    fn new(_db_config: MemoryDBConfig) -> Result<Self> {
+    fn new(_db_config: MemoryDBConfig) -> PmtreeResult<Self> {
         Ok(MemoryDB(HashMap::new()))
     }
 
-    fn load(_db_config: MemoryDBConfig) -> Result<Self> {
-        Err(Box::new(Error("Cannot load in-memory DB".to_string())))
+    fn load(_db_config: MemoryDBConfig) -> PmtreeResult<Self> {
+        Err(DatabaseError(DatabaseErrorKind::CannotLoadDatabase))
     }
 
-    fn get(&self, key: DBKey) -> Result<Option<Value>> {
+    fn get(&self, key: DBKey) -> PmtreeResult<Option<Value>> {
         Ok(self.0.get(&key).cloned())
     }
 
-    fn put(&mut self, key: DBKey, value: Value) -> Result<()> {
+    fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()> {
         self.0.insert(key, value);
 
         Ok(())
     }
 
-    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> PmtreeResult<()> {
         self.0.extend(subtree.into_iter());
 
         Ok(())
@@ -64,7 +64,7 @@ impl Hasher for MyKeccak {
 }
 
 #[test]
-fn insert_delete() -> Result<()> {
+fn insert_delete() -> PmtreeResult<()> {
     let mut mt = MerkleTree::<MemoryDB, MyKeccak>::new(2, MemoryDBConfig)?;
 
     assert_eq!(mt.capacity(), 4);
@@ -110,7 +110,7 @@ fn insert_delete() -> Result<()> {
 }
 
 #[test]
-fn batch_insertions() -> Result<()> {
+fn batch_insertions() -> PmtreeResult<()> {
     let mut mt = MerkleTree::<MemoryDB, MyKeccak>::new(2, MemoryDBConfig)?;
 
     let leaves = [

tests/poseidon.rs

@@ -49,25 +49,25 @@ struct MemoryDBConfig;
 impl Database for MemoryDB {
     type Config = MemoryDBConfig;
 
-    fn new(_db_config: MemoryDBConfig) -> Result<Self> {
+    fn new(_db_config: MemoryDBConfig) -> PmtreeResult<Self> {
         Ok(MemoryDB(HashMap::new()))
     }
 
-    fn load(_db_config: MemoryDBConfig) -> Result<Self> {
-        Err(Box::new(Error("Cannot load in-memory DB".to_string())))
+    fn load(_db_config: MemoryDBConfig) -> PmtreeResult<Self> {
+        Err(DatabaseError(DatabaseErrorKind::CannotLoadDatabase))
     }
 
-    fn get(&self, key: DBKey) -> Result<Option<Value>> {
+    fn get(&self, key: DBKey) -> PmtreeResult<Option<Value>> {
         Ok(self.0.get(&key).cloned())
     }
 
-    fn put(&mut self, key: DBKey, value: Value) -> Result<()> {
+    fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()> {
         self.0.insert(key, value);
 
         Ok(())
     }
 
-    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> PmtreeResult<()> {
         self.0.extend(subtree.into_iter());
 
         Ok(())
@@ -82,33 +82,31 @@ struct SledConfig {
 impl Database for MySled {
     type Config = SledConfig;
 
-    fn new(db_config: SledConfig) -> Result<Self> {
+    fn new(db_config: SledConfig) -> PmtreeResult<Self> {
         let db = sled::open(db_config.path).unwrap();
         if db.was_recovered() {
-            return Err(Box::new(Error("Database exists, try load()!".to_string())));
+            return Err(DatabaseError(DatabaseErrorKind::DatabaseExists));
         }
 
         Ok(MySled(db))
     }
 
-    fn load(db_config: SledConfig) -> Result<Self> {
+    fn load(db_config: SledConfig) -> PmtreeResult<Self> {
         let db = sled::open(&db_config.path).unwrap();
 
         if !db.was_recovered() {
             fs::remove_dir_all(&db_config.path).expect("Error removing db");
-            return Err(Box::new(Error(
-                "Trying to load non-existing database!".to_string(),
-            )));
+            return Err(DatabaseError(DatabaseErrorKind::CannotLoadDatabase));
         }
 
         Ok(MySled(db))
     }
 
-    fn get(&self, key: DBKey) -> Result<Option<Value>> {
+    fn get(&self, key: DBKey) -> PmtreeResult<Option<Value>> {
         Ok(self.0.get(key).unwrap().map(|val| val.to_vec()))
     }
 
-    fn put(&mut self, key: DBKey, value: Value) -> Result<()> {
+    fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()> {
         self.0.insert(key, value).unwrap();
 
         self.0.flush().unwrap();
@@ -116,7 +114,7 @@ impl Database for MySled {
         Ok(())
     }
 
-    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> PmtreeResult<()> {
         let mut batch = sled::Batch::default();
 
         for (key, value) in subtree {
@@ -130,7 +128,7 @@ impl Database for MySled {
 }
 
 #[test]
-fn poseidon_memory() -> Result<()> {
+fn poseidon_memory() -> PmtreeResult<()> {
     let mut mt = MerkleTree::<MemoryDB, PoseidonHash>::new(TEST_TREE_HEIGHT, MemoryDBConfig)?;
 
     let leaf_index = 3;
@@ -254,7 +252,7 @@ fn poseidon_memory() -> Result<()> {
 }
 
 #[test]
-fn poseidon_sled() -> Result<()> {
+fn poseidon_sled() -> PmtreeResult<()> {
     let mut mt = MerkleTree::<MySled, PoseidonHash>::new(
         TEST_TREE_HEIGHT,
         SledConfig {

tests/sled_keccak.rs

@@ -15,33 +15,31 @@ struct SledConfig {
 impl Database for MySled {
     type Config = SledConfig;
 
-    fn new(db_config: SledConfig) -> Result<Self> {
+    fn new(db_config: SledConfig) -> PmtreeResult<Self> {
         let db = sled::open(db_config.path).unwrap();
         if db.was_recovered() {
-            return Err(Box::new(Error("Database exists, try load()!".to_string())));
+            return Err(DatabaseError(DatabaseErrorKind::DatabaseExists));
         }
 
         Ok(MySled(db))
     }
 
-    fn load(db_config: SledConfig) -> Result<Self> {
+    fn load(db_config: SledConfig) -> PmtreeResult<Self> {
         let db = sled::open(&db_config.path).unwrap();
 
         if !db.was_recovered() {
             fs::remove_dir_all(&db_config.path).expect("Error removing db");
-            return Err(Box::new(Error(
-                "Trying to load non-existing database!".to_string(),
-            )));
+            return Err(DatabaseError(DatabaseErrorKind::CannotLoadDatabase));
         }
 
         Ok(MySled(db))
     }
 
-    fn get(&self, key: DBKey) -> Result<Option<Value>> {
+    fn get(&self, key: DBKey) -> PmtreeResult<Option<Value>> {
         Ok(self.0.get(key).unwrap().map(|val| val.to_vec()))
     }
 
-    fn put(&mut self, key: DBKey, value: Value) -> Result<()> {
+    fn put(&mut self, key: DBKey, value: Value) -> PmtreeResult<()> {
         self.0.insert(key, value).unwrap();
 
         self.0.flush().unwrap();
@@ -49,7 +47,7 @@ impl Database for MySled {
         Ok(())
     }
 
-    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> Result<()> {
+    fn put_batch(&mut self, subtree: HashMap<DBKey, Value>) -> PmtreeResult<()> {
         let mut batch = sled::Batch::default();
 
         for (key, value) in subtree {
@@ -89,7 +87,7 @@ impl Hasher for MyKeccak {
 }
 
 #[test]
-fn insert_delete() -> Result<()> {
+fn insert_delete() -> PmtreeResult<()> {
     let mut mt = MerkleTree::<MySled, MyKeccak>::new(
         2,
         SledConfig {
@@ -142,7 +140,7 @@ fn insert_delete() -> Result<()> {
 }
 
 #[test]
-fn batch_insertions() -> Result<()> {
+fn batch_insertions() -> PmtreeResult<()> {
     let mut mt = MerkleTree::<MySled, MyKeccak>::new(
         2,
         SledConfig {