feat: add new/load function for the Merkle Tree

src/database.rs

@@ -2,8 +2,14 @@ use crate::*;
 
 /// Trait that must be implemented for a Database
 pub trait Database {
+    /// Creates new instance of db
     fn new(dbpath: &str) -> Self;
-    fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>>;
-    fn put(&mut self, key: &[u8], value: &[u8]) -> Result<()>;
-    fn delete(&mut self, key: &[u8]) -> Result<()>;
+    /// Loades existing db (existence check required)
+    fn load(dbpath: &str) -> Self;
+    /// Returns value from db by the key
+    fn get(&self, key: DBKey) -> Result<Option<Value>>;
+    /// Puts the value to the db by the key
+    fn put(&mut self, key: DBKey, value: Value) -> Result<()>;
+    /// Deletes the key from db
+    fn delete(&mut self, key: DBKey) -> Result<()>;
 }

src/hasher.rs

@@ -1,12 +1,14 @@
-pub trait ToBytes {
-    fn to_bytes(&self) -> Vec<u8>;
-}
+use crate::*;
 
 /// Trait that must be implemented for Hash Function
 pub trait Hasher {
-    type Fr: Copy + Eq + Default + From<Vec<u8>> + Into<Vec<u8>>;
+    /// Native type for the hash-function
+    type Fr: Copy + Eq + Default + From<Value> + Into<Value>;
 
+    /// Creates new hash-function instance
     fn new() -> Self;
+    /// Outputs the default leaf (Fr::default())
     fn default_leaf() -> Self::Fr;
+    /// Calculates hash-function
     fn hash(input: &[Self::Fr]) -> Self::Fr;
 }

src/lib.rs

@@ -1,5 +1,5 @@
 //! # pmtree
-//! Persistent Merkle tree in Rust
+//! Persistent Merkle Tree in Rust
 
 pub mod database;
 pub mod hasher;
@@ -9,11 +9,15 @@ pub use database::*;
 pub use hasher::*;
 pub use tree::MerkleTree;
 
-/// Type denoting errors that occur when interacting
-/// with Database
+/// Denotes errors that occur when interacting with Database
 #[derive(Debug)]
 pub struct Error(String);
 
-/// Custom `Result` type/alias; used for interaction
-/// with Database
+/// Custom `Result` type/alias; used for interaction with Database
 pub type Result<T> = std::result::Result<T, Error>;
+
+/// Denotes keys in a database
+pub type DBKey = [u8; 32];
+
+/// Denotes values in a database
+pub type Value = Vec<u8>;

src/tree.rs

@@ -1,5 +1,6 @@
 use crate::*;
 
+/// Merkle Tree implementation
 pub struct MerkleTree<D, H>
 where
     D: Database,
@@ -11,39 +12,19 @@ where
     next_index: usize,
 }
 
-pub(crate) struct Key(usize, usize);
-
-impl From<Key> for Vec<u8> {
-    fn from(key: Key) -> Vec<u8> {
-        todo!()
-    }
-}
-
 impl<D, H> MerkleTree<D, H>
 where
     D: Database,
     H: Hasher,
 {
-    /// Creates new `MerkleTree`
+    /// Creates new `MerkleTree` and store it to the specified path/db
     pub fn new(depth: usize, dbpath: &str) -> Result<Self> {
-        // TODO: Use open instead of new, and check if the database is exists
-        let mut db: D = Database::new(dbpath);
+        todo!()
+    }
 
-        db.put(&Vec::<u8>::from(Key(depth, 0)), &H::default_leaf().into())?;
-        for i in (0..depth).rev() {
-            let prev = db.get(&Vec::<u8>::from(Key(i + 1, 0)))?.unwrap();
-            db.put(
-                &Vec::<u8>::from(Key(i, 0)),
-                &H::hash(&[prev.clone().into(), prev.into()]).into(),
-            )?;
-        }
-
-        Ok(Self {
-            db,
-            h: Hasher::new(),
-            depth,
-            next_index: 0,
-        })
+    /// Loads existing Merkle Tree from the specified path/db
+    pub fn load(dbpath: &str) -> Result<Self> {
+        todo!()
     }
 
     /// Inserts a leaf to the next available index
@@ -51,7 +32,7 @@ where
         todo!()
     }
 
-    /// Recalculates `Merkle Tree` from the specified key
+    // Recalculates `Merkle Tree` from the specified key
     fn recalculate_from(&mut self, key: usize) {
         todo!()
     }