WIP: smt: factor out MerklePath logic

src/merkle/smt/mod.rs

@@ -79,17 +79,15 @@ pub(crate) trait SparseMerkleTree<const DEPTH: u8> {
     // PROVIDED METHODS
     // ---------------------------------------------------------------------------------------------
 
-    /// Returns an opening of the leaf associated with `key`. Conceptually, an opening is a Merkle
+    /// Returns a [`MerklePath`] to the specified key.
-    /// path to the leaf, as well as the leaf itself.
+    ///
-    fn open(&self, key: &Self::Key) -> Self::Opening {
+    /// Mostly this is an implementation detail of [`Self::open()`].
-        let leaf = self.get_leaf(key);
+    fn path(&self, key: &Self::Key) -> MerklePath {
-
         let mut index: NodeIndex = {
             let leaf_index: LeafIndex<DEPTH> = Self::key_to_leaf_index(key);
             leaf_index.into()
         };
 
-        let merkle_path = {
         let mut path = Vec::with_capacity(index.depth() as usize);
         for _ in 0..index.depth() {
             let is_right = index.is_value_odd();
@@ -100,7 +98,13 @@ pub(crate) trait SparseMerkleTree<const DEPTH: u8> {
         }
 
         MerklePath::new(path)
-        };
+    }
+
+    /// Returns an opening of the leaf associated with `key`. Conceptually, an opening is a Merkle
+    /// path to the leaf, as well as the leaf itself.
+    fn open(&self, key: &Self::Key) -> Self::Opening {
+        let leaf = self.get_leaf(key);
+        let merkle_path = self.path(key);
 
         Self::path_and_leaf_to_opening(merkle_path, leaf)
     }