feat(smt): export get_value() in the trait

src/merkle/smt/full/mod.rs

@@ -121,12 +121,7 @@ impl Smt {
 
     /// Returns the value associated with `key`
     pub fn get_value(&self, key: &RpoDigest) -> Word {
-        let leaf_pos = LeafIndex::<SMT_DEPTH>::from(*key).value();
-
-        match self.leaves.get(&leaf_pos) {
-            Some(leaf) => leaf.get_value(key).unwrap_or_default(),
-            None => EMPTY_WORD,
-        }
+        <Self as SparseMerkleTree<SMT_DEPTH>>::get_value(self, key)
     }
 
     /// Returns an opening of the leaf associated with `key`. Conceptually, an opening is a Merkle
@@ -250,6 +245,15 @@ impl SparseMerkleTree<SMT_DEPTH> for Smt {
         }
     }
 
+    fn get_value(&self, key: &Self::Key) -> Self::Value {
+        let leaf_pos = LeafIndex::<SMT_DEPTH>::from(*key).value();
+
+        match self.leaves.get(&leaf_pos) {
+            Some(leaf) => leaf.get_value(key).unwrap_or_default(),
+            None => EMPTY_WORD,
+        }
+    }
+
     fn get_leaf(&self, key: &RpoDigest) -> Self::Leaf {
         let leaf_pos = LeafIndex::<SMT_DEPTH>::from(*key).value();
 

src/merkle/smt/mod.rs

@@ -161,6 +161,10 @@ pub(crate) trait SparseMerkleTree<const DEPTH: u8> {
     /// Inserts a leaf node, and returns the value at the key if already exists
     fn insert_value(&mut self, key: Self::Key, value: Self::Value) -> Option<Self::Value>;
 
+    /// Returns the value at the specified key. Recall that by definition, any key that hasn't been
+    /// updated is associated with [`Self::EMPTY_VALUE`].
+    fn get_value(&self, key: &Self::Key) -> Self::Value;
+
     /// Returns the leaf at the specified index.
     fn get_leaf(&self, key: &Self::Key) -> Self::Leaf;
 

src/merkle/smt/simple/mod.rs

@@ -289,6 +289,10 @@ impl<const DEPTH: u8> SparseMerkleTree<DEPTH> for SimpleSmt<DEPTH> {
         }
     }
 
+    fn get_value(&self, key: &LeafIndex<DEPTH>) -> Word {
+        self.get_leaf(key)
+    }
+
     fn get_leaf(&self, key: &LeafIndex<DEPTH>) -> Word {
         let leaf_pos = key.value();
         match self.leaves.get(&leaf_pos) {