Add tree.Get

tree.go

@@ -434,8 +434,22 @@ func bytesToBitmap(b []byte) []bool {
 
 // Get returns the value for a given key
 func (t *Tree) Get(k []byte) ([]byte, []byte, error) {
-	// unimplemented
-	return nil, nil, fmt.Errorf("unimplemented")
+	keyPath := make([]byte, t.hashFunction.Len())
+	copy(keyPath[:], k)
+
+	path := getPath(t.maxLevels, keyPath)
+	// go down to the leaf
+	var siblings [][]byte
+	_, value, _, err := t.down(k, t.root, siblings, path, 0, true)
+	if err != nil {
+		return nil, nil, err
+	}
+	leafK, leafV := readLeafValue(value)
+	if !bytes.Equal(k, leafK) {
+		panic(fmt.Errorf("%s != %s", BytesToBigInt(k), BytesToBigInt(leafK)))
+	}
+
+	return leafK, leafV, nil
 }
 
 // CheckProof verifies the given proof. The proof verification depends on the

tree_test.go

@@ -145,6 +145,26 @@ func TestAux(t *testing.T) {
 	assert.Nil(t, err)
 }
 
+func TestGet(t *testing.T) {
+	tree, err := NewTree(memory.NewMemoryStorage(), 100, HashFunctionPoseidon)
+	require.Nil(t, err)
+
+	defer tree.db.Close()
+	for i := 0; i < 10; i++ {
+		k := BigIntToBytes(big.NewInt(int64(i)))
+		v := BigIntToBytes(big.NewInt(int64(i * 2)))
+		if err := tree.Add(k, v); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	k := BigIntToBytes(big.NewInt(int64(7)))
+	gettedKey, gettedValue, err := tree.Get(k)
+	assert.Nil(t, err)
+	assert.Equal(t, k, gettedKey)
+	assert.Equal(t, BigIntToBytes(big.NewInt(int64(7*2))), gettedValue)
+}
+
 func TestGenProofAndVerify(t *testing.T) {
 	tree, err := NewTree(memory.NewMemoryStorage(), 100, HashFunctionPoseidon)
 	require.Nil(t, err)