calculator successfully updated by agent

calculator/pkg/calculator.py

@@ -16,15 +16,36 @@ class Calculator:
     def evaluate(self, expression):
         if not expression or expression.isspace():
             return None
-        tokens = expression.strip().split()
+        tokens = self._tokenize(expression)
         return self._evaluate_infix(tokens)
 
+    def _tokenize(self, expression):
+        # Add spaces around operators and parentheses for easy splitting
+        expression = (
+            expression.replace("(", " ( ")
+            .replace(")", " ) ")
+            .replace("+", " + ")
+            .replace("-", " - ")
+            .replace("*", " * ")
+            .replace("/", " / ")
+        )
+        return [token for token in expression.split() if token]
+
     def _evaluate_infix(self, tokens):
         values = []
         operators = []
 
         for token in tokens:
-            if token in self.operators:
+            if token == "(":
+                operators.append(token)
+            elif token == ")":
+                while operators and operators[-1] != "(":
+                    self._apply_operator(operators, values)
+                if operators and operators[-1] == "(":
+                    operators.pop()  # Pop the opening parenthesis
+                else:
+                    raise ValueError("Mismatched parentheses")
+            elif token in self.operators:
                 while (
                     operators
                     and operators[-1] in self.operators
@@ -39,6 +60,8 @@ class Calculator:
                     raise ValueError(f"invalid token: {token}")
 
         while operators:
+            if operators[-1] == "(":
+                raise ValueError("Mismatched parentheses")
             self._apply_operator(operators, values)
 
         if len(values) != 1: