def test_can_create_new_function(self):
# Create a square function (which will be added to the environment)
env = Environment()
square_function = "(defun square(x)(* x x)))"
Evaluator.evaluate(Parser.parse(Tokenizer.tokenize(square_function)), env)
self.assertTrue(env.get("square"))
# Call the square function
call_square_function = "(square 9)"
returned_value = Evaluator.evaluate(Parser.parse(Tokenizer.tokenize(call_square_function)), env)
self.assertEqual(returned_value, 81)
def test_can_lookup_variable_from_the_environment(self):
env = Environment()
env.set("a", 2.0)
env.set("b", 3.0)
parse_tree = [ OperatorFactory.make_operator("*"), Symbol("a"), Symbol("b") ]
result = Evaluator.evaluate(parse_tree, env)
self.assertEqual(result, 6.0)
def test_can_handle_nested_arithmetic(self):
parse_tree = [ OperatorFactory.make_operator("*"),
Number(2.0),
[ OperatorFactory.make_operator("+"), Number(4.0), Number(5.0) ] ]
result = Evaluator.evaluate(parse_tree)
self.assertEqual(result, 18.0)
def test_can_evaluate_simple_subtraction(self):
parse_tree = [ OperatorFactory.make_operator("-"), Number(8.0), Number(4.0), Number(1.0) ]
result = Evaluator.evaluate(parse_tree)
self.assertEqual(result, 3.0)
def test_can_evaluate_simple_division(self):
parse_tree = [ OperatorFactory.make_operator("/"), Number(8.0), Number(2.0) ]
result = Evaluator.evaluate(parse_tree)
self.assertEqual(result, 4.0)
def test_can_evaluate_simple_addition(self):
parse_tree = [ OperatorFactory.make_operator("+"), Number(2.0), Number(3.0) ]
result = Evaluator.evaluate(parse_tree)
self.assertEqual(result, 5.0)
def test_can_set_variable_to_the_environment(self):
env = Environment()
parse_tree = [ OperatorFactory.make_operator("set!"), Symbol("x"), Number(19) ]
Evaluator.evaluate(parse_tree, env)
self.assertEqual(env.get("x"), 19)