Exemple #1
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 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)
Exemple #2
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    def test_throws_exception_when_getting_unbound(self):
        env = Environment()
        with self.assertRaises(Exception) as context:
            env.get("a")
        self.assertEqual(str(context.exception), 'Unbound variable: a')

        with self.assertRaises(Exception) as context:
            env.get("b")
        self.assertEqual(str(context.exception), 'Unbound variable: b')
Exemple #3
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    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)
Exemple #4
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 def test_getting_and_setting_variable(self):
     env = Environment()
     value = 2.3
     env.set("a", value)
     self.assertEqual(value, env.get("a"))
Exemple #5
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 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)