def brackets_match(string):
"""Check if all brackets in the string are correctly matched.
Return True if they are, otherwise False.
Only consider round and square brackets, i.e. () and []. For example:
>>> brackets_match("No brackets is fine")
True
>>> brackets_match("After ( and [ comes ] and )")
True
>>> brackets_match("After ( and [ it cannot be ) and ]")
False
>>> brackets_match("A ( without closing bracket")
False
>>> brackets_match("A ] without opening bracket")
False
>>> brackets_match("Snarks are rarely seen (according to Smith (1999)).")
True
"""
expected = Stack()
for character in string:
if character == "(":
expected.push(")")
elif character == "[":
expected.push("]")
elif character == ")" or character == "]":
if expected and character == expected.top():
expected.pop()
else:
return False
return expected.is_empty()
class TestStack(unittest.TestCase):
def setUp(self):
# Create stacks for the tests to use
self.new = Stack()
self.empty = Stack()
self.empty.push('hi')
self.empty.pop()
# Don't add in ascending or descending order
self.non_empty = Stack()
self.non_empty.push(5)
self.non_empty.push(2)
self.non_empty.push(7)
self.non_empty.push(2)
def test_length(self):
self.assertEqual(len(self.new), 0)
self.assertEqual(len(self.empty), 0)
self.assertEqual(len(self.non_empty), 4)
def test_is_empty(self):
self.assertTrue(self.new.is_empty())
self.assertTrue(self.empty.is_empty())
self.assertFalse(self.non_empty.is_empty())
def test_lifo_order(self):
self.assertEqual(self.non_empty.pop(), 2)
self.assertEqual(self.non_empty.pop(), 7)
self.assertEqual(self.non_empty.pop(), 2)
self.assertEqual(self.non_empty.pop(), 5)
def test_access_to_empty(self):
with self.assertRaises(AssertionError):
self.new.top()
with self.assertRaises(AssertionError):
self.empty.top()
with self.assertRaises(AssertionError):
self.new.pop()
with self.assertRaises(AssertionError):
self.empty.pop()
def test_membership(self):
self.assertFalse(2 in self.new)
self.assertFalse(2 in self.empty)
self.assertTrue(2 in self.non_empty)
self.assertTrue(5 in self.non_empty)
self.assertTrue(7 in self.non_empty)
