def is_balanced(string):
stack = Stack("Brackets")
for ch in string:
if ch in ["(", "{", "["]:
stack.push(ch)
else:
if ch == ")" and not stack.empty() and stack.peek() == "(":
stack.pop()
if ch == "}" and not stack.empty() and stack.peek() == "{":
stack.pop()
if ch == "]" and not stack.empty() and stack.peek() == "[":
stack.pop()
return False if stack else True
def test_new_stack_is_empty(self):
"""
Create an empty Stack.
Test that its size is 0.
"""
stack = Stack()
self.assertTrue(stack.empty())
self.assertEqual(stack.size(), 0)
def test_push_element(self):
"""
Push an element in stack.
Test that its size is 1.
"""
stack = Stack()
stack.push(None)
self.assertFalse(stack.empty())
self.assertEqual(stack.size(), 1)
def test_new_stack_from_generator(self):
"""
Create a Stack from a generator.
Test that its size equals to the number provided in the generator.
"""
stack = Stack(range(10))
self.assertFalse(stack.empty())
self.assertEqual(stack.size(), 10)
self.assertEqual(stack.top(), 9)
def test_new_stack_from_list(self):
"""
Create a Stack from a list.
Check that the size of stack equals to the size of the list.
Check that the top element of stack equals to the latest element of the list.
"""
data_to_stack = (1, 3, 5, 7, 2, 4)
stack = Stack(data_to_stack)
self.assertFalse(stack.empty())
self.assertEqual(stack.size(), len(data_to_stack))
self.assertEqual(stack.top(), data_to_stack[-1])
def test_push_sequence_of_elements(self):
"""
Push a sequence of elements in stack.
Test that its size equals to the length of the given sequence.
Pop all elements from stack and check reversed order.
"""
stack = Stack()
elements = (1, 2, "string", None, 0, Stack())
map(stack.push, elements)
self.assertEqual(stack.size(), len(elements))
for index, element in enumerate(reversed(elements)):
top = stack.top()
self.assertEqual(top, element)
stack.pop()
number_pop_elements = index + 1
expected_current_stack_size = len(elements) - number_pop_elements
self.assertEqual(stack.size(), expected_current_stack_size)
self.assertTrue(stack.empty())
def test_stack_not_empty_after_push(self):
stack = Stack()
stack.push(0)
assert not stack.empty()
def test_initialized_stack_is_empty(self):
stack = Stack()
assert stack.empty()
