class Queue:
def __init__(self):
self._linked_list = LinkedList()
def enqueue(self, item):
self._linked_list.add_tail(Node(item))
def dequeue(self):
if (self._linked_list.is_empty()):
raise IndexError("Dequeue from empty queue")
else:
value = self._linked_list._head.value
self._linked_list.remove_head()
return value
def peek(self):
if (self._linked_list.is_empty()):
raise IndexError("Peek from empty queue")
else:
return self._linked_list._head.value
class TestLinkedList(unittest.TestCase):
def setUp(self):
self._linked_list = LinkedList()
def test_is_empty(self):
assert(self._linked_list.is_empty())
self._linked_list.add_head(Node(1))
self.assertFalse(self._linked_list.is_empty())
def test_empty_linked_list(self):
empty = self._linked_list.linked_list_as_string()
assert(self._linked_list._counter == 0)
assert(empty == "HEAD -> TAIL")
def test_add_node_to_head(self):
self._linked_list.add_head(Node(1))
assert(self._linked_list._counter == 1)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 1 -> TAIL")
def test_add_two_nodes_to_head(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
assert(self._linked_list._counter == 2)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> 1 -> TAIL")
def test_add_node_to_tail_of_empty_list(self):
self._linked_list.add_head(Node(1))
assert(self._linked_list._counter == 1)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 1 -> TAIL")
def test_add_node_to_tail_of_list_with_items(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
assert(self._linked_list._counter == 2)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> 1 -> TAIL")
self._linked_list.add_tail(Node(0))
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> 1 -> 0 -> TAIL")
def test_add_multiple_tails(self):
self._linked_list.add_tail(Node(1))
self._linked_list.add_tail(Node(2))
self._linked_list.add_tail(Node(3))
self._linked_list.add_tail(Node(4))
assert(self._linked_list._counter == 4)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 1 -> 2 -> 3 -> 4 -> TAIL")
def test_remove_tail_from_linked_list_with_one_item(self):
self._linked_list.add_head(Node(1))
assert(self._linked_list._counter == 1)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 1 -> TAIL")
self._linked_list.remove_tail()
assert(self._linked_list._counter == 0)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> TAIL")
def test_remove_tail_from_linked_list_with_two_items(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
assert(self._linked_list._counter == 2)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> 1 -> TAIL")
self._linked_list.remove_tail()
assert(self._linked_list._counter == 1)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> TAIL")
def test_remove_tail_from_linked_list_with_three_items(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
self._linked_list.add_head(Node(3))
assert(self._linked_list._counter == 3)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 3 -> 2 -> 1 -> TAIL")
self._linked_list.remove_tail()
assert(self._linked_list._counter == 2)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 3 -> 2 -> TAIL")
def test_remove_head_from_linked_list_with_one_item(self):
self._linked_list.add_head(Node(1))
assert(self._linked_list._counter == 1)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 1 -> TAIL")
self._linked_list.remove_head()
assert(self._linked_list._counter == 0)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> TAIL")
def test_remove_head_from_linked_list_with_two_items(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
assert(self._linked_list._counter == 2)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> 1 -> TAIL")
self._linked_list.remove_head()
assert(self._linked_list._counter == 1)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 1 -> TAIL")
def test_remove_head_from_linked_list_with_three_items(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
self._linked_list.add_head(Node(3))
assert(self._linked_list._counter == 3)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 3 -> 2 -> 1 -> TAIL")
self._linked_list.remove_head()
assert(self._linked_list._counter == 2)
s = self._linked_list.linked_list_as_string()
assert(s == "HEAD -> 2 -> 1 -> TAIL")
def test_get_enumerator(self):
self._linked_list.add_head(Node(1))
self._linked_list.add_head(Node(2))
self._linked_list.add_head(Node(3))
assert(self._linked_list._counter == 3)
enumerator = self._linked_list.enumerator()
next = enumerator.get_next()
assert(next.value == 3)
next = enumerator.get_next()
assert(next.value == 2)
next = enumerator.get_next()
assert(next.value == 1)