class Queue(object):
"""Create a queue data structure"""
def __init__(self):
self.container = DoubleLinkedList()
def enqueue(self, val):
"""Inserts value to queue"""
self.container.insert(val)
def dequeue(self):
"""Removes next item and returns it"""
return self.container.shift()
def peek(self):
"""Return next value in queue without dequeuing it"""
if self.container.tail_node is None:
return None
return self.container.tail_node.value
def size(self):
"""Return size of queue, 0 if empty"""
if self.container.head_node is None:
return 0
cursor = self.container.head_node
if self.container.head_node.next == self.container.tail_sentinal:
return 1
size = 1
while cursor.next != self.container.tail_sentinal:
size += 1
cursor = cursor.next
return size
def test_remove_value_not_in_list():
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.append(5)
dll.insert(10)
dll.append(15)
dll.insert(20)
with pytest.raises(ValueError):
dll.remove('bananas')
def test_pop():
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.append(5)
dll.insert(10)
dll.append(15)
dll.insert(20)
return_value_1 = dll.pop()
assert return_value_1 == 20
assert dll.head_node.value == 10
def test_remove_tail():
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.insert(3)
dll.insert(2)
dll.insert(1)
assert dll.tail_node.value == 3
dll.remove(3)
assert dll.tail_node.value == 2
assert dll.tail_node.next == dll.tail_sentinal
def test_remove_value():
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.insert(3)
dll.insert(2)
dll.insert(1)
dll.remove(2)
assert dll.head_node.next.value == 3
assert dll.tail_node.value == 3
assert dll.tail_node.previous == dll.head_node
def test_shift():
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.append(5)
dll.insert(10)
dll.append(15)
dll.insert(20)
# [20, 10, 5, 15]
return_value_1 = dll.shift()
assert return_value_1 == 15
assert dll.tail_node.value == 5
def test_insert():
# test multiple insert calls
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.insert(5)
dll.insert(10)
assert dll.head_node.value == 10
assert dll.head_node.next.value == 5
assert dll.head_node.previous == dll.head_sentinal
assert dll.tail_node.value == 5
assert dll.tail_node.next == dll.tail_sentinal
assert dll.tail_node.previous == dll.head_node
def test_insert_on_empty_list():
# test insert single element to empty list
from double_linked_list import DoubleLinkedList
dll = DoubleLinkedList()
dll.insert(5)
assert dll.head_node.value == 5
assert dll.head_node.next == dll.tail_sentinal
assert dll.head_node.previous == dll.head_sentinal
# list is 1 element long, so head and tail are that element
assert dll.tail_node.value == 5
assert dll.tail_node.next == dll.tail_sentinal
assert dll.tail_node.previous == dll.head_sentinal
class TestDoubleLinkedList(unittest.TestCase):
def setUp(self):
self.double_list = DoubleLinkedList()
def test_insert_one_item(self):
self.assertEqual(0, self.double_list.size)
self.assertEqual(None, self.double_list.root)
item1 = create_item(1, 1)
self.double_list.insert(item1)
self.assertEqual(1, self.double_list.size)
self.assertEqual(item1, self.double_list.root)
self.assertEqual(None, self.double_list.root.next)
self.assertEqual(None, self.double_list.root.before)
def test_insert_two_items(self):
self.assertEqual(0, self.double_list.size)
self.assertEqual(None, self.double_list.root)
item1 = create_item(1, 1)
item2 = create_item(2, 2)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.assertEqual(2, self.double_list.size)
self.assertEqual(item1, self.double_list.root)
self.assertEqual(item2, self.double_list.root.next)
self.assertEqual(None, self.double_list.root.next.next)
self.assertEqual(item1, self.double_list.root.next.before)
def test_insert_three_items(self):
self.assertEqual(0, self.double_list.size)
self.assertEqual(None, self.double_list.root)
item1 = create_item(1, 1)
item2 = create_item(2, 2)
item3 = create_item(3, 3)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.double_list.insert(item3)
self.assertEqual(3, self.double_list.size)
self.assertEqual(item1, self.double_list.root)
self.assertEqual(item2, self.double_list.root.next)
self.assertEqual(item1, self.double_list.root.next.before)
self.assertEqual(item3, self.double_list.root.next.next)
self.assertEqual(item2, self.double_list.root.next.next.before)
self.assertEqual(item1, self.double_list.root.next.next.before.before)
def test_search_item_exist(self):
item1 = create_item(1, 1)
item2 = create_item(2, 2)
item3 = create_item(3, 3)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.double_list.insert(item3)
self.assertEqual(item3, self.double_list.search(item3.id_))
def test_search_item_not_exist(self):
item1 = create_item(1, 1)
item2 = create_item(2, 2)
item3 = create_item(3, 3)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.double_list.insert(item3)
self.assertEqual(None, self.double_list.search(4))
def test_search_in_list_empty(self):
self.assertEqual(None, self.double_list.search(1))
def test_remove_last_item(self):
item1 = create_item(1, 1)
item2 = create_item(2, 2)
item3 = create_item(3, 3)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.double_list.insert(item3)
item_removed = self.double_list.delete(item3.id_)
self.assertEqual(item3, item_removed)
self.assertEqual(2, self.double_list.size)
self.assertEqual(item1, self.double_list.root)
self.assertEqual(item2, self.double_list.root.next)
def test_remove_first_item(self):
item1 = create_item(1, 1)
item2 = create_item(2, 2)
item3 = create_item(3, 3)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.double_list.insert(item3)
item_removed = self.double_list.delete(item1.id_)
self.assertEqual(item1, item_removed)
self.assertEqual(2, self.double_list.size)
self.assertEqual(item2, self.double_list.root)
self.assertEqual(item3, self.double_list.root.next)
def test_remove_middle_item(self):
item1 = create_item(1, 1)
item2 = create_item(2, 2)
item3 = create_item(3, 3)
self.double_list.insert(item1)
self.double_list.insert(item2)
self.double_list.insert(item3)
item_removed = self.double_list.delete(item2.id_)
self.assertEqual(item2, item_removed)
self.assertEqual(2, self.double_list.size)
self.assertEqual(item1, self.double_list.root)
self.assertEqual(item3, self.double_list.root.next)