def test_append_empty():
dll = Dll()
dll.append(500)
assert dll.head.prev is None
assert dll.head.next_node is None
assert dll.head.value == 500
assert dll.head is dll.tail
def test_append_two_nodes():
"""Test append function to add to tail."""
from dll import Dll
test_dll = Dll()
test_dll.append(9)
test_dll.append('goat')
assert test_dll.tail.data == 'goat'
def test_shift():
"""Test shift function.
Should remove last node and return value.
"""
from dll import Dll
test_dll = Dll()
test_dll.append(8)
assert test_dll.shift() == 8
def test_remove_head():
dll = Dll()
dll.append(500)
dll.append(600)
dll.append(700)
dll.remove(500)
assert dll.head.value == 600
assert dll.head.next_node is dll.tail
assert dll.head.prev is None
def test_append():
dll = Dll()
dll.append(500)
first_node = dll.tail
dll.append(600)
assert dll.tail.prev is first_node
assert dll.tail.next_node is None
assert dll.tail.value == 600
assert dll.head.next_node is dll.tail
class Deque(object):
"""Create deque class object."""
def __init__(self):
"""Initialize new deque class object with a front and back."""
self._dll = Dll()
self.head = self._dll.head
self.tail = self._dll.tail
self._length = self._dll._length
@property
def length(self):
"""Use dll length method to return size of the deque."""
return self._dll._length
def append(self, data):
"""Use dll append method to add node with data at tail."""
self._dll.append(data)
def append_left(self, data):
"""Use dll push method to add node with data at front(head)."""
self._dll.push(data)
def pop(self):
"""Use dll shift method to remove node at back(tail)."""
return self._dll.shift()
def pop_left(self):
"""Use dll pop method to remove node from front(head)."""
return self._dll.pop()
def peek(self):
"""Use dll peek method to view node at back(tail)."""
if self.length == 0:
return None
return self._dll.tail.data
def peek_left(self):
"""Use dll peek method to view node at front(head)."""
if self.length == 0:
return None
return self._dll.head.data
def size(self):
"""Function uses build-in len function to show length."""
return self.length
class Deque(object):
"""Create deque data structure."""
def __init__(self):
"""Initalize a Deque."""
self._que = Dll()
def append(self, val):
"""Add an item to the deque."""
self._que.push(val)
def appendleft(self, val):
"""Append value to the front of the deque."""
self._que.append(val)
def pop(self):
"""Pop value from end of the deque and returns it."""
return self._que.pop()
def popleft(self):
"""Pop value from front of the deque and return it."""
return self._que.shift()
def peek(self):
"""Return next value in deque without dequeueing it."""
if self._que.head is not None:
return self._que.head.value
return None
def peekleft(self):
"""Return value of popleft but leaves value in deque."""
if self._que.tail is not None:
return self._que.tail.value
return None
def size(self):
"""Get length of deque."""
return self._que.__len__()
def test_append():
"""Test append function to add to tail."""
from dll import Dll
test_dll = Dll()
test_dll.append(9)
assert test_dll.tail.data == 9
def test_remove_not_found():
dll = Dll()
dll.append(600)
dll.insert(700)
with pytest.raises(LookupError):
dll.remove(500)
def test_shift():
dll = Dll()
dll.append(500)
dll.append(600)
assert dll.shift() == 600
assert dll.tail.next_node is None
def test_pop():
dll = Dll()
dll.append(500)
dll.append(600)
assert dll.pop() == 500
assert dll.head.prev is None