class Deque(object):
"""This is the Deque data structure.
Methods:
append(): Append a Node with given value to the tail.
appendleft(): Push a Node with given value to the head.
pop(): Remove the node from the head, return the value.
popleft(): Remove the node from the tail, return the value.
peek(): Return the value from the tail node.
peekleft(): Return the value from the head node.
"""
def __init__(self, maybe_an_iterable=None):
"""Initialize a deque data structure."""
self._container = DblLinkedList(maybe_an_iterable)
def append(self, val):
"""Append a node with given value to the tail."""
self._container.append(val)
def appendleft(self, val):
"""Append a node with given value to the head."""
self._container.push(val)
def pop(self):
"""Remove the node from the tail and return the value."""
try:
return self._container.shift()
except IndexError:
raise IndexError("Cannot pop from empty Deque.")
def popleft(self):
"""Remove the node from the head and return the value."""
try:
return self._container.pop()
except IndexError:
raise IndexError("Cannot popleft from empty Deque.")
def peek(self):
"""Give the value for the tail node."""
try:
return self._container.tail.value
except AttributeError:
return None
def peekleft(self):
"""Give the value for the head node."""
try:
return self._container.head.value
except AttributeError:
return None
def size(self):
"""Return the length of the deque."""
return self._container._size
def __len__(self):
"""Call the size method."""
return self.size()
class Deque(object):
"""Establish class for deque. Methods composed from dbl_linked_list."""
def __init__(self, seq=None):
"""Initialize deque."""
self._deque = DblLinkedList(seq)
def append(self, val):
"""Append value to end of deque."""
self._deque.append(val)
def appendleft(self, val):
"""Append value to front of deque."""
self._deque.insert(val)
def pop(self):
"""Remove last item from deque and return its value."""
try:
return self._deque.shift()
except IndexError:
raise IndexError("Cannot pop from end of an empty deque.")
def popleft(self):
"""Remove first item from deque and return its value."""
try:
return self._deque.pop()
except IndexError:
raise IndexError("Cannot pop from head of an empty deque.")
def peek(self):
"""Return value of last item in deque."""
try:
return self._deque.tail.val
except AttributeError:
return None
def peekleft(self):
"""Return value of first item in deque."""
try:
return self._deque.head.val
except AttributeError:
return None
def size(self):
"""Calculate number of items in the deque and return it."""
cur_node = self._deque.head
counter = 0
while cur_node:
counter += 1
cur_node = cur_node.next_node
return counter
class Deque(object):
"""Establish class for deque. Methods composed from dbl_linked_list."""
def __init__(self, seq=None):
"""Initialize deque."""
self._deque = DblLinkedList(seq)
def append(self, val):
"""Append value to end of deque."""
self._deque.append(val)
def appendleft(self, val):
"""Append value to front of deque."""
self._deque.insert(val)
def pop(self):
"""Remove last item from deque and return its value."""
try:
return self._deque.shift()
except IndexError:
raise IndexError("Cannot pop from end of an empty deque.")
def popleft(self):
"""Remove first item from deque and return its value."""
try:
return self._deque.pop()
except IndexError:
raise IndexError("Cannot pop from head of an empty deque.")
def peek(self):
"""Return value of last item in deque."""
try:
return self._deque.tail.val
except AttributeError:
return None
def peekleft(self):
"""Return value of first item in deque."""
try:
return self._deque.head.val
except AttributeError:
return None
def size(self):
"""Calculate number of items in the deque and return it."""
cur_node = self._deque.head
counter = 0
while cur_node:
counter += 1
cur_node = cur_node.next_node
return counter
def test_shift(seq, shift_val, tail_val):
"""Test the shift method of DblLinkedList class."""
from dbl_linked_list import DblLinkedList
test_list = DblLinkedList(seq)
assert test_list.shift() == shift_val
assert test_list.tail.val == tail_val