class StackLinkedList:
"""
This is a Linked List based implementation of a stack
"""
# Creates an empty list with Linked List
def __init__(self):
self._items = SinglyLinkedList()
# Returns True if stack is Empty otherwise returns False
def isEmpty(self):
return self._items.node_counter == 0
def __len__(self):
return self._items.node_counter
# Returns the top item of the stack without removing it
def peek(self):
assert not self.isEmpty(), "Cannot peek at an empty stack"
return self._items.get_head()
# Remove and return the last item of the stack
def pop(self):
assert not self.isEmpty(), "Cannot pop from an empty stack"
last_item = self.peek()
self._items.delete_start()
return last_item
# Push an item at the top of the stack
def push(self, item):
self._items.insert_start(item)
