queue.py

'''
   Queue
   The queue is, one can say, the inverse of the stack. It is only possible to pop the first element rather than the last.
   The queue is very easily conceptualized, it is just to close one's eyes and imagine oneself in a queue outside the
   best carusel or attraction of one's child hood. The queue works exactly like a regular queue that is you push a value
   and that value that is pushed to the queue kindly awaits its turn to enter. This is implemented using a linked list as
   a linked list can easily remove the first element in constant time O(1) you only need a pointer for that. A generalized
   graph traversal using a queue will amount to a BFS.
'''

import linked_list
class queue:
    def __init__(self):
        self.linkedList = linked_list.linked_list()
        self.size = 0

    def __len__(self):
        return self.size

    def push(self, element):
        self.linkedList.insertion(element)
        self.size += 1

    def pop(self):
        try:
            pop_element = self.linkedList.remove_first()
            self.size -= 1

            return pop_element
        except:
            print("You cannot pop from an empty queue!")

    def peek(self):
        return self.linkedList.top_node.value

    def element_wise_print(self):
        self.linkedList.element_wise_print()