An example of in-class work. Construction of a FIFO Queue using nodes in python.

FIFO Queue

""" Name : Michael Minogue
Course : CMPS 1500-01
Lab Section : Tuesday 11:00 am-12:00 pm
Assignment : hw9pr1
Date : 11/10/2014
"""
class Node:
    # data
    # next

    # constructor
    def __init__(self, data):
        self.data = data
        self.next = None

    def __str__(self):
        return str(self.data) 

class Queue:
    # constructor
    def __init__(self):
        self.front = None
        self.rear = None
        self.size = 0
    def __str__(self):
        # front is head (first) node of list

        current = self.front
        thelist = ''
        while(current!=None):
            thelist = thelist + str(current) + ' '
            current = current.next
        return thelist
    def enqueue(self,item):
        if self.front == None:  #Case if Queue is completely empty
            self.front = Node(item)
            self.size += 1
        elif self.rear == None:     #Checks if Queue has only 1 node
            self.front.next = Node(item)
            self.rear = self.front.next
            self.size += 1
        else:   #Normal case to append to rear
            self.rear.next = Node(item)
            self.rear = self.rear.next
            self.size += 1
    def dequeue(self):
        if self.size != 0:      #Checks if Queue has nodes to remove
            toreturn = self.front
            self.front = self.front.next
            self.size -= 1
            return toreturn
        else:           #Case if Queue is empty
            return None
    def isEmpty(self):
        if self.size == 0:
            return True
        else:
            return False