Homework 10

Linked Queue

The purpose of this assignment is to implement a Circular Doubly Linked Queue, which is built around a linked lists. The behavior of a queue is First In First Out with two main operations, enqueue and dequeue. This implementation of the queue will use a dummy head node, which will act as a reference to the front of the queue and the back of the queue. When the queue is instantiated, the dummy head node's next and prev will point to itself. The dummy head node will only be deallocated when the queue object goes out of scope. When the first element is enqueued, a new node is added to the back of the queue (head's prev). For the dequeuing operation, the element at the front of the queue is removed and the value returned. Your task is to write the LinkedQueue.h header file and LinkedQueue.cpp Implementation file. Node.h, Node.cpp, and main.cpp will be given to you. Details for the queue's operations are given below.

• LinkedQueue() - the default constructor will allocate memory for a dummy head node and set head's next and prev to itself.
• ~LinkedQueue() - the destructor will call clear(), deallocate head, set head to NULL, and set count to 0.
• void clear() - this function will traverse and deallocate each node within the queue. Set head to NULL and count to 0 Set head's next and prev to head, and count to 0.
• Node<T>* createNode(const T&) - this will dynamically allocate a new Node object, assign the passed parameter to set the new node's data, and set the new node's next and prev to itself. Return the new node
• bool isEmpty() const - this function will return true if head's next is pointing to head, false otherwise
• int getCount() const - this function will return the count of elements within the queue
• bool enqueue(const T&) - this function will create a new node and insert the passed element to the back of the queue (head's prev), set the new node's next to head and new node's prev to head's prev. Then set the last node's next to the new node, and head's prev to new node, increment count, and return true. If bad_alloc return false.
• T dequeue() - this function will remove the first element from the queue, deallocate the Node for the element, decrement count, and return the element if the queue is not empty. Otherwise return a type casted (T)0.
• void print() - this function will traverse and print the contents of the queue, if the queue is not empty