Lecture20code-queue.txt

/*
 *  File: myqueue.h
 *  ----------------
 *
 *  Created by Julie Zelenski on 2/27/08.
 *
 */
#ifndef _myqueue_h
#define _myqueue_h

#include "genlib.h"

template <typename ElemType>
class MyQueue
{
 public:
	MyQueue();
	~MyQueue();
	
	bool isEmpty();
	void enqueue(ElemType e);
	ElemType dequeue();
	
  private:
	struct cellT {
		ElemType val;
		cellT *next;
	};
	
	cellT *head, *tail;

};

#include "myqueue.cpp"

#endif

/*
 *  File: myqueue.cpp
 *  ------------------
 *
 *  Created by Julie Zelenski on 2/27/08.
 *
 */

#include "myqueue.h"

template <typename ElemType>
MyQueue<ElemType>::MyQueue()
{	
	head = tail = NULL;
}

template <typename ElemType>
MyQueue<ElemType>::~MyQueue()
{
	// delete all cells
}


template <typename ElemType>
bool MyQueue<ElemType>::isEmpty()
{	
	return (head == NULL);
}

template <typename ElemType>
ElemType MyQueue<ElemType>::dequeue()
{
	if (isEmpty()) Error("dequeue empty q");
	ElemType front = head->val;
	cellT *old = head;
	head = head->next;
	delete old;
	return front;
}


template <typename ElemType>
void MyQueue<ElemType>::enqueue(ElemType s)
{
	cellT *newCell = new cellT;
	newCell->val = s;
	newCell->next = NULL;
	if (isEmpty()) {
		head = tail = newCell;
	} else {
		tail->next = newCell;
		tail = newCell;
	}
}