/// <summary>
/// add an entry at a specified position
/// </summary>
/// <param name="index">the position</param>
/// <param name="o">the entry to add</param>
public void Add(int index, Object o)
{
Node newNode = new Node();
Node probe;
newNode.dataItem = o;
if (head == null)
{
newNode.nextNode = null;
head = newNode;
}
else
{
if (index == 0)
{
newNode.nextNode = head;
head = newNode;
}
else
{
probe = head;
int i = 0;
while ((i < index - 1) && (probe.nextNode != null))
{
probe = probe.nextNode;
i++;
}
newNode.nextNode = probe.nextNode;
probe.nextNode = newNode;
}
}
}
/// <summary>
/// dequeues the item at the head of the queue
/// </summary>
/// <returns>the item dequeued</returns>
public Object Dequeue()
{
if (head == null)
return null;
else
{
Node temp = new Node();
temp = head;
head = head.nextNode;
if (head == null) tail = null;
return temp.dataItem;
}
}
/// <summary>
/// sets all queue entries to null
/// </summary>
public void Destroy()
{
Node temp = new Node();
Node setNull = new Node();
temp = head;
while (temp != null)
{
setNull = temp;
temp = temp.nextNode;
setNull = null;
}
head = null;
tail = null;
}
/// <summary>
/// enqueues an item
/// </summary>
/// <param name="o">the item to enqueue</param>
public void Enqueue(Object o)
{
Node newNode = new Node();
newNode.dataItem = o;
if (tail == null)
{
head = newNode;
tail = newNode;
}
else
{
tail.nextNode = newNode;
tail = newNode;
}
}
/// <summary>
/// default constructor
/// </summary>
public SimpleQueue()
{
// initialise head and tail references
head = null;
tail = null;
}
/// <summary>
/// default constructor
/// </summary>
public SimpleLinkedList()
{
// initialise head reference
head = null;
}
/// <summary>
/// sets the entry at the specified position
/// </summary>
/// <param name="index">the position</param>
/// <param name="o">the entry previously at that position</param>
/// <returns></returns>
public Object Set(int index, Object o)
{
Node probe;
Node oldNode = new Node();
if (head == null)
return null;
else
{
if (index == 0)
{
oldNode.dataItem = head.dataItem;
head.dataItem = o;
return oldNode.dataItem;
}
else
{
probe = head;
int i = 0;
while ((i < index - 1) && (probe.nextNode != null))
{
probe = probe.nextNode;
i++;
}
if (probe.nextNode != null)
{
oldNode.dataItem = probe.nextNode.dataItem;
probe.nextNode.dataItem = o;
return oldNode.dataItem;
}
else
return null;
}
}
}
/// <summary>
/// removes the first entry which matches the target object
/// </summary>
/// <param name="o">the target object</param>
/// <returns></returns>
public bool Remove(Object o)
{
Node probe = new Node();
Node previous = new Node();
if (head == null)
return false;
else
{
if (head.dataItem.Equals(o))
{
head = head.nextNode;
return true;
}
else
{
probe = head;
previous = head;
while (!probe.dataItem.Equals(o) && probe.nextNode != null)
{
previous = probe;
probe = probe.nextNode;
}
if (probe.dataItem.Equals(o))
{
previous.nextNode = probe.nextNode;
probe = null;
return true;
}
else
return false;
}
}
}
