/// <summary>
/// Constructor
/// </summary>
public Stack()
{
//Set headPointer and tailPointer to null(No items in Stack)
headPointer = tailPointer = null;
}
/// <summary>
/// Return last item on the Stack and remove it
/// </summary>
/// <returns>String of last item added to Stack</returns>
public String Pop()
{
String result;
//Grab data from last node
result = Peek();
//Remove last Node
//Check if the stack has only one item
if (headPointer == tailPointer)
{
headPointer = tailPointer = null;
}
else
{
//Prepare to walk list to find previous Node
Node nodeWalker = headPointer;
while (nodeWalker.Next != tailPointer)
{
nodeWalker = nodeWalker.Next;
}
//Found previous Node
//Set Next to null as it is now the last Node
nodeWalker.Next = null;
//Set tailPointer to last item in list
tailPointer = nodeWalker;
}
return result;
}
/// <summary>
/// Push a new item onto the Stack
/// </summary>
/// <param name="newString">Item to push onto the Stack</param>
/// TODO Is a null string allowed or throw an exception?
public void Push(String newString)
{
///Create the new Node
Node newNode = new Node(newString);
//Add the new Node to the list
//Check if the list is empty
if (headPointer == null)
{
//Set headPointer and tailPointer to the new Node
headPointer = tailPointer = newNode;
}
else
{
//Get the last Node and point it's next to the new Node
tailPointer.Next = newNode;
//Point tailPointer to the new Node
tailPointer = newNode;
}
}