Class List

			
				
					
						
							
					
					
						
							 template    class  
							
								List<class Type>
							
							 
						
					
				
				
					
						 Programmer: Ryan Davis  
					
				
			
			 
			
				Description: 
			
			
				 Define a "plug & play" linked list class that provides
 all mechanisms needed to store random homogonous data.
 the list is doubly linked and can be walked backwards or
 forwards. It can also find, remove, etc...
 
			
			   
			
				Public Methods: 
			
			
				
					  
					
					 
					
						List 
					
					(); 
					

					  Creates a new list with no nodes (except exemplars).
 
					

					

					   
					

					virtual  
					
						~List 
					
					(); 
					

					  Deletes all nodes in the list.
 
					

					

					   
					

					virtual Boolean  
					
						isEmpty 
					
					(); 
					

					  Returns true if list has more than zero nodes.
 
					

					

					   
					

					virtual Boolean  
					
						append 
					
					(const Type & item); 
					

					  Adds new node containing item to end of list. Returns true if
 successful.
 
					

					

					   
					

					virtual Boolean  
					
						prepend 
					
					(const Type & item); 
					

					  Adds a new node containing item to the begining of the list.
 Returns true if successful.
 
					

					

					   
					

					virtual Boolean  
					
						remove 
					
					(); 
					

					  Removes the node referenced by current(). If current is null, does
 nothing, otherwise returns true and calls reset.
 
					

					

					   
					

					virtual Boolean  
					
						find 
					
					(const Type & item); 
					

					  Locates first node containing item in list. Returns true if item is
 found and points current to that node. If not successful, returns
 false and doesn't change the previous value of current.
 
					

					

					   
					

					virtual UInteger  
					
						size 
					
					(); 
					

					  Returns the number of nodes (- exemplars) in list.
 
					

					

					   
					

					virtual void  
					
						reset 
					
					(); 
					

					  Sets current to NULL, for use with walkForward() & walkBackward()
 
					

					

					   
					

					virtual Boolean  
					
						atEnd 
					
					(); 
					

					  Returns true if current is at the last node in the list or number of
 nodes in list is zero. Returns false otherwise.
 
					

					

					   
					

					virtual Boolean  
					
						atHead 
					
					(); 
					

					  Returns true if current is at the first node in the list or number
 of nodes in list is zero. Returns false otherwise.
 
					

					

					   
					

					virtual Type &  
					
						value 
					
					(); 
					

					  Returns a reference to the value referenced by current.
 Conditions: will bomb if no items in list. Proper usage should test
 isEmpty().
 
					

					

					   
					

					virtual Boolean  
					
						walkForward 
					
					(); 
					

					  eqv. of postfix operator ++
 Returns false if current = tail or if the list contains no nodes
 Otherwise, if current == NULL then sets current to head :. returns
 true ..Otherwise sets current to current's next :. returns true
 
					

					

					   
					

					virtual Boolean  
					
						walkBackward 
					
					(); 
					

					  eqv. of postfix operator --
 Returns false if current = head or if the list contains no nodes
 Otherwise, if current == NULL then sets current to tail :. returns
 true ..Otherwise sets current to current's prev :. returns true
 Data
 
					

					

					  
				
			
			  
			
				Protected Methods: 
			
			
				
					  
					
					void  
					
						head 
					
					(ListNode<Type> * newHead); 
					

					    
					

					

					   
					

					ListNode<Type> *  
					
						head 
					
					(); 
					

					    
					

					

					   
					

					void  
					
						tail 
					
					(ListNode<Type> * newTail); 
					

					    
					

					

					   
					

					ListNode<Type> *  
					
						tail 
					
					(); 
					

					    
					

					

					   
					

					void  
					
						current 
					
					(ListNode<Type> * newCurrent); 
					

					    
					

					

					   
					

					ListNode<Type> *  
					
						current 
					
					(); 
					

					    
					

					

					  
				
			
			
				Protected Members: