package BoxTools;
/**
*	A <code>List</code> object maintains a linked list of elements of type <code>T</code>.
*	Each element is contained in a <code>Link</code> object, and these <code>Link</code>
*	objects are linked together. A <code>List</code> object has a pointer to these linked
*	<code>Link</code> objects, which  are linked in one way.
*	A <code>List</code> object must be declared local, but the elements in it can be global.
*	<code>List</code> is implemented like a stack. The first element added to it appears at
*	the end of the list.
*	<p>Usage: A <code>List</code> object must be declared local.
*	@see Link
*	@version 1.1
*	@author Tong Wen, LBNL
*	@since 1.0
*/
template<class T> public class List{
	/** the starting <code>Link</code> object, which contains the last element. */
	protected template Link<T> local firstLink;	
	/** the current <code>Link</code> object  in the list. */
	protected template Link<T> local currentLink;
	/** the number of elements contained  in the list. */
	protected  int size=0;

	public inline List(){
		firstLink=null;
		currentLink=firstLink;
	}
	public final inline local void clear(){
		firstLink=null;
		currentLink=firstLink;
		size=0;
	}
	public final inline local void addElement(T newElement){
		firstLink=new template Link<T>(firstLink,newElement);
		currentLink=firstLink;
		size++;
	}
	public final inline local void advance(){
		if (currentLink!=null) currentLink=currentLink.nextLink;		
	}
	
	public final inline local T access(){return currentLink.element;}
	/** If <code>curruentlink==null</code>, using this method will cause a runtime exception. */
	public final inline local void setElement(T element){currentLink.element=element;}
	public final inline local boolean endp(){return (currentLink==null);}
	public final inline local void reset(){currentLink=firstLink;} 
	/** Returns the element at position <code>index</code>. 
	 *  If  <code>index</code> is out of range, the last element is returned.
	 */
	public final local T elementAt(int index){
		if (index>=size) {
			Util.printErrMsg("List::elementAt( ): the index is out of range! The last element will be returned.");	
			index=size;
		    }
		int steps=size-index-1;
		reset();
		for (int i=0;i<steps;i++) advance();
		return access();
	} 
 	/** Sets the element at position <code>index</code>. 
	 *  If  <code>index</code> is out of range, the last element is set.
	 */
	public final local void setElementAt(T newElement, int index){
		if (index>=size) {
			Util.printErrMsg("List::elementAt( ): the index is out of range!");	
			return;
		    }
		else{
			int steps=size-index-1;
			reset();
			for (int i=0;i<steps;i++) advance();
			currentLink.element=newElement;
		}
	} 
	/**Shallow copy of this <code>List</code> object. */
	public final  local template List<T> local copy(){
		template List<T> local newList=new template List<T>();
		reset();
		if (size>0){
			newList.firstLink=new template Link<T>(null,access());
			newList.currentLink=newList.firstLink;
			template Link<T> local tempLink;
			newList.size++;
			for (int i=1;i<size;i++){
				tempLink=new template Link<T>();
				newList.currentLink.setNextLink(tempLink);
				advance();
				tempLink.setElement(access());
				newList.advance();
				newList.size++;
			}
		}
		return newList;
	}

	public final inline local int size(){return this.size;}
	public final inline local boolean isEmpty(){return (size==0);}
	public final local T [] local toArray(){
		T [] local array=new T [size];
		for (int i=0;i<size;i++) array[i]=elementAt(i);
		return array;
	}
	public final local T [1d] local toTiArray(){
		T [1d] local array=new T [[0:size-1]];
		for (int i=0;i<size;i++) array[i]=elementAt(i);
		return array;
	}
}