/**
*  This is a class containing functios 
*  for the Elements in the list.
*
*
*       @author Christian Ohlsson, Karlstad university 1999
*       @version 1.0.0
*/
public class Element { 
  Element suc; 
 
/**
* This is just the constructor.
*/   
  public Element() { suc = null; } 

/**   
*  Returns the current Element in the list
*/
  public Element suc() { return suc; } 

/**
*  This function inserts a new Element
*  at the end of the List. 
*  It first checks out if the List is empty, 
*  i.e the first Element is null, and then
*  the first Element is this Element.
*  Otherwise, it inserts the new Element
*  at the end of the List. 
*/
  public void into(List theList) { 
    if (theList.first==null) 
      theList.first = theList.last = this; 
    else { 
      theList.last.suc = this; 
      theList.last = this; 
    } 
    suc = null; 
  } 
     
/**
*  This function inserts a new Element at
*  the beginning of the list. 
*  It first checks out if the List is empty, 
*  i.e the first Element is null, and then
*  the first Element is this Element.
*  Otherwise, the Element that were in the
*  beginning, now is in second place and
*  the new Element is in front of the List.
*/
  public void intoAsFirst(List theList) { 
    if (theList.first==null) { 
      theList.first = theList.last = this; 
      suc = null; 
    } 
    else { 
      suc = theList.first; 
      theList.first = this; 
    } 
  } 
    
/**
*  This function deletes an Element in
*  the List by traversing through the
*  List until it gets to the Element
*  that should be deleted. 
*/
  public void out(List theList) { 
    Element prev = null; 
    Element e = theList.first; 
    while (e!=null && e!=this) { 
      prev = e; 
      e = e.suc; 
    } 
    if (e!=null) { 
      if (theList.last==this) 
        theList.last = prev; 
      if (theList.first==this) 
	  theList.first = suc; 
      else 
        prev.suc = suc; 
      suc = null; 
    } 
  }
}