/* Class IntRevolver is a cyclic data structure
 * where each cell holds an integer number.
 * The individual elements of this 'revolver'  
 * contain the integer number and a pointer to 
 * the next cell.
 *
 * For simplicity we access the cells of the 
 * list elements directly (data being the integer 
 * number, next being the pointer to the next
 * list element) instead of using methods.
 *
 * Carsten Butz, November 2002
 */
class IntRevolver{

  private IntListElement current = null;

  int getCurrent(){
    if(current == null)
      return 0;
    else
      return current.data;
  }

  void insert(int d){
    IntListElement nile = new IntListElement(d);

    if(current == null){
      /* revolver must be empty */
      current = nile;
      current.next = current;
    }
    else{
      /* revolver contains at least one element */
      nile.next = current.next;
      current.next = nile;
    }
    return;
  }

  IntListElement remove(){
    /* returnElement contains the pointer that will be returned */
    IntListElement returnElement = null;

    if(current != null){
      /* revolver contains at least one element */
      returnElement = current.next;
      
      if(current.next == current){
	/* revolver contains exactly one element */
	current = null;
      }
      else{
	/* revolver contains more than one element */
	current.next = returnElement.next;
      }
    }
    return returnElement; 
  }

  void next(){
    current = current.next;
    return;
  }

  int count(){
    int howMany = 0;

    if(current != null){
      /* There is at least one element.
       * Use start as a marker, use current
       * to run through all cells until you
       * are back to start.
       */
      IntListElement start = current;
      do{
	current = current.next;
	howMany++;
      }while(start != current);
      
    }
    return howMany;
  }

  IntListElement find(int key){
    IntListElement r = null;
    boolean found = false;

    IntListElement start = current;
    do{
      if(key == current.data){
	r = current;
	found = true;
      }
      current = current.next;
    }while(start != current && !found);

    return r;
  }

  public String toString(){
    String s = "";
 
    if(current!=null){
      IntListElement start = current;
      
      do{
	s = s + current.data + "\n";
	/* Use the following line if you want to
	 * see the contents of your revolver printed 
	 * on one line.
	 */
	//s = s + current.data +"\t";
	current = current.next;
      }while(start != current);
    }
    return s;
  }

}