import java.util.Iterator;

/* An instance of this class is for iterating over the members of a 
** set of integers (specifically, an instance of SetIntRange).
**
** @author R. McCloskey
** @version December 2022
*/
public class SetIntRangeIterator implements Iterator<Integer> {

   /* The iterator produced by this private class is such that the
   ** set's elements are guaranteed to be returned (by successive calls
   ** to next()) in ascending order.
   */

   // instance variables
   // ------------------

   private int currentMember;
   private SetIntRange theSet;

   /* Establishes the given set (s) as the one whose members 
   ** are to be iterated over. 
   */
   public SetIntRangeIterator(SetIntRange s) {
      theSet = s;
      advance(theSet.floor());
   }


   /* Reports whether or not there are any more members of 'theSet' to
   ** be returned via calls to next().
   */
   public boolean hasNext() {
      return currentMember <= theSet.ceiling();
   }

   /* Returns the smallest-valued member of 'theSet' that has not yet
   ** been returned by next().
   ** pre: hasNext()
   */
   public Integer next() {
      int result = currentMember;
      advance(currentMember+1);
      return result;
   }

   /* The remove operation is not supported.
   */
   public void remove()  { 
      throw new UnsupportedOperationException();
   }

   // private method
   // --------------

   /* Finishes with 'currentMember' being equal to the smallest-valued
   ** member of 'theSet' that is not less than 'candidate'.  In the case
   ** that no such number exists, 'currentMember' is set to one more than
   ** theSet.ceiling().
   */
   private void advance(int candidate) {
      final int ceiling = theSet.ceiling();
      while (candidate <= ceiling  && !theSet.isMemberOf(candidate)) { 
         candidate++; 
      }
      currentMember = candidate;
      
   }

}