/*
 * IntSet.java
 *
 */

package datastructures;
import java.util.Vector;
/**
 *
 * @author  hs
 */
public class IntSet1 implements IntSet {
     private Vector impSet;
    
    // vector representation of int sets
    // abstr (o) = {c.impSet[i].intValue | 0<=i<c.impSet.size()}
    //              where o is an object of Type IntSet1
    // inv: o.impSet != null &&
    //      for all int i: o.impSet.getIndex(i) instanceof Integer 
    
      
    /** Creates a new instance of IntSet */
    public IntSet1() {
    impSet = new Vector();
    }
   
    
    public void add(int e) {
       impSet.add(new Integer(e)); 
    }
     
    public boolean isEmpty() {
    return impSet.size()==0;
    }
    
    public int size() { 
     int size = 0; 
     if (impSet.size()==0) return 0;
        for (int i = 0; i < impSet.size(); i++){
            Integer e = (Integer)impSet.elementAt(i);
            if (impSet.indexOf(e) == i )   // first occurence
               size++;
        }
     return size; 
    }
    
    public boolean contains(int e) {
      return impSet.indexOf(new Integer(e))>=0;    // indexOf(elem) = first index of elem in vector, 
                                               //   is not existent: return -1
    }    
    
    public boolean remove(int e) {
     Integer oe = new Integer(e);
     boolean isContained = impSet.remove(oe);
     boolean b=isContained; 
     while (b)
         b = impSet.remove(oe);  
     return isContained;
     }
    
    public void showSet(){
        //effect: prints elements of the set
        if (impSet.size()==0) return;
        for (int i = 0; i < impSet.size(); i++){
            Integer e = (Integer)impSet.elementAt(i);
            if (impSet.indexOf(e) == i )   // first occurence
               System.out.print(e.intValue() + ", ");
         }
    }
                       
}