import java.util.*;

public aspect FailSafeEnumThread {

    pointcut vector_update() :
	call(* Vector.add*(..)) ||
	call(* Vector.clear()) ||
        call(* Vector.insertElementAt(..)) ||
        call(* Vector.remove*(..)) ||
        call(* Vector.retainAll(..)) ||
        call(* Vector.set*(..));

     tracematch(Vector ds, Enumeration e) {
	sym create_enum after returning(e) :
        (call(* Vector+.elements()) && target(ds)) ||
        (call(Enumeration+.new(..)) && args(ds));
	sym call_next before : call(Object Enumeration.nextElement())
	    && target(e);
        sym update_source after : vector_update() 
            && target(ds);

	create_enum call_next* update_source+ call_next
	{
	}
    }
          

	public static void main(String[] args) {
		//safe
		c1.add("");     
		//safe but not recognized because enumerations are collapsed
		Enumeration e = c1.elements();
		e.nextElement();
		
		thread();		//this thread may modify c1 any time 
		foo();			//this method iterates over c1; this may cause an exception when
						//interleaved badly with the thread
	}
	
	static final Vector c1 = new Vector();
	static final Vector c2 = new Vector();

	static void foo() {		
		Enumeration e = c1.elements();
		e.nextElement();
	}
	
	static void thread() {
		new Thread() {
			
			public void run() {
				c1.add("");//this has to stay
				
				Vector v = new Vector();
				Enumeration en = v.elements();
				en.nextElement();
				v.add("");
			}
			
		}.start();
	}

	
	
}