import org.aspectj.lang.*;
import org.aspectj.lang.reflect.*;

aspect BoundaryChecker {

   pointcut growPoint(DataStructure s): call(public void DataStructure.push(Object)) && target(s);

   pointcut shrinkPoint(DataStructure s): call(public Object DataStructure.pop()) && target(s);

   void around(DataStructure s) throws java.lang.ArrayIndexOutOfBoundsException : growPoint(s) {
       int pos, size;
       pos = s.pos;
       size = s.size;

       if (pos == size) 
	   throw(new ArrayIndexOutOfBoundsException());
       System.out.println("push");
       proceed(s);
   }

   Object around(DataStructure s) throws java.lang.ArrayIndexOutOfBoundsException : shrinkPoint(s) {
       int pos;
       pos = s.pos;

       if (pos < 0) 
	   throw(new ArrayIndexOutOfBoundsException());
       System.out.println("pop");
       return proceed(s);
   }


}