package tracematches;

import java.util.*;

public class HasNext {
	
	static aspect HashNextCheck{
		
	    tracematch(Iterator i) {
	    	sym hasNext before: call(* java.util.Iterator+.hasNext()) && target(i);
	    	sym next before: call(* java.util.Iterator+.next()) && target(i);

			next next
			{
				if(System.getProperty("TMTEST_ACTIVE")!=null) {
				     throw new RuntimeException("Should call 'boolean Iterator.hasNext()'");
				}
			}
		}

	}
	
	public static void main(String[] args) {
		
		//unsafe
		Collection c = new ArrayList();
		c.add("");
		c.add("");
		Iterator iterator = c.iterator();
		System.out.println("n1");
		iterator.next();
		iterator.hasNext();
		System.out.println("n2");
		iterator.next();
		System.out.println("n3");
		iterator.next();
		
		//safe but not detected as such (needs must-point-to info) 
		Collection c2 = new ArrayList();
		for (Iterator i2 = c2.iterator(); i2.hasNext();) {
			i2.next();			
		}
	}
			
}