AMQIterator(AMQReader reader,
    BooleanExpression expression) 
{
        this.reader=reader;
        this.expression=expression;
}

 public boolean hasNext() 
{
        try {
            this.nextLocation = reader.getNextMessage(currentLocation);
            Message next = nextLocation != null ? nextLocation.getMessage()
                    : null;
            if (expression == null) {
                return next != null;
            } else {
                while (next != null) {
                    MessageEvaluationContext context = new MessageEvaluationContext();
                    context.setMessageReference((MessageReference) next);
                    if (expression.matches(context)) {
                        return true;
                    }
                    this.nextLocation = reader.getNextMessage(currentLocation);
                    next = nextLocation != null ? nextLocation.getMessage()
                            : null;
                }
                valid=false;
                return false;
            }
        } catch (Exception e) {
            throw new RuntimeException(
                    "Failed to get next message from reader ", e);
        }
}

 public Message next() 
{
        if (valid && (nextLocation != null || hasNext())) {
            this.currentLocation=nextLocation;
            return nextLocation.getMessage();
        }
        return null;
}

 public  void remove() 
{
        throw new IllegalStateException("Not supported");
}