Flexible visitor interface for AST walking...

ComparingNode.java

public class ComparingNode implements DataFilterNode {

    public <P, R> R accept(DataFilterVisitor<P, R> visitor, P param) {
        return visitor.visitComparingNode(this, param);
    }

}

DataFilterNode.java

public interface DataFilterNode {
    public <P, R> R accept(DataFilterVisitor<P, R> visitor, P param);
}

DataFilterVisitor.java

public interface DataFilterVisitor<P, R> {

    R visitUnionNode(UnionNode node, P param);

    R visitIntersectionNode(IntersectionNode node, P param);

    R visitComparingNode(ComparingNode comparingNode, P param);
    ......
}

Or pass a newly created 'param' every time you start a new child node's visit.