code: private void updateMemberReferenceCount(Node node) {
  		switch (node.getNodeType()) {
  			case AND:
  			case IN:
  			case OR:
  				RuleExpression expr = node.cast();
  				updateMemberReferenceCount(expr.getLeft());
  				updateMemberReferenceCount(expr.getRight());
  				break;
  
  			case VARIABLE:
  				break;
  
  			case MEMBER:
  				Member member = node.cast();
  				member.incrReferenceCount();
  				break;
  		}
  	}
docs: /*
  update the member reference counts