public Object visit(ASTCompare compareNode, Object data)
throws VisitorException
{
boolean leftIsNull = compareNode.getLeftOperand() instanceof ASTNull;
boolean rightIsNull = compareNode.getRightOperand() instanceof ASTNull;
CompareOp operator = compareNode.getOperator().getValue();
if (leftIsNull && rightIsNull) {
switch (operator) {
case EQ:
logger.warn("Use of NULL values in SeRQL queries has been deprecated, use BOUND(...) instead");