for (int i = 0; i < node.jjtGetNumChildren(); i++) {
if (node.jjtGetChild(i) instanceof ASTVar) {
final ASTVar var = (ASTVar) node.jjtGetChild(i);
try {
operator.addProjectionElement(var.toQueryString());
} catch (final ModificationException e) {
e.printStackTrace();
}
} else if (node.jjtGetChild(i) instanceof ASTQuotedURIRef) {
final ASTQuotedURIRef var = (ASTQuotedURIRef) node