// Compile the query, if one is specified.
if (xmlQuery == null) {
// No query. The SqlXmlUtil instance is still on the stack. Pop it
// to restore the initial state of the stack.
constructor.pop();
} else {
// Compile the query. This will consume the SqlXmlUtil instance
// and leave the stack in its initial state.
constructor.push(xmlQuery);
constructor.push(xmlOpName);