#include <DbXml.hpp>

class DbXml::XmlExternalFunction {
public:
	virtual XmlResults execute(XmlTransaction &txn, XmlManager &mgr, const XmlArguments &args) const;
	virtual void close();
};

The XmlExternalFunction class is used to implement XQuery extension functions in C++. An implementor creates a subclass of XmlExternalFunction and returns an instance of the class from XmlResolver::resolveExternalFunction. Returned instances may be singleton objects which means the application must eventually free the memory, or new instances in which case the instance should delete itself in its XmlExternalFunction::close method.

This method is called from within a query to execute the function for which the instance was implemented. It returns an XmlResults object used by the query for further processing.

• The XmlTransaction in which the operation is running.

• The XmlManager instance controlling the operation.

• The XmlArguments object that can be used to retrieve the function arguments.

This method is called when the query has finished using the object. It allows the implementation to clean up if necessary. If a new instance of XmlExternalFunction is returned from XmlResolver::resolveExternalFunction then this method will probably need to delete itself to avoid memory leaks.