javax.xml.xpath
Interface XPathFunctionResolver
public interface XPathFunctionResolver
XPathFunctionResolver
provides access to the set of user defined
XPathFunction
s.
XPath functions are resolved by name and arity.
The resolver is not needed for XPath built-in functions and the resolver
cannot be used to override those functions.
In particular, the resolver is only called for functions in an another
namespace (functions with an explicit prefix). This means that you cannot
use the
XPathFunctionResolver
to implement specifications
like
XML-Signature Syntax
and Processing which extend the function library of XPath 1.0 in the
same namespace. This is a consequence of the design of the resolver.
If you wish to implement additional built-in functions, you will have to
extend the underlying implementation directly.
$Revision: 226183 $, $Date: 2005-04-08 12:39:14 +0200 (Fri, 08 Apr 2005) $
resolveFunction
public XPathFunction resolveFunction(QName functionName,
int arity)
Find a function in the set of available functions.
If
functionName
or
arity
is
null
, then a
NullPointerException
is thrown.
functionName
- The function name.arity
- The number of arguments that the returned function must accept.
- The function or
null
if no function named functionName
with arity
arguments exists.