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javax.xml.xpath

public Interface XPathFunctionResolver

Imports
javax.xml.namespace.QName

XPathFunctionResolver provides access to the set of user defined XPathFunctions.

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.

Authors
Norman Walsh, Jeff Suttor
Since
1.5
See Also
XML Path Language (XPath) Version 1.0, Core Function Library

Method Summary

Modifier and TypeMethod and Description
public XPathFunction

Returns:

The function or null if no function named functionName with arity arguments exists.
resolveFunction
(QName
The function name.
functionName
,
int
The number of arguments that the returned function must accept.
arity
)

Find a function in the set of available functions.

Method Detail

resolveFunctionback to summary
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.

Parameters
functionName:QName

The function name.

arity:int

The number of arguments that the returned function must accept.

Returns:XPathFunction

The function or null if no function named functionName with arity arguments exists.

Exceptions
NullPointerException:
If functionName or arity is null.