org.apache.xpath.functions
Class Function

java.lang.Object
  |
  +--org.apache.xpath.Expression
        |
        +--org.apache.xpath.functions.Function

Direct Known Subclasses:

FuncCurrent, FuncExtFunction, FuncFalse, FuncLast, FuncPosition, FunctionOneArg, FuncTrue

public class Function

extends Expression

**For advanced use only** This is a superclass of all XPath functions. This allows two ways for the class to be called. One method is that the super class processes the arguments and hands the results to the derived class, the other method is that the derived class may process it's own arguments, which is faster since the arguments don't have to be added to an array, but causes a larger code footprint.

See Also:

Serialized Form

Constructor Summary

Function()

Method Summary

void	checkNumberArgs(int argNum) Check that the number of arguments passed to this function is correct.
XObject	execute(XPathContext xctxt) Execute an XPath function object.
void	setArg(Expression arg, int argNum) Set an argument expression for a function.

Methods inherited from class org.apache.xpath.Expression

assert, canTraverseOutsideSubtree, error, setSourceLocator, warn

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Function

public Function()

Method Detail

setArg

public void setArg(Expression arg,
                   int argNum)
            throws WrongNumberArgsException

Set an argument expression for a function. This method is called by the XPath compiler.

Parameters:

arg - non-null expression that represents the argument.

argNum - The argument number index.

Throws:

WrongNumberArgsException - If the argNum parameter is beyond what is specified for this function.

checkNumberArgs

public void checkNumberArgs(int argNum)
                     throws WrongNumberArgsException

Check that the number of arguments passed to this function is correct. This method is meant to be overloaded by derived classes, to check for the number of arguments for a specific function type. This method is called by the compiler for static number of arguments checking.

Parameters:

argNum - The number of arguments that is being passed to the function.

Throws:

WrongNumberArgsException -

execute

public XObject execute(XPathContext xctxt)
                throws TransformerException

Execute an XPath function object. The function must return a valid object.

Parameters:

xctxt - The execution current context.

Returns:

A valid XObject.

Throws:

TransformerException -

Overrides:

execute in class Expression