org.apache.xpath.functions

Class Function

public abstract class Function extends Expression

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.

UNKNOWN: advanced

Method Summary
voidcallArgVisitors(XPathVisitor visitor)
Call the visitors for the function arguments.
voidcallVisitors(ExpressionOwner owner, XPathVisitor visitor)
voidcheckNumberArgs(int argNum)
Check that the number of arguments passed to this function is correct.
booleandeepEquals(Expression expr)
XObjectexecute(XPathContext xctxt)
Execute an XPath function object.
voidpostCompileStep(Compiler compiler)
This function is currently only being used by Position() and Last().
voidsetArg(Expression arg, int argNum)
Set an argument expression for a function.

Method Detail

callArgVisitors

public void callArgVisitors(XPathVisitor visitor)
Call the visitors for the function arguments.

callVisitors

public void callVisitors(ExpressionOwner owner, XPathVisitor visitor)

See Also: XPathVisitable

checkNumberArgs

public void checkNumberArgs(int argNum)
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

deepEquals

public boolean deepEquals(Expression expr)

See Also: deepEquals

execute

public XObject execute(XPathContext xctxt)
Execute an XPath function object. The function must return a valid object.

Parameters: xctxt The execution current context.

Returns: A valid XObject.

Throws: javax.xml.transform.TransformerException

postCompileStep

public void postCompileStep(Compiler compiler)
This function is currently only being used by Position() and Last(). See respective functions for more detail.

setArg

public void setArg(Expression arg, int argNum)
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.

Copyright © 2005 Apache XML Project. All Rights Reserved.