Addition of a new function

[shruti]

Hello,   i have to add a new function to the xalan's xpath list of functions. i am adding a function for searching a list of words . It would be an extension to the xalan's contains function ...   //book[contains(./,"hello")] //book[contains-words(./,"hello hi","any")] - this would search for words hello and hi and returns all the nodes which have either hello or hi in their text.   For this i had to add a class (FunctionContainsWords.java) in the org/apache/xpath/functions package and make an appropriate entry for this function in the function table and keywords class   Could their be any alternative approach possible by which i could add this function by not changing the existing code . But by just deriving my own classes from the existing ones..   Please suggest...   thanx Shruti.