Reporting services and custom library

Question

Greetings, In my Reporting Services report I've added reference to my custom library. It works fine. I can display the string which is returned from my custom library method as follows:

=ClassLibrary1.MyClass.Parse("harry potter")

Above code works fine - it should return SQL query based on passed parameters. My question is, how can I use this code in my DataSource. I'm trying to do something like this:

SELECT * FROM =ClassLibrary1.MyClass.Parse(@searchedPhrase)

But the above code does not work and the error is returned :"Incorrect syntax near ="