Well I know that it means to get an attribute from the session and cast it explicitly to SearchContext ...I am more concerned about SearchContext.I got this code from my product,but I dont have the developers,who developed this code.
If you are using IDE like Eclipse, you can search where exactly lies the class SearchContext. You can find from which library jar it comes... It will also show you the source code if jar contains it. Also try to find all the references of this class which will give more idea.