The unit returns the operation condition and a changes characteristic line. Implementation using JAVA is additional difficulty for beginners. But the object oriented approach helps for the people who just want to make small changes to original programs. Of course, there should be enough directive discussion about the sample source of the original JAVA applet source code on which the student is going to add their application. The problem evaluator works on the database level right now.
More work needs to be done to fully implement the capabilities mentioned above.
Parsing will be a key technique to implement the ideas of evaluator. The Waite Group, Inc 1996.