The Use of Metagrammars To Help Construct Reverse Engineering Tools For Existing Software Comprehension

Most of the maintenance costs incurred in software system maintenance concern system comprehension. This comprehension is used to perform such activities as testing, maintenance, reverse engineering, optimizing, re-engineering, etc., and can be regarded from two viewpoints. The first has a psychological perspective, and aims to identify and classify the documents the maintenance engineer would like to have (which must often be extracted from code) in order to facilitate their understanding. The second regards certain technical aspects, and deals with the way in which these documents will be extracted from code if they do not already exist. The present paper tackles the latter aspect. In particular, it will set out a methodology based on the concept of a ''metagrammar'', through which the extraction/abstraction process can be generalized, thus making it independent of the language in which the code to be analyzed is written. For this purpose, a tool, called RE_Tool, has been set up to implement this methodology. The tool has been built in the LPA Prolog language, and runs on an MS Windows 3.1 platform on a 386/486 Personal Computer.