A Taxonomy of Code Changes Occurring within a Statement or a Signature

Abstract

We propose a taxonomy of code changes at a granularity finer than the statement level. It classifies changes that occur within a statement or signature. We firstly define the changes based on the proposed operations on the tree of the statement or signature. Then, we classify the changes according to action type, entity kind, element kind and pattern kind. Based on the current implementation, we applied it to four open Java projects. Through the case study, we validated that the taxonomy can classify changes in all the modified statements and signatures. And, we checked the proportions of change patterns. Furthermore, we demonstrated that it is easy to find out the rename-induced statement updates with the help of the taxonomy. As a result, this taxonomy can be used for further change understanding and change analysis.