Beyond GumTree: A Hybrid Approach to Generate Edit Scripts

On development using a version control system, understanding differences of source code is important. Edit scripts (in short, ES) represent differences between two versions of source code. One of the tools generating ESs is GumTree. GumTree takes two versions of source code as input and generates an ES consisting of insert, delete, update and move nodes of abstract syntax tree (in short, AST). However, the accuracy of move and update actions generated by GumTree is insufficient, which makes ESs more difficult to understand. A reason why the accuracy is insufficient is that GumTree generates ESs from only information of AST. Thus, in this research, we propose to generate easier-to-understand ESs by using not only structures of AST but also information of line differences. To evaluate our methodology, we applied it to some open source software, and we confirmed that ESs generated by our methodology are more helpful to understand the differences of source code than GumTree.