Summarizing Code Changes by Tracing an Operation History Graph

By replaying the edit history of source code, the changes in software can be precisely understood. Recently, several replay tools have been proposed to support developers' tasks of understanding past code changes. However, replaying is still a time-consuming task due to a plethora of the edit operations. This paper proposes a novel method to generate a summary of edit histories. The method is supposed to be used before replaying with existing tools to easily find which part is important for the current understanding task. This paper also introduces OpG2, which is a graph format that represents change histories at code and syntax levels. We can easily summarize edit operations by tracing edges in the graph. A case study shows an example of the summarization process using an operation history derived from an actual software development.