Structural clones: An evolution perspective

Structural clones are recurring patterns of simple code clones in software that represent a bigger picture of similarity in software (e.g. software design). Elevating the analysis of cloning to structural clone level helps in better clone management in terms of clone understanding, maintenance and evolution. In this paper, we propose a systematic approach to study structural clone evolution in software versions. We use our approach to analyze the evolutionary behavior of structural clones and also compare it with the evolution of simple clones. We performed experiments on different versions of three Java systems. Our analysis of structural clone evolution reveals interesting evolutionary characteristics of clones. For example, one finding is that simple clones are more frequently changed than structural clones whereas average lifetime of structural clones is less than that of simple clones. Study of clone evolution is helpful for identifying maintenance implications of clones and for devising better clone management systems.