Efficient Code Clone Management based on Historical Analysis and Refactoring Support

Code clones have recieved great interests in recent years from many researchers, engineers, and practitioners in the field of software engineering. A code clone is defined as a group of code fragments that are identical or similar to one another. Code clones are introduced into source code of software systems by various rea-sons, and the most typical one is code cloning by copy-and-paste operations for reusing existing features. Typical software systems contain a certain amount of code clones because code cloning is a common practice for software developers. The existence of code clones has been regarded as a bad smell for software evo-lution over a period of time because code clones require much attention to be main-tained. Once code clones are introduced into source code, most of them should be consistently maintained. Unintended inconsistencies among code clones have a high risk for introducing bugs in software systems. However, it is not an easy task for developers or maintainers to be aware of all the code clones and maintain all of them consistently, specifically in the case of large software systems. This is