Survey of Research on Software Clones

This report summarizes my overview talk on software clone detection research. It first discusses the notion of software redundancy, cloning, duplication, and similarity. Then, it describes various categorizations of clone types, empirical studies on the root causes for cloning, current opinions and wisdom of consequences of cloning, empirical studies on the evolution of clones, ways to remove, to avoid, and to detect them, empirical evaluations of existing automatic clone detector performance (such as recall, precision, time and space consumption) and their fitness for a particular purpose, benchmarks for clone detector evaluations, presentation issues, and last but not least application of clone detection in other related fields. After each summary of a subarea, I am listing open research questions

Software Visualization for Reverse Engineering

This article describes the Bauhaus tool suite as a concrete example for software visua-lization in reverse engineering, re-engineering, and software maintenance. Results from a recent survey on software visualization in these domains are reported. According to this survey, Bauhaus can indeed be considered a typical representative of these domains regarding the way software artifacts are visualized. Specific requirements for software visualizations are drawn from both the specific example and the survey.

06301 Abstracts Collection -- Duplication, Redundancy, and Similarity in Software

From 23.07.06 to 26.07.06, the Dagstuhl Seminar 06301 ``Duplication, Redundancy, and Similarity in Software\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Robust Parsing of Cloned Token Sequences

Token-based clone detection techniques are known for theirscalability, high recall, and robustness against syntax errors andincomplete code. They, however, may yield clones that aresyntactically incomplete and they know very little about the syntacticstructure of their reported clones. Hence, their results cannotimmediately be used for automated refactorings or syntactic filtersfor relevance.This paper explores techniques of robust parsing to parse codefragments reported by token-based clone detectors to determine whetherthe clones are syntactically complete and what kind of syntacticelements they contain.This knowledge can be used to improve the precision of token-basedclone detection

Comparison and Evaluation of Clone Detection Tools

Many techniques for detecting duplicated source code (software clones) have been proposed in the past. However, it is not yet clear how these techniques compare in terms of recall and precision as well as space and time requirements. This paper presents an experiment that evaluates six clone detectors based on eight large C and Java programs (altogether almost 850 KLOC). Their clone candidates were evaluated by one of the authors as an independent third party. The selected techniques cover the whole spectrum of the state-of-the-art in clone detection. The techniques work on text, lexical and syntactic information, software metrics, and program dependency graphs

Guest editors’ introduction to the special section from the international conference on software maintenance and evolution

IEEE Transactions on Software Engineering, 33(12): pp. 797-798

Subjectivity in Clone Judgment: Can We Ever Agree?

An objective definition of what a code clone is currently eludes the field. A small study was performed at an international workshop to elicit judgments and discussions from world experts regarding what characteristics define a code clone. Less than half of the clone candidates judged had 80% agreement amongst the judges. Judges appeared to differ primarily in their criteria for judgment rather than their interpretation of the clone candidates. In subsequent open discussion the judges provided several reasons for their judgments. The study casts additional doubt on the reliability of experimental results in the field when the full criterion for clone judgment is not spelled out