JDeodorant: Clone Refactoring
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The document discusses a tool for refactoring clones in software. It aims to help developers explore clone groups, inspect differences between clones, and refactor clones safely. The tool detects clones using control structure matching and program dependence graphs. It visualizes clones and differences and automatically determines the best refactoring strategy, such as extract method or introduce utility method. Future work includes supporting more clones, lambda expressions, and testing refactorings. The tool is intended to improve on poor clone refactoring support in current tools.
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JDeodorant: Clone Refactoring
- 1. ICSE’2016 | Austin | May 19, 2016 Davood Mazinanian Nikolaos Tsantalis : Clone Refactoring Raphael Stein Zackary Valenta 1/20 38th International Conference on Software Engineering (ICSE'2016) Formal Tool Demonstration Session Department of Computer Science and Software Engineering Concordia University
- 2. ICSE’2016 | Austin | May 19, 2016 Clones are harmful • Error-prone due to inconsistent updates (Juergens et al. @ ICSE’09) • Increase maintenance effort and cost (Lozano et al. @ ICSM’08) • Change-prone (Mondal et al. @ ACM SAC’12) 2/20
- 3. ICSE’2016 | Austin | May 19, 2016 Clones are good • Positive impact on maintainability (Kasper & Godfrey @ EMSE’08) • Less buggy Less effort to fix bugs (Rahman, Bird & Devanbu @ EMSE’12) 3/20
- 4. ICSE’2016 | Austin | May 19, 2016 Clone management Clones that change frequently & are buggy might need some refactoring 4/20
- 5. ICSE’2016 | Austin | May 19, 2016 Motivation Current clone refactoring support is poor Tairas & Gray (IST’12) studied 1,200 Type-II clones detected in 9 open-source projects: • 10% could be refactored by Eclipse • CeDAR (IST’12) refactored 19% 5/20
- 6. ICSE’2016 | Austin | May 19, 2016 Our goal Help developers: 1. Explore clone groups and understand their relations 2. Inspect and understand the differences between clones 3. Refactor safely the clones 6/20
- 7. ICSE’2016 | Austin | May 19, 2016 7/20
- 8. ICSE’2016 | Austin | May 19, 2016 Clone import 8/20
- 9. ICSE’2016 | Austin | May 19, 2016 Subclone information 9/20
- 10. ICSE’2016 | Austin | May 19, 2016 Clone filtering 10/20
- 11. ICSE’2016 | Austin | May 19, 2016 Clone monitoring 11/20
- 12. ICSE’2016 | Austin | May 19, 2016 12/20
- 13. ICSE’2016 | Austin | May 19, 2016 Our approach common nesting trees if (orientation == VERTICAL) { Line2D line = new Line2D.Double(); double x0 = dataArea.getMinX(); double x1 = dataArea.getMaxX(); g2.setPaint(im.getOutlinePaint()); g2.setStroke(im.getOutlineStroke()); } if (orientation == VERTICAL) { Line2D line = new Line2D.Double(); double x0 = dataArea.getMinX(); double x1 = dataArea.getMaxX(); g2.setPaint(im.getOutlinePaint()); g2.setStroke(im.getOutlineStroke()); } else if(orientation == HORIZONTAL) { Line2D line = new Line2D.Double(); double y0 = dataArea.getMinY(); double y1 = dataArea.getMaxY(); g2.setPaint(im.getOutlinePaint()); g2.setStroke(im.getOutlineStroke()); } Detected clones Control Structure Matching PDG Mapping differences unmapped statements Precondition Examination Refactorable clones 13/20 Assessing the Refactorability of Software Clones, IEEE TSE, Nov. 2015
- 14. ICSE’2016 | Austin | May 19, 2016 Clone pair visualization 14/20
- 15. ICSE’2016 | Austin | May 19, 2016 Semantic tooltips 15/20
- 16. ICSE’2016 | Austin | May 19, 2016 Renamed variables 16/20
- 17. ICSE’2016 | Austin | May 19, 2016 17/20
- 18. ICSE’2016 | Austin | May 19, 2016 Automatic clone refactoring Based on the location of the clones, the best refactoring strategy is automatically determined 1. Extract Method (same file) 2. Pull Up Method (common superclass) a) Template Method (clones call local methods) b) Extract Superclass (external common superclass) 3. Introduce Utility Method (static clones) 18/20
- 19. ICSE’2016 | Austin | May 19, 2016 Refactoring Preview 19/20
- 20. ICSE’2016 | Austin | May 19, 2016 Future work • Support multi-clone refactoring (>2 clones) • Explore lambda expressions • Automated refactoring engine testing 20/20
- 21. ICSE’2016 | Austin | May 19, 2016 Visit our project at http://jdeodorant.org 21/20
- 22. ICSE’2016 | Austin | May 19, 2016 Advanced matches 22/20
- 23. ICSE’2016 | Austin | May 19, 2016 Advanced matches 23/20
Editor's Notes
- so that we don’t have to apply the same changes multiple times.
- The import wizard checks if the clone fragments actually exist in the examined project. And fixes the clone instances that are syntactically incomplete (e.g., missing closing brackets, incomplete statements)
- Group A is a subclone of group B, if every clone instance in A is a subclone (i.e., a partial code fragment) of an instance in B.
- Group A is a subclone of group B, if every clone instance in A is a subclone (i.e., a partial code fragment) of an instance in B.
- In yellow color, we highlight the differences between matched statements. In red color, we highlight the statements that could not be matched. In green color we highlight semantically equivalent statements (statement having a different AST structure, but identical functionality)