Precise Version Control of Trees with Line-Based Version Control Systems

ABSTRACT

Version control of tree structures, ubiquitous in software engineering, is typically performed on a textual encoding of the trees, rather than the trees directly. Applying standard line-based diff and merge algorithms to such encodings leads to inaccurate diffs, unnecessary conflicts, and incorrect merges. To address these problems, we propose novel algorithms for computing precise diffs between two versions of a tree and for three-way merging of trees. Unlike most other approaches for version control of structured data, our approach integrates with mainstream version control systems. Our merge algorithm can be customized for specific application domains to further improve merge results. An evaluation of our approach on abstract syntax trees from popular Java projects shows substantially improved merge results compared to Git.

References

1. Altmanninger, K., Schwinger, W., Kotsis, G.: Semantics for accurate conflict detection in SMoVer: specification, detection and presentation by example. IJEIS 61 2010
2. Altmanninger, K., Seidl, M., Wimmer, M.: A survey on model versioning approaches. Int. J. Web Inf. Syst. 53, 271---304 2009
3. Apel, S., Leβenich, O., Lengauer, C.: Structured merge with auto-tuning: balancing precision and performance. In: Proceedings of the 27th IEEE/ACM International Conference on Automated Software Engineering, ASE 2012. ACM 2012
4. Apel, S., Liebig, J., Brandl, B., Lengauer, C., Kästner, C.: Semistructured merge: rethinking merge in revision control systems. In: Proceedings of the 19th ACM SIGSOFT Symposium and the 13th European Conference on Foundations of Software Engineering, ESEC/FSE 2011. ACM 2011
5. Asenov, D., Müller, P.: Envision: A fast and flexible visual code editor with fluid interactions overview. In: 2014 IEEE Symposium on Visual Languages and Human-Centric Computing VL/HCC, July 2014
6. Asenov, D.: Envision: Reinventing the Integrated Development Environment. Ph.D. thesis, ETH Zurich to appear, 2017
7. Dig, D., Manzoor, K., Johnson, R., Nguyen, T.N.: Refactoring-aware configuration management for object-oriented programs. In: 29th International Conference on Software Engineering ICSE 2007, May 2007
8. Ekman, T., Asklund, U.: Refactoring-aware versioning in Eclipse. Electron. Not. Theor. Comput. Sci. 107, 57---69 2004
9. Falleri, J.R., Morandat, F., Blanc, X., Martinez, M., Montperrus, M.: Fine-grained and accurate source code differencing. In: Proceedings of the 29th ACM/IEEE International Conference on Automated Software Engineering, ASE 2014. ACM 2014
10. Fluri, B., Wuersch, M., Pinzger, M., Gall, H.: Change distilling: tree differencing for fine-grained source code change extraction. IEEE Trans. Softw. Eng. 3311, 725---743 2007
11. Ghezzi, G., Würsch, M., Giger, E., Gall, H.C.: An architectural blueprint for a pluggable version control system for software evolution analysis. In: Proceedings of the Second International Workshop on Developing Tools As Plug-Ins, TOPI 2012. IEEE Press 2012
12. Guenat, B.: Tree-based Version Control in Envision. BSc. Thesis, ETH Zurich 2015
13. Kehrer, T., Kelter, U.: Versioning of ordered model element sets. Technical report 2, University of Siegen 2014
14. Koegel, M., Helming, J.: EMFstore: a model repository for EMF models. In: Proceedings of the 32nd ACM/IEEE International Conference on Software Engineering, ICSE 2010, vol. 2. ACM 2010
15. Koegel, M., Herrmannsdoerfer, M., von Wesendonk, O., Helming, J.: Operation-based conflict detection. In: Proceedings of the 1st International Workshop on Model Comparison in Practice, IWMCP 2010 2010
16. Lindholm, T.: A three-way merge for XML documents. In: Proceedings of the 2004 ACM Symposium on Document Engineering, DocEng 2004. ACM 2004
17. Lorenz, D.H., Rosenan, B.: Source code management for projectional editing. In: Proceedings of the 2013 Companion Publication for Conference on Systems, Programming, Languages & Applications: Software for Humanity, SPLASH 2013. ACM 2013
18. Mens, T.: A state-of-the-art survey on software merging. IEEE Trans. Softw. Eng. 285, 449---462 2002
19. Mikhaiel, R., Tsantalis, N., Negara, N., Stroulia, E., Xing, Z.: Differencing UML models: a domain-specific vs. a domain-agnostic method. In: International Summer School on Generative and Transformational Techniques in Software Engineering IV, GTTSE 2011 2013
20. Miller, W., Myers, E.W.: A file comparison program. Softw. Pract. Exp. 1511, 1025---1040 1985
21. Murta, L., Corrêa, C., Prudêncio, J.G., Werner, C.: Towards Odyssey-VCS 2: improvements over a UML-based version control system. In: Proceedings of the 2008 International Workshop on Comparison and Versioning of Software Models, CVSM 2008. ACM 2008
22. Myers, E.W.: An OND difference algorithm and its variations. Algorithmica 11 1986
23. Nguyen, H.V., Nguyen, M.H., Dang, S.C., Kästner, C., Nguyen, T.N.: Detecting semantic merge conflicts with variability-aware execution. In: Proceedings of the 2015 10th Joint Meeting on Foundations of Software Engineering, ESEC/FSE 2015. ACM 2015
24. Nguyen, T., Munson, E., Boyland, J.: An infrastructure for development of object-oriented, multi-level configuration management services. In: Proceedings of the 27th International Conference on Software Engineering, ICSE 2005, May 2005
25. Nguyen, T.T., Nguyen, H.A., Pham, N.H., Nguyen, T.N.: Operation-based, fine-grained version control model for tree-based representation. In: Rosenblum, D.S., Taentzer, G. eds. FASE 2010. LNCS, vol. 6013, pp. 74---90. Springer, Heidelberg 2010.
26. Oliveira, H., Murta, L., Werner, C.: Odyssey-VCS: a flexible version control system for UML model elements. In: Proceedings of the 12th International Workshop on Software Configuration Management, SCM 2005. ACM 2005
27. Protzenko, J., Burckhardt, S., Moskal, M., McClurg, J.: Implementing real-time collaboration in TouchDevelop using AST merges. In: Proceedings of the 3rd International Workshop on Mobile Development Lifecycle, MobileDeLi 2015. ACM 2015
28. Schwägerl, F., Uhrig, S., Westfechtel, B.: A graph-based algorithm for three-way merging of ordered collections in EMF models. Sci. Comput. Program. 113Pt. 1, 51---81 2015. Model Driven Development Selected & extended papers from MODELSWARD 2014
29. Ukkonen, E.: International conference on foundations of computation theory algorithms for approximate string matching. Inf. Control 641, 100---118 1985
30. Voelter, M., Siegmund, J., Berger, T., Kolb, B.: Towards user-friendly projectional editors. In: Combemale, B., Pearce, D.J., Barais, O., Vinju, J.J. eds. SLE 2014. LNCS, vol. 8706, pp. 41---61. Springer, Cham 2014.
31. Westfechtel, B.: A formal approach to three-way merging of EMF models. In: Proceedings of the 1st International Workshop on Model Comparison in Practice, IWMCP 2010. ACM 2010