Design and Implementation of Semantic Patch Support for the Spoon Java Transformation Engine

Sammanfattning: Software development is more often than not a collaborative process, creating a need for tools and file formats that enable developers to create and share succinct representations of changes to source code in order to facilitate efficient communication. Standard POSIX diffs and patches have long been important parts of the toolkit, but their lack of support for the syntax and semantics of specific programming languages results in limited expressiveness. The Semantic Patch Language (SmPL), introduced in 2006 together with the tool Coccinelle, increases the expressiveness of POSIX-style patches for the C programming language by leveraging support for the syntax and semantics of C. For example, an SmPL patch can specify changes to source code using metavariables that bind arbitrary program variable names, allowing for the specification of transformations involving variable references regardless of what specific variable names appear in programs targeted by the patch. A recent development is Coccinelle4J, a prototype modification of Coccinelle targeting the Java programming language. Coccinelle4J remains based on a toolkit designed for the parsing and modeling of C, adapted to operate on Java source code. The language mismatch of the base toolkit gives rise to limitations. Despite this, Coccinelle4J remains the state of the art for an SmPL targeting Java. In this thesis we lay the foundations for an SmPL for Java based on Spoon, a robust Java metaprogramming toolkit. We qualitatively investigate to which extent the features of SmPL and Coccinelle are generalizable to a Java context, and we implement and evaluate SPOON-SMPL, a prototype SmPL tool for Java based on Spoon. We base the core design of SPOON-SMPL on temporal logic and model checking, heavily inspired by the design of Coccinelle. We find the majority of identified SmPL features to generalize for Java. We quantitatively evaluate SPOON-SMPL by comparing the running time performance to that of Coccinelle4J over a set of six semantic patches with associated real-world project code bases used in an API migration case study originally performed by the authors of Coccinelle4J. Additionally, we compare the running times of SPOON-SMPL to the average build time of each associated project. We find that SPOON-SMPL performs worse than Coccinelle4J, but that the performance remains in a range acceptable for a single developer using inexpensive hardware. Finally, we provide two proposed designs for extensions to SPOON-SMPL along with a set of suggestions for future work. The proposals show that our prototype offers a strong potential to leverage the capabilities of the Spoon library, particularly in providing improved and robust support for certain aspects of Java for which Coccinelle4J provides only limited support.