Code Transformation by Direct Transformation of ASTs

Abstract : Software evolves to be adapted to the environment, due to bugs, new features and design changes. Code transformations can be done manually, but that is a tedious and error-prone task. Therefore automated tools are used to assist developers in this maintenance operation. The Pharo environment includes its own refactoring tool — the Rewrite Engine — that allows one to transform methods by directly specifying parts of the AST to be rewritten. In addition, it proposes a parse tree transformation engine. However this tool and the used DSL to express the patterns for matching and transforming trees are complex to understand and master. In this context, writing a transformation rule is not a trivial task. We present a graphical tool built on the top of the Rewrite Engine — the Rewrite Tool — that abstracts the creation of transformation rules and proposes high-level AST operations that are simpler to understand than syntactic descriptions. It helps to automate the process of code transformation with a user-friendly interface.