Code Analyses for Refactoring by Source Code Patterns and Logical Queries

Preconditions of refactorings often comprise complex analyses that require a solid formal basis. The bigger the gap between the level of abstraction of the formalism and the actual implementation is, the harder the coding and maintenance of the analysis will be. In this paper we describe a subset of GenTL, a generic analysis and transformation language. It balances the need for expressiveness, high abstractness and ease of use by combining the full power of a logic language with easily accessible definitions of source code patterns. We demonstrate the advantages of GenTL by implementing the analyses developed by Tip, Kiezun and Bäumer for generalizing type constraints [11]. Our implementation needs just a few lines of code that can be directly traced back to the formal rules.