co-transformations of grammars and related transformation rules

Despite of their basic role in software development, grammars are still often considered as static artifacts, used for language definition or once prepared for tool construction. Hence, there is insufficient support for working with grammars as software artifacts themselves. However, grammars are permanently changed, e.g. to debug them, to improve languages, to create grammars for tools. In [1] the authors demonstrate, how transformation tasks can be simplified, when underlying grammars are tailored especially to subtasks. The need for a discipline of grammar engineering has been emphasized by [2]. In the following, we will describe two examples of cotransformations. A co-transformation transforms mutually dependent software artifacts of different kinds simultaneously, while the transformation is centred around a grammar (or schema, API, or a similar structure) that is shared among the artifacts [3]. We are interested in consequences of grammar adaptations to transformations based on these grammars, and investigate, if the transformation rules can be migrated to work with the modified grammar.