Conceptual Model of the Graphical Editor GENGED for the Visual Definition of Visual Languages

This contribution presents a conceptual model of GENGED, an editor supporting the visual definition of visual languages (VLs). As usual a VL consists of an alphabet and a grammar. Given a grammar of a specific VL GENGED generates a syntax-directed graphical editor allowing the manipulation of visual sentences over this language. The conceptual framework of GENGED is based on algebraic graph transformation and algebraic specification techniques, especially typed algebraic specifications. Starting with a type signature METAVISUAL for visual alphabets, the user of GENGED can define a specific VL-alphabet and some graphical constraints. The VL-alphabet and the constraints are transformed into an algebraic specification whose signature is typed over METAVISUAL. The VL-grammar the user can define on top of the VL-alphabet consists of a start sentence and a set of VL-rules. Each VL-rule is defined by a graph grammar rule and comprises a left– as well as a right-hand-side. Both sides are again visual sentences. Like the VL-alphabet these visual sentences can be transformed into algebraic specifications whose signature is typed over the VL-alphabet. Because the typing is transitiv, all visual sentences are also typed over METAVISUAL. The same is true according to the visual sentences which can be manipulated using a generated graphical editor.