using extended positional grammars to develop visual modeling languages
In this paper we present the approach based on the formalism of Extended Positional Grammars for specifying, designing and implementing visual modeling languages. In order to stress the main characteristics of the approach and highlight its power, we describe the use of the formalism to implement statecharts languages which represent one of the most complex visual modeling languages used in the software engineering field. In the paper special emphasis is put on describing the benefits deriving from the use of such formal specifications such as incrementality, easy customization, and automatic generation of visual programming environments. Such features turn out to be especially important because visual modeling languages are subjected to continuous changes as the history of statecharts languages and UML diagrams shows. Moreover, visual languages can be effectively used only if they are supported by a powerful visual environment within they are embedded and used.
extended positional grammars statecharts formal specifications visual languages