Diagram editors = graphs + attributes + graph grammars

Abstract

This paper reports on the latest developments in ongoing work which started in 1981 and is aimed at a general method which would help to reduce considerably the time necessary to develop a syntax-directed editor for any given diagram technique. In joint projects between the University of Erlangen-Nürnberg and software companies it has been shown that the ideas and the implemented tools can also be used for the design of CAD-systems. Several editors for diagram techniques in the field of software engineering have been implemented (e.g. SDL and SADT). In addition, 3-D-modelling packages for interior design and furnishing or lighting systems have been developed. The main idea behind the approach is to represent diagrams by (formal) graphs whose nodes are enriched with attributes. Then, any manipulation of a diagram (typically the insertion of an arrow, a box, text, coloring etc.) can be expressed in terms of the manipulation of its underlying attributed representation graph. The formal description of the manipulation is done by programmed attributed graph grammars. The main advantage of using graph grammars is the unified approach for the design of the data structures and the representation of the algorithms as graphs and graph productions, respectively. The results proved that graph grammars are a software-engineering method of their own.