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SDF is a formalism for the definition of syntax which is comparable to BNF in some respects, but has a wider scope in that it also covers the definition of lexical and abstract syntax. Its design and implementation are tailored towards the language designer who wants to develop new languages as well as implement existing ones in a highly interactive manner.(More)
Sentences of Visual Languages (VLs) may often be regarded as assemblies of pictorial objects with spatial relationships like “above” or “contains” between them, i.e. their representations are a kind of directed graphs. Such a spatial relationship graph is often complemented by a more abstract graph, which provides information about the syntax (and the(More)
An LR-based parser generator for arbitrary context-free grammars is described, which generates parsers by need and processes grammar modifications by updating already existing parsers. We motivate the need for these techniques in the context of interactive language definition environments, present all required algorithms, and give measurements comparing(More)
{ Sentences of visual languages may often be regarded as assemblies of pictorial objects like \circles", \arrows" or \strings" with spatial relations like \above" or \contains" between them, i.e. their underlying structure is a kind of directed graph. Therefore, graph grammars are a natural means for deening the syntax of visual languages. Their main(More)
A substring recognizer for a language <i>L</i> determines whether a string <i>s</i> is a substring of a sentence in <i>L</i>, i.e., <i>substring-recognize(s)</i> succeeds if and only if &amp;exist;<i>v, w</i>: <i>vsw</i> &amp;isin; <i>L</i>. The algorithm for substring recognition presented here accepts general context-free grammars and uses the same parse(More)
syntax graph L graph rewriting spatial relations graph graph rewriting displaying unstructured editing commands pretty printing parsing structured editing commands graphical editor Figure 2: A hybrid editor for the graphical language L amples of graphical programming environments which work according to this model are [13] and [4]. However, just as pure(More)
We consider the representation of a visual speciication within a highly integrated environment which provides specialized support for the associated visual language. We state that such an environment needs to represent a visual speciication at four levels in order to perform its tasks: (1) the physical layout, (2) the pictorial structure, (3) the abstract(More)
It is common practice to specify textual patterns by means of a set of regular expressions and to transform this set into a finite automaton to be used for the scanning of input strings. In many applications, the cost of this preprocessing phase can be amortized over many uses of the constructed automaton. In this paper new techniques for lazy and(More)