SDF is a formalism for the definition of syntax which is comparable to BNF in some respects, but h_ as 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. It emphasizes comP,actness of syntax definitions by offering (a) a standard interface between lexical and context-free syntax; (b) a standard correspondence between context-free and abstract syntax; (c) pow~rful disambiguation and list constructs; and (d) an efficient incremental implementation which accepts arbitrary context-free syntax definitions. SDF can be combined with a variety of progr:amming and specification languages. In this way these obtain fully general user-definable syntax.
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 their performance with that of conventional techniques.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.