Earley table traversing parsers

Abstract

We present a version of Earley's general parsing algorithm which uses a precomputed table. Our algorithm generates a set based representation of sentence derivations, precomputed components of which are also held in the table. We give experimental results for Java and ANSI C showing that the data structures produced are considerably smaller than the corresponding Earley data structures, and that the algorithm runs faster. The algorithm retains the simplicity of Earley's approach and, without explanatory discussion, takes only about a page to fully specify. This paper contains both motivational discussion, describing a recogniser version of the algorithm first and then its extension to a parser, and a concise, bare, but complete parser specification.