On Kilbury's modification of Earley's algorithm

Abstract

We improve on J. Kilbury's proposal to interchange “predictor” and “scanner” in Earley's parser. This modification of Earley's parser can trivially be combined with those suggested by S. Graham, M. Harrison, and W. Ruzzo, leading to smaller parse tables and almost the power of lookahead 1. Along these lines we can also obtain Earley-parsers having partial lookahead r ≥ 1, without storing right contexts. Parse trees with shared structure can be stored in the parse tables directly, rather than constructing the trees from “dotted rules."

Tabular Parsing

“…The parse forest representation is originally due to [5], with states of a finite automaton in place of positions in an input string. Parse forests have also been discussed by [7,29,36,21]. Similar ideas were proposed for tree-adjoining grammars by [39,17].…”

Increasing the Applicability of LR Parsing

“…Leermakers (1992) proposes similar changes to some functions in the recursive ascent Earley parser in order to allow hidden left recursion. Similar changes were made by Graham et al (1980) and Leiss (1990) in order to improve the efficiency of Earley parsing. A parsing technique very similar to ours is suggested by Leermakers (1993).…”

A variant of Earley parsing

“…A considerable number of results and applications regarding Earley parsing have been published in the literature. From a theoretical perspective, improvements of the Earley algorithm have been reported in [9], [15] and [16]. Several reformulations of Earley parsing have also been presented.…”