Non-deterministic recursive ascent parsing

  • Authors:
  • René Leermakers

  • Affiliations:
  • Philips Research Laboratories, Eindhoven, The Netherlands

  • Venue:
  • EACL '91 Proceedings of the fifth conference on European chapter of the Association for Computational Linguistics
  • Year:
  • 1991

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Abstract

A purely functional implementation of LR-parsers is given, together with a simple correctness proof. It is presented as a generalization of the recursive descent parser. For non-LR grammars the time-complexity of our parser is cubic if the functions that constitute the parser are implemented as memo-functions, i.e. functions that memorize the results of previous invocations. Memo-functions also facilitate a simple way to construct a very compact representation of the parse forest. For LR(0) grammars, our algorithm is closely related to the recursive ascent parsers recently discovered by Kruseman Aretz [1] and Roberts [2]. Extended CF grammars (grammars with regular expressions at the right hand side) can be parsed with a simple modification of the LR-parser for normal CF grammars.