A new method of generating LL(1) lookahead sets

Authors:
K. John Gough
Affiliations:
Queensland Institute of Technology, Brisbane, Australia
Venue:
ACM SIGPLAN Notices
Year:
1985

Citing 3
Cited 1

Efficient Computation of LALR(1) Look-Ahead Sets

ACM Transactions on Programming Languages and Systems (TOPLAS)
Operations on sparse relations

Communications of the ACM
Syntax of Programming Languages: Theory and Practice

Syntax of Programming Languages: Theory and Practice

Improving Gough's LL(1) lookahead generator

ACM SIGPLAN Notices

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Abstract

The purpose of this note is to draw attention to the existence of a new, efficient algorithm for generating the LL(1) lookaheads for the productions of a context-free grammar. The algorithm is related to a classical method, but forms the sets First() and Follow() directly, rather than first forming the inverses.The success of the method depends on the application of an algorithm which forms a set-union on the transitive closure of a relation. This algorithm is the same one used in the DeRemer and Pennello algorithm for generating the LALR lookaheads for bottom-up parsers.A fuller account of the algorithm and its implementation is available in a technical report, Gough [1984].