Relation-based algorithms for generating SLR(1) and LALR(1) parsers

The authors characterize the lookahead symbols in terms of very simple relations that bring out substantial structural similarities between SLR(1) and LALR(1) lookaheads. They present algorithms for computing SLR(1) and LALR(1) lookahead that are substantially simpler than those currently known. In contrast to existing algorithms which compute a lookahead set for each reduce move, the authors´ algorithms compute all reduce moves that are triggered by each individual terminal symbol. This simplifies considerably both the characterizations and the algorithms. In particular, no expensive set operations are carried out, and no storage of lookahead sets is required.<>