xg is an SLR(1) and LALR(1) parser generator for directly executable (as opposed to table-driven) parsers.
Achyutram Bhamidipaty and Todd A. Proebsting. 1998. Very fast YACC-compatible parsers (for very little effort). Softw. Pract. Exper. 28, 2 (February 1998), 181-190. (link)
R. N. Horspool and M. Whitney. 1990. Even faster LR parsing. Softw. Pract. Exper. 20, 6 (June 1990), 515-535. (link)
Thomas J. Pennello. 1986. Very fast LR parsing. In Proceedings of the 1986 SIGPLAN symposium on Compiler construction (SIGPLAN '86), Richard L Wexelblat (Ed.). ACM, New York, NY, USA, 145-151. (link)