HYACC is a full LR(1) parser generator that can also do LALR(1) and LR(0) as well as LR(k) for limited cases.
Hyacc is pronounced as "HiYacc", means Hawaii Yacc. The original web page describing HYACC is here: http://hyacc.sourceforge.net/
The initial commit in this GIT repository is the unaltered code from the HYACC 0.97 source from https://sourceforge.net/projects/hyacc/files/hyacc%200.97/hyacc_unix_src_01_27_2011.tar.gz/download