Bison
Bison is a program that converts the formal description of a computer language grammar into a C language program that can parse the syntax and symbols of that grammar into instructions that the computer can execute. The grammar to be converted must be a Lookahead Left-to-Right (LALR) context-free grammar.
Bison is upward compatible with Yacc, an earlier tool. Bison would typically be used by a C programmer.