OCTools is a suite of tools which serve as a plug-in replacement for yacc and lex. The goal
is to provide a (roughly) source compatible tool which can convert yacc and lex
grammars into Objective C output for building parsers that run on MacOS and iOS.

The source kit can be found on GitHub.

Both tools can be compiled on the Macintosh using Xcode, and generate a command-line tool which can be run from the terminal or included into an Xcode project. (Both tools are built in C, so they should be portable to other platforms; however, I haven’t done the port so I’m not sure how successful porting would be.)

The goal of this project was to create Yacc and Lex analogs which generate re-entrant Objective C classes which implement the parsers, and for the Lex analog to use an Objective-C protocol definition for the input file, for maximum flexibility.

More information can be found here: OCTools.