Regex is better for writing parsers.
This is the lexer using solely Perl RegExp (with Perl)
It lexes the C language (context sensitive syntax is also supported - by keeping internal typedef hash)
You can plug it in with the backend (cllvmgen) for a full llvm ir toolchain
You can run either via the backend binary or with the perl interpreter itself
perl ./parse.pl ./bulk/tests/test.c