devel/ragel 6.10_1 DragonFly

Ragel compiles finite state machines from regular languages into runnable C code. Ragel state machines can not only recognize byte sequences as regular expression machines do, but can also execute code at arbitrary points in the recognition of a regular language.

When you wish to write down a regular language you start with some simple regular language and build a bigger one using the regular language operators union, concatenation, kleene star, intersection and subtraction. This is precisely the way you describe to Ragel how to compile your finite state machines. Ragel also understands operators that insert function calls into machines and operators that control any non-determinism in machines.