A long time ago, I came across Robert Martin's "State Machine Compiler" from his old web site objectmentor.com. The original SMC was in C++ and I thought it would be nice to have something like that in Java. Eventually, someone did make a Java port, but didn't upload the source since, he said, the code was not quite in good enough shape to publish. This was the situation for quite a while.

Many years later as I was looking for a coding exercise topic, I remembered this gap and decided that I should make a java port myself. Once I had it done, though, I realized that the SMC that I had written was itself a state machine and that it should be possible to write the SMC using the SMC itself. So that's what I did and that's the code that's in the "attic" directory. It's in the "attic" becuase the code itself is now a bit dated and am planning to update it to modern java coding standards. I had been again looking for a coding exercise topic (java 9+) and again remembered this bit of code.

There is java code from Mr Martin on sourceforge and github but these seem to have come out much later than the original java port mentioned above. Text of the original article, for the most part, is at smc.txt here on github.

Well, it turns out there wasn't that much to do. Changed some 'Vector's to 'List's, reworked the internal STATE classes a bit and a few other cosmetic changes. To build the smc jar, just checkout the repo, cd into it and run the ./build script. That will bootstrap an smc.jar, generate new Action, Event and FSM classes and rebuild the smc.jar with the newly generated classes. You can sort of see how to use the fsm from the src/smc.java and smc/smcContext.java files. Basically, 'smc' drives the generated Action/Event/FSM code which in turn call into the 'smcContext' for any needed external user-supplied functionality. The simple smc fsm syntax is:

I'll eventually put up a separate example to make usage clearer, most probably the Turnstile example from the oritinal article.