Hm, Bison documentation mentions the ability to declare fixed numeric values for token types:
though with the caveat that:
It is generally best, however, to let Bison choose the numeric codes for all token kinds. Bison will automatically select codes that don’t conflict with each other or with normal characters.
I’m not certain yet what an ideal API for this would like. The other issue right now is that the CS7 AST is slightly different than the CS6 one. It’s been a while since I made changes there but it might be that a CS6 tree might not be valid in CS7.
Maybe that’s moot though; either way, some changes are necessary within Csound to facilitate this, and we’re trying to wrap up CS6 6.16.0 to move on to CS7. I imagine then any public TREE API would be done in CS7. Is having an API for TREE something that you think as a blocker for your project right now? Trying to think about what can be done in terms of scheduling.