I've got a situation where I want to allow users some modest calculation ability, and I've gone through various evolutions of possibilities, like letting them put in raw Clojure code (that I will restrict at some point), to (heh) using POI to let them use Excel to specify possibilities (which is WAY overkill), to using infix.
This is basically what I want, only expandable. I have some reservations, however:
1. It's no longer maintained.
2. It uses the author's own homegrown parser.
3. The comparator operators don't seem to work.
4. There's no function for "I can't calculate this because I don't know the value of X."
All of this is surmountable, of course. The question is, should I surmount it? Or should I just start with Instaparse and a calculator grammar. Or is there a third way?