I played around with the Earley parser that used to be used as part of the CPython build process (who’s name I can’t remember off the top of my head) a bunch and with a lot of hacking I got it into a pretty usable state. It isn’t really that easy to hack on because they do a lot of optimization which is probably one of the major reasons they kicked it out of the python repo.

ANTLR does have python as one of the output languages IIRC.

There’s also a flex/bison clone written in python whose name I also can’t remember.

My current favorite parser generator library, Coco/R, has a python 2 implementation which I’ll maybe get around to porting to py3k one of these days, who knows?

But to answer your question I don’t think there’s a go to library on the python side, I’ve played around with a bunch of them and usually just go for re2c/lemon or Coco/R from C(++) since I mainly just poke at these things probably more than I should.

The next time I get a few days with nothing to do I plan to see if I can’t whip up a working lpeg (lua’s peg parser VM library thing) in python. Someone did a port a while ago but it is abandoned and, honestly, not all that good. No offense to the person who did it but you can do some pretty nifty things with the python C-api with some practice.