greg is a re-entrant peg/leg, with some bug fixes.
<http://piumarta.com/software/peg/>

the most comprehensive example of greg usage is in
nagaqueen, an ooc grammar, used in rock, an ooc
compiler written in ooc.
<http://github.com/nddrylliog/nagaqueen>
<http://github.com/nddrylliog/rock>

peg/leg is copyright (c) 2007 by Ian Piumarta
released under an MIT license. as is greg.