Parser Grammar Engine (PGE)
Parrot subsystem for regular expressions
Compiles regexes into Parrot subroutines that match patterns
Thus, PGE can take a regex pattern like
[ <alpha> | '_' ] \w*
and produce a standalone parrot subroutine to match it in a string.
A parrot utility (Perl6Grammar.pir) compiles libraries of regexes (grammars) into parsers.