gistfile1.txt

grammar BUU {
    token TOP { <abc>+ };
    token abc { 'a' <bc>* };
    token bc { [ 'b' <c>* ]+ }
    token c { 'c' };
};

class BuuAbc0 {
    method TOP($/) { make $/; }
    method abc($/) { make $/; }
    method bc($/) { make $/; }
    method c($/) { make ~$/;  }
};

my $r = BUU.parse( "abcabccabbccaababc", :actions( BuuAbc0 ) );

#say $r.ast;
say $r;