$_ = some line;
my @tmp = @actions;
while (@tmp) {
  my ($qr, $ops) = splice @actions, 0, 2;
  if (my @matches = /$qr/) {
    if (not defined $ops) {
      $default->(@matches);
    } elsif (ref $ops eq 'CODE') {
      $ops->(@matches);
    } elsif (ref $ops eq 'ARRAY') {
      $_->(@matches) for @$ops;
    } else { die "bad" }
    last;
  }
}