while (pos($_) < length($_)) {
    if (m{ \G (\w+) \s* = \s* (?=\S) }gcx) {
      # key-value pair is fixed-up in post-processing
      push @args [ $1 ];
    } elsif (m{ \G (\w+) (?= \s | \z ) \s* }gcx) {
      push @args, $1;
    } elsif (m{
      \G (['"]) ( \\. | [^\\] )*? \1 (?= \s | \z ) \s*
    }gcxs) {
      (my $quoted = $2) =~ s/\\(.)/$1/g;
      push @args, $quoted;
    } elsif (m{ \G (:) \s+ }) {
      push @args, $1;
    } else {
      die "parsing error\n";
    }
  }
  for (my $i = 0; $i < @args; ++$i) {
    next unless ref $args[$i];
    my $value = splice @args, $i+1, 1;
    die "parsing error\n" if !defined($value) || ref $value;
    $args[$i] = [ $args[$i], $value ];
  }