sub parse {
    my ($text,$mode) = @_;
    my $output = "";
    my $stack = [];
    while (length $text) {
        if ($text =~ s/^\[(pic|gallery|audio|video|infobox)=//) {
            my $name = $1;
            # tag
            my $attr = "";
            if ($text =~ s/^([^\[\]]+)//) {
                $attr = $1;
            }
            push @$stack, [$name, $attr, ""];
        }
        else {
            my $out;
            if ($text =~ s/^\[//) {
                $out = "[";
            }
            if ($text =~ s/^\]//) {
                # closing tag
                my $last = pop @$stack;
                my ($name, $attr, $content) = @$last;
                $out = render($mode, $name, $attr, $content);
            }
            else {
                # text
                if ($text =~ s/^([^\[\]]+)//) {
                    $out = $1;
                }
            }
            if (@$stack > 0) {
                $stack->[-1]->[2] .= $out;
            }
            else {
                $output .= $out;
            }
        }
    }
    return $output;
}