my $acc =
        qr/(?> \{          (?: (?> \\. | [^\\{}]+ | (??{ $acc }) ) )*   \} )/x;
    my $inlinetag =
        qr/    \{ (\w+): ( (?: (?> \\. | [^\\{}]+ | (??{ $acc }) ) )* ) \}  /x;