our $re_terminate  = qr[ \s* (?: : | , | $ ) ]x;
our $re_content    = qr[ \s* \( ( [\[\{] ) (.+) [\]\}]\) $re_terminate ]x;
our $re_nested     = qr[ \( .+ \) ]x;
our $re_serial     = qr[ ( \( .+? \) ) $re_terminate ]x;
our $re_qq         = qr' " ( .+?  ) (?!<\\)" 'x;
our $re_csv        = qr[ \G \s* (?: $re_qq | ( $re_nested ) | ( [^\s:,]+? ) ) $re_terminate ]x;

sub build_structure{
	warn( "Data didn't match spec.", $_[0] )
	, return undef
		unless $_[0] =~ m[$re_content];

	my ($reftype, $content, $chunk, @bits) = ($1, $2);
	my $p = pos($content);
	while( $content =~ m[$re_csv]gc) {
		$chunk = $1||$3||$2||'0';

		if ($chunk =~ m[^ \( [^\(]+? \) ]x) {
			pos($content) = $p;
			$content =~ m[$re_serial]gc;
			$p = pos($content);
			$chunk = $1;
		}

		push @bits, $chunk =~ m[^\(] 
                        ? build_structure( $chunk ) 
                        : $chunk;

	}
	return $reftype eq '[' ? {@bits} : \@bits;
}