while ($content =~ /(e)(x)(p)r/g) {
$hash{$1}={ something=>$2, another=>$3 } }

##</code><code>##

my $c=0;
my @subkeys = ('', 'something', 'another', 'third');
my $k;
for ( split(/(?:box)?\n\s*/) ) {
if ($c) { ${$hash{$k}}}{$subkeys[$c]}=$_; }
else {$k = $_ }
$c = ($c + 1)%4;
}