# ...

    my %taglist_complex = (
        'email' => "<a href='mailto:$1'>$2</a>",
        'url'   => "<a href='$1'>$2</a>",
        'img'   => "<img src='$1' alt='$2' />"
    );
    
    my %taglist_simple = (
        'b' => '<b>$1</b>',
        'i' => '<i>$1</i>',
        'u' => '<u>$1</u>',
        'url' => '<a href=\'$1\'>$1</a>',
        'img' => '<img src=\'$1\' alt=\'$1\' />'
    );

    # Process Complex Tags -> [url="http://www.foo.bar.com"]foobar[/url]
    while (my ($tag, $regex) = each %taglist_complex) {
        $post =~ s/\[\s*$tag\s*=\s*['"]?([\w\W][^\]]*?)['"]?\](.[^\[|\]]*?)\[\s*\/\s*$tag\s*\]/$regex/gi;
    }
    
    # Process Simple Tags -> [url]http://www.foo.bar.com[/url]
    while (my ($tag, $regex) = each %taglist_simple) {
        $post =~ s/\[\s*$tag\s*\](.[^\[|\]]*?)\[\s*\/\s*$tag\s*\]/$regex/gi;
    } 

#...