$source =~ s/(\[link title:(.*?)\](.*?)\[\/link])/<a href='$3'>$2<\/a>/gi;

##</code><code>##

while ($source =~ s/\G(\[link title:(.*?)\](.*?)\[\/link])/<a href='$3'>$2<\/a>/i) {
  print "complete: $1\ntitle: $2\nurl: $3\n";
}