Split a string on a regular expression and also capture the delimiter. This can be useful if you have regular expressions like /(cat|dog|fish)/.
$arr = preg_split($rx, $content, -1, PREG_SPLIT_DELIM_CAPTURE);
for ($i = 0; $i < count($arr); $i+=2) {
$chunk = $arr[0];
$delim = $arr[1];
}