$re = '/(?<=::)[^:]+(?=\n|$)/m';
$str = 'ID::ID123
PUBLISHED_TWEET::ABC
DEF
GHI
EMPLOYEE_ID::ID234
TWEET::ABC
DEF
GHI
ID::ID345
TWEET::#@ABC
DEF
GHI@.[]
USER_IDD::ID456
TWEET::google.com
123456789';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php