$re = '/("{3}|["\'])(?:(?=(\\\\?))\2.)*?\1/s';
$str = '"""
Multi-line text 2 "\'
"""
"String"
"12345"
\'abcde\'
\'It\\\'s\'
"""Multi-line text"""';
preg_match_all($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