$re = '/:\s*\'((?:(?!:\s*\'(?:.*):\s*\'(?:.*)).)+)\'/';
$str = 'required : \'This \'asdf\' "asdf" field is required!\', dateISO : \'This is a test...\', digit : \'Example: This is a plausible use of a colon in a jqValidate message.\', number : \'\'Example\': We probably do not use a colon together with single quotes like this, but we can.\', range : \'Any \'text\' here: This is a very unusual \'portion of text\' - isn\'t it?\', whatever : \'Last \'text\' here: \'Even this combination is possible to use!\'\'';
preg_match_all($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