$re = '/(?<has_quotes>(?:[^,"\'\n]*(?:(?<double_quotes>"[^"\n]*")|(?<single_quotes>\'[^\'\n]*\'))[^,"\'\n]*)+)|(?<simple>[^,\n]+)/m';
$str = 'a\'b
abcd,efgh, ijkl
abcd, efgh, ij"k,l", mnop, \'q,rs\'t
abcd, efgh, ij"k,l\',a"\', mnop, \'q,r,s\'t
abcd, efgh, ij"k,l", mnop, \'q,rs\'t
\'q, rs\'t
"\'q,rs\'t, ij"k, l""
"\'q,rs\'t, ij"k"\'q,rs\'t, ij"k, l""
';
preg_match_all($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