$re = '/(?:((?(3)\s*|\R*)->\s*([\w.]*(\((?>\'[^\'\\\\]*(?:\\\\.[^\'\\\\]*)*\'|"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"|[^"\'()]++|(?3))*\)))))+\s*\z/';
$str = 'o.start_time = obj.s;
o.repair_type -> obj.r;
o.limit -> obj.l;
->god("(\'\\"\\"\')") ->fox(,\'->\')
->egg()->dog(,\'c\')
->cat(,\'b\')-> banana(,\'a"\\\'\\(\\)\\\'->"()(\') -> apple(,\'a\')';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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