public function findIn($haystack) : array
    {
        $matches = [];
        call_user_func_array(
            $this->_method,
            [
                sprintf("/%s/%s", $this->_expr, $this->_flags),
                $haystack,
                &$matches,
                $this->_pregMatchFlags ?: null,
            ]
        );

        if (!isset($matches[1]) && isset($matches[0]) && is_array($matches[0])) {
            return $matches[0];
        }

        return $matches;
    }
public function findIn($haystack) : array
    {
        $matches = [];
        call_user_func_array(
            $this->_method,
            [
                sprintf("/%s/%s", $this->_expr, $this->_flags),
                $haystack,
                &$matches,
                $this->_pregMatchFlags ?: null,
            ]
        );

        if (!isset($matches[1]) && isset($matches[0]) && is_array($matches[0])) {
            return $matches[0];
        }

        return $matches;
    }
public function findIn ( $ haystack ) : array { $ matches = [ ] ; call_user_func_array ( $ this -> _method , [ sprintf ( "/%s/%s" , $ this -> _expr , $ this -> _flags ) , $ haystack , & $ matches , $ this -> _pregMatchFlags ? : null , ] ) ; if ( ! isset ( $ matches [ 1 ] ) && isset ( $ matches [ 0 ] ) && is_array ( $ matches [ 0 ] ) ) { return $ matches [ 0 ] ; } return $ matches ; }
execute preg_match, return matches

@param $haystack
execute preg_match return matches