CI_Form_validation::run PHP Method

    public function run($group = '')
    {
        $validation_array = empty($this->validation_data) ? $_POST : $this->validation_data;
        // Does the _field_data array containing the validation rules exist?
        // If not, we look to see if they were assigned via a config file
        if (count($this->_field_data) === 0) {
            // No validation rules?  We're done...
            if (count($this->_config_rules) === 0) {
                return FALSE;
            }
            if (empty($group)) {
                // Is there a validation rule for the particular URI being accessed?
                $group = trim($this->CI->uri->ruri_string(), '/');
                isset($this->_config_rules[$group]) or $group = $this->CI->router->class . '/' . $this->CI->router->method;
            }
            $this->set_rules(isset($this->_config_rules[$group]) ? $this->_config_rules[$group] : $this->_config_rules);
            // Were we able to set the rules correctly?
            if (count($this->_field_data) === 0) {
                log_message('debug', 'Unable to find validation rules');
                return FALSE;
            }
        }
        // Load the language file containing error messages
        $this->CI->lang->load('form_validation');
        // Cycle through the rules for each field and match the corresponding $validation_data item
        foreach ($this->_field_data as $field => &$row) {
            // Fetch the data from the validation_data array item and cache it in the _field_data array.
            // Depending on whether the field name is an array or a string will determine where we get it from.
            if ($row['is_array'] === TRUE) {
                $this->_field_data[$field]['postdata'] = $this->_reduce_array($validation_array, $row['keys']);
            } elseif (isset($validation_array[$field])) {
                $this->_field_data[$field]['postdata'] = $validation_array[$field];
            }
        }
        // Execute validation rules
        // Note: A second foreach (for now) is required in order to avoid false-positives
        //	 for rules like 'matches', which correlate to other validation fields.
        foreach ($this->_field_data as $field => &$row) {
            // Don't try to validate if we have no rules set
            if (empty($row['rules'])) {
                continue;
            }
            $this->_execute($row, $row['rules'], $row['postdata']);
        }
        // Did we end up with any errors?
        $total_errors = count($this->_error_array);
        if ($total_errors > 0) {
            $this->_safe_form_data = TRUE;
        }
        // Now we need to re-set the POST data with the new, processed data
        empty($this->validation_data) && $this->_reset_post_array();
        return $total_errors === 0;
    }

 public function run($group = '') {
     $this->set_rules('nonce', 'Nonce', 'required|valid_nonce');
     $result = parent::run($group);
     if($result === true) {
         $this->save_nonce();
     }
     return $result;
 }