code: private function parseRules()
      {
          if (null === $this->options['rules']) {
              return $this->getConfig()->getRules();
          }
  
          $rules = trim($this->options['rules']);
          if ('' === $rules) {
              throw new InvalidConfigurationException('Empty rules value is not allowed.');
          }
  
          if ('{' === $rules[0]) {
              $rules = json_decode($rules, true);
              if (JSON_ERROR_NONE !== json_last_error()) {
                  throw new InvalidConfigurationException(sprintf('Invalid JSON rules input: %s.', json_last_error_msg()));
              }
  
              return $rules;
          }
  
          $rules = [];
  
          foreach (explode(',', $this->options['rules']) as $rule) {
              $rule = trim($rule);
              if ('' === $rule) {
                  throw new InvalidConfigurationException('Empty rule name is not allowed.');
              }
  
              if ('-' === $rule[0]) {
                  $rules[substr($rule, 1)] = false;
              } else {
                  $rules[$rule] = true;
              }
          }
  
          return $rules;
      }
docs: Compute rules.
  
  @return array