Function parseFutureRule

c++/src/Timezone.cc:471–475

* Parse the POSIX TZ string. */

   * Parse the POSIX TZ string.
   */
  std::shared_ptr<FutureRule> parseFutureRule(const std::string& ruleString) {
    auto result = std::make_shared<FutureRuleImpl>();
    FutureRuleParser parser(ruleString, dynamic_cast<FutureRuleImpl*>(result.get()));
    return result;
  }

  std::string TimezoneVariant::toString() const {
    std::stringstream buffer;