local_date_time.hpp

C++的一个好库。。。现在很流行

    {
      if(zone_ != boost::shared_ptr<tz_type>()){
        utc_time_type lt = this->utc_time() + zone_->base_utc_offset();
        if (is_dst()) {
          lt += zone_->dst_offset();
        }
        return lt;
      }
      return utc_time_type(this->time_);
    }
    //! Returns string in the form "2003-Aug-20 05:00:00 EDT"
    /*! Returns string in the form "2003-Aug-20 05:00:00 EDT". If
     * time_zone is NULL the time zone abbreviation will be "UTC". The time 
     * zone abbrev will not be included if calling object is a special_value*/
    std::string to_string() const
    {
      //TODO is this a temporary function ???
      std::stringstream ss;
      if(this->is_special()){
        ss << utc_time();
        return ss.str();
      }
      if(zone_ == boost::shared_ptr<tz_type>()) {
        ss << utc_time() << " UTC";
        return ss.str();
      }
      bool is_dst_ = is_dst();
      utc_time_type lt = this->utc_time() + zone_->base_utc_offset();
      if (is_dst_) {
        lt += zone_->dst_offset();
      }
      ss << local_time() << " ";
      if (is_dst()) {
        ss << zone_->dst_zone_abbrev();
      }
      else {
        ss << zone_->std_zone_abbrev();
      }
      return ss.str();
    }
    /*! returns a local_date_time_base in the given time zone with the 
     * optional time_duration added. */
    local_date_time_base local_time_in(boost::shared_ptr<tz_type> new_tz, 
                                       time_duration_type td=time_duration_type(0,0,0)) const 
    {
      return local_date_time_base(utc_time_type(this->time_) + td, new_tz);
    }
    
    //! Returns name of associated time zone or "Coordinated Universal Time".
    /*! Optional bool parameter will return time zone as an offset 
     * (ie "+07:00" extended iso format). Empty string is returned for 
     * classes that do not use a time_zone */
    std::string zone_name(bool as_offset=false) const
    {
      if(zone_ == boost::shared_ptr<tz_type>()) {
        if(as_offset) {
          return std::string("Z");
        }
        else {
          return std::string("Coordinated Universal Time");
        }
      }
      if (is_dst()) {
        if(as_offset) {
          time_duration_type td = zone_->base_utc_offset();
          td += zone_->dst_offset();
          return zone_as_offset(td, ":");
        }
        else {
          return zone_->dst_zone_name();
        }
      }
      else {
        if(as_offset) {
          time_duration_type td = zone_->base_utc_offset();
          return zone_as_offset(td, ":");
        }
        else {
          return zone_->std_zone_name();
        }
      }
    }
    //! Returns abbreviation of associated time zone or "UTC".
    /*! Optional bool parameter will return time zone as an offset 
     * (ie "+0700" iso format). Empty string is returned for classes 
     * that do not use a time_zone */
    std::string zone_abbrev(bool as_offset=false) const
    {
      if(zone_ == boost::shared_ptr<tz_type>()) {
        if(as_offset) {
          return std::string("Z");
        }
        else {
          return std::string("UTC");
        }
      }
      if (is_dst()) {
        if(as_offset) {
          time_duration_type td = zone_->base_utc_offset();
          td += zone_->dst_offset();
          return zone_as_offset(td, "");
        }
        else {
          return zone_->dst_zone_abbrev();
        }
      }
      else {
        if(as_offset) {
          time_duration_type td = zone_->base_utc_offset();
          return zone_as_offset(td, "");
        }
        else {
          return zone_->std_zone_abbrev();
        }
      }
    }

    //! returns a posix_time_zone string for the associated time_zone. If no time_zone, "UTC+00" is returned.
    std::string zone_as_posix_string() const
    {
      if(zone_ == shared_ptr<tz_type>()) {
        return std::string("UTC+00");
      }
      return zone_->to_posix_string();
    }
      
    //! Equality comparison operator
    /*bool operator==(const date_time::base_time<boost::posix_time::ptime,boost::posix_time::posix_time_system>& rhs) const
    { // fails due to rhs.time_ being protected
      return date_time::base_time<boost::posix_time::ptime,boost::posix_time::posix_time_system>::operator==(rhs);
      //return this->time_ == rhs.time_;
    }*/
    //! Equality comparison operator
    bool operator==(const local_date_time_base& rhs) const
    {
      return time_system_type::is_equal(this->time_, rhs.time_);
    }
    //! Non-Equality comparison operator
    bool operator!=(const local_date_time_base& rhs) const
    {
      return !(*this == rhs);
    }
    //! Less than comparison operator
    bool operator<(const local_date_time_base& rhs) const
    {
      return time_system_type::is_less(this->time_, rhs.time_);
    }
    //! Less than or equal to comparison operator
    bool operator<=(const local_date_time_base& rhs) const
    {
      return (*this < rhs || *this == rhs);
    }
    //! Greater than comparison operator
    bool operator>(const local_date_time_base& rhs) const
    {
      return !(*this <= rhs);
    }
    //! Greater than or equal to comparison operator
    bool operator>=(const local_date_time_base& rhs) const
    {
      return (*this > rhs || *this == rhs);
    }

    //! Local_date_time + date_duration 
    local_date_time_base operator+(const date_duration_type& dd) const
    {
      return local_date_time_base(time_system_type::add_days(this->time_,dd), zone_);
    }
    //! Local_date_time += date_duration 
    local_date_time_base operator+=(const date_duration_type& dd)
    {
      this->time_ = time_system_type::add_days(this->time_,dd);
      return *this;
    }
    //! Local_date_time - date_duration 
    local_date_time_base operator-(const date_duration_type& dd) const
    {
      return local_date_time_base(time_system_type::subtract_days(this->time_,dd), zone_);
    }
    //! Local_date_time -= date_duration 
    local_date_time_base operator-=(const date_duration_type& dd)
    {
      this->time_ = time_system_type::subtract_days(this->time_,dd);
      return *this;
    }
    //! Local_date_time + time_duration 
    local_date_time_base operator+(const time_duration_type& td) const
    {
      return local_date_time_base(time_system_type::add_time_duration(this->time_,td), zone_);
    }
    //! Local_date_time += time_duration 
    local_date_time_base operator+=(const time_duration_type& td) 
    {
      this->time_ = time_system_type::add_time_duration(this->time_,td);
      return *this;
    }
    //! Local_date_time - time_duration 
    local_date_time_base operator-(const time_duration_type& td) const
    {
      return local_date_time_base(time_system_type::subtract_time_duration(this->time_,td), zone_);
    }
    //! Local_date_time -= time_duration 
    local_date_time_base operator-=(const time_duration_type& td)
    {
      this->time_ = time_system_type::subtract_time_duration(this->time_,td);
      return *this;
    }
    //! local_date_time -= local_date_time --> time_duration_type
    time_duration_type operator-(const local_date_time_base& rhs) const
    {
      return utc_time_type(this->time_) - utc_time_type(rhs.time_);
    }
  private:
    boost::shared_ptr<tz_type> zone_;
    //bool is_dst_;

    /*! Adjust the passed in time to UTC?
     */
    utc_time_type construction_adjustment(utc_time_type t, 
                                          boost::shared_ptr<tz_type> zone,
                                          bool is_dst)
    {
      if(zone != boost::shared_ptr<tz_type>()) {
        if(is_dst && zone->has_dst()) {
          t -= zone->dst_offset();
        } // else no adjust
        t -= zone->base_utc_offset();
      }
      return t;
    }

    /*! Simple formatting code -- todo remove this?
     */
    std::string zone_as_offset(const time_duration_type& td, 
                               const std::string& separator) const
    {
      std::stringstream ss;
      if(td.is_negative()) {
        // a negative duration is represented as "-[h]h:mm"
        // we require two digits for the hour. A positive duration 
        // with the %H flag will always give two digits
        ss << "-";
      }
      else {
        ss << "+";
      }
      ss  << std::setw(2) << std::setfill('0') 
          << date_time::absolute_value(td.hours()) 
          << separator
          << std::setw(2) << std::setfill('0')
          << date_time::absolute_value(td.minutes());
      return ss.str();
    }
  };

  //!Use the default parameters to define local_date_time
  typedef local_date_time_base<> local_date_time;

} }


#endif