dst_rules.hpp

来自「support vector clustering for vc++」· HPP 代码 · 共 392 行 · 第 1/2 页

     * start_day - static function that returns month of dst start for 
     *             start_rule_functor
     * start_month -static function that returns day or day of week for 
     *              dst start of dst
     * end_rule_functor - Rule to calculate the end of dst day.
     * end_day - static fucntion that returns end day for end_rule_functor
     * end_month - static function that returns end month for end_rule_functor
     * dst_start_offset_minutes - number of minutes from start of day to transition to dst -- 120 (or 2:00 am) is typical for the U.S. and E.U.
     * dst_start_offset_minutes - number of minutes from start of day to transition off of dst -- 180 (or 3:00 am) is typical for E.U. 
     * dst_length_minutes - number of minutes that dst shifts clock
     */
    template<class date_type, 
             class time_duration_type,
             class dst_traits>
    class dst_calc_engine
    {
    public:
      typedef typename date_type::year_type year_type;
      typedef typename date_type::calendar_type calendar_type;
      typedef dst_calculator<date_type, time_duration_type> dstcalc;

      //! Calculates if the given local time is dst or not
      /*! Determines if the time is really in DST or not.  Also checks for 
       *  invalid and ambiguous.
       *  @retval The time is either ambiguous, invalid, in dst, or not in dst
       */
      static time_is_dst_result local_is_dst(const date_type& d,
                                             const time_duration_type& td) 
      {

        year_type y = d.year();
        date_type dst_start = local_dst_start_day(y);
        date_type dst_end   = local_dst_end_day(y);
        return dstcalc::local_is_dst(d,td,
                                     dst_start,
                                     dst_traits::dst_start_offset_minutes(),
                                     dst_end, 
                                     dst_traits::dst_end_offset_minutes(), 
                                     dst_traits::dst_shift_length_minutes());
      
      }

      static bool is_dst_boundary_day(date_type d)
      {
        year_type y = d.year();
        return ((d == local_dst_start_day(y)) ||
                (d == local_dst_end_day(y)));
      }

      //! The time of day for the dst transition (eg: typically 01:00:00 or 02:00:00)
      static time_duration_type dst_offset() 
      {
        return time_duration_type(0,dst_traits::dst_shift_length_minutes(),0);
      }

      static date_type local_dst_start_day(year_type year)
      {
        return dst_traits::local_dst_start_day(year);      
      }

      static date_type local_dst_end_day(year_type year)
      {
        return dst_traits::local_dst_end_day(year);
      }


    };

    //! Depricated: Class to calculate dst boundaries for US time zones
    /* Use dst_calc_engine instead.
     * In 2007 US/Canada DST rules changed
     * (http://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005#Change_to_daylight_saving_time).
     */
    template<class date_type_, 
             class time_duration_type_,
             unsigned int dst_start_offset_minutes=120, //from start of day 
             short dst_length_minutes=60>  //1 hour == 60 min in US
    class us_dst_rules 
    {
    public:
      typedef time_duration_type_ time_duration_type;
      typedef date_type_ date_type;
      typedef typename date_type::year_type year_type;
      typedef typename date_type::calendar_type calendar_type;
      typedef date_time::last_kday_of_month<date_type> lkday;
      typedef date_time::first_kday_of_month<date_type> fkday;
      typedef date_time::nth_kday_of_month<date_type> nkday;
      typedef dst_calculator<date_type, time_duration_type> dstcalc;

      //! Calculates if the given local time is dst or not
      /*! Determines if the time is really in DST or not.  Also checks for 
       *  invalid and ambiguous.
       *  @retval The time is either ambiguous, invalid, in dst, or not in dst
       */
      static time_is_dst_result local_is_dst(const date_type& d,
                                             const time_duration_type& td) 
      {

        year_type y = d.year();
        date_type dst_start = local_dst_start_day(y);
        date_type dst_end   = local_dst_end_day(y);
        return dstcalc::local_is_dst(d,td,
                                     dst_start,dst_start_offset_minutes,
                                     dst_end, dst_start_offset_minutes, 
                                     dst_length_minutes);
      
      }


      static bool is_dst_boundary_day(date_type d)
      {
        year_type y = d.year();
        return ((d == local_dst_start_day(y)) ||
                (d == local_dst_end_day(y)));
      }

      static date_type local_dst_start_day(year_type year)
      {
        if (year >= year_type(2007)) {
          //second sunday in march
          nkday ssim(nkday::second, Sunday, gregorian::Mar);
          return ssim.get_date(year);      
        } else {
          //first sunday in april
          fkday fsia(Sunday, gregorian::Apr);
          return fsia.get_date(year);      
        }
      }

      static date_type local_dst_end_day(year_type year)
      {
        if (year >= year_type(2007)) {
          //first sunday in november
          fkday fsin(Sunday, gregorian::Nov);
          return fsin.get_date(year);      
        } else {
          //last sunday in october
          lkday lsio(Sunday, gregorian::Oct);
          return lsio.get_date(year);
        }
      }

      static time_duration_type dst_offset()
      {
        return time_duration_type(0,dst_length_minutes,0);
      }

     private:


    };

    //! Used for local time adjustments in places that don't use dst
    template<class date_type_, class time_duration_type_>
    class null_dst_rules
    {
    public:
      typedef time_duration_type_ time_duration_type;
      typedef date_type_ date_type;


      //! Calculates if the given local time is dst or not
      /*! @retval Always is_not_in_dst since this is for zones without dst
       */
      static time_is_dst_result local_is_dst(const date_type&, 
                                             const time_duration_type&) 
      {
        return is_not_in_dst;
      }
    
      //! Calculates if the given utc time is in dst
      static time_is_dst_result utc_is_dst(const date_type&, 
                                           const time_duration_type&) 
      {
        return is_not_in_dst;
      }

      static bool is_dst_boundary_day(date_type d)
      {
        return false;
      }

      static time_duration_type dst_offset() 
      {
        return time_duration_type(0,0,0);
      }

    };


  } } //namespace date_time



#endif