Chris@16: #ifndef DATE_TIME_DST_RULES_HPP__
Chris@16: #define DATE_TIME_DST_RULES_HPP__
Chris@16: 
Chris@16: /* Copyright (c) 2002,2003, 2007 CrystalClear Software, Inc.
Chris@16:  * Use, modification and distribution is subject to the 
Chris@16:  * Boost Software License, Version 1.0. (See accompanying
Chris@16:  * file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  * Author: Jeff Garland, Bart Garst
Chris@101:  * $Date$
Chris@16:  */
Chris@16: 
Chris@16: /*! @file dst_rules.hpp
Chris@16:   Contains template class to provide static dst rule calculations
Chris@16: */
Chris@16: 
Chris@16: #include "boost/date_time/date_generators.hpp"
Chris@16: #include "boost/date_time/period.hpp"
Chris@16: #include "boost/date_time/date_defs.hpp"
Chris@16: #include <stdexcept>
Chris@16: 
Chris@16: namespace boost {
Chris@16:   namespace date_time {
Chris@16: 
Chris@16:     enum time_is_dst_result {is_not_in_dst, is_in_dst, 
Chris@16:                              ambiguous, invalid_time_label};
Chris@16: 
Chris@16: 
Chris@16:     //! Dynamic class used to caluclate dst transition information
Chris@16:     template<class date_type_, 
Chris@16:              class time_duration_type_>
Chris@16:     class dst_calculator
Chris@16:     {
Chris@16:     public:
Chris@16:       typedef time_duration_type_ time_duration_type;
Chris@16:       typedef date_type_ date_type;
Chris@16: 
Chris@16:       //! Check the local time offset when on dst start day
Chris@16:       /*! On this dst transition, the time label between
Chris@16:        *  the transition boundary and the boudary + the offset
Chris@16:        *  are invalid times.  If before the boundary then still 
Chris@16:        *  not in dst.  
Chris@16:        *@param time_of_day Time offset in the day for the local time
Chris@16:        *@param dst_start_offset_minutes Local day offset for start of dst
Chris@16:        *@param dst_length_minutes Number of minutes to adjust clock forward
Chris@16:        *@retval status of time label w.r.t. dst
Chris@16:        */
Chris@16:       static time_is_dst_result 
Chris@16:       process_local_dst_start_day(const time_duration_type& time_of_day,
Chris@16:                                   unsigned int dst_start_offset_minutes,
Chris@16:                                   long dst_length_minutes)
Chris@16:       {
Chris@16:         //std::cout << "here" << std::endl;
Chris@16:         if (time_of_day < time_duration_type(0,dst_start_offset_minutes,0)) {
Chris@16:           return is_not_in_dst;
Chris@16:         }
Chris@16:         long offset = dst_start_offset_minutes + dst_length_minutes;
Chris@16:         if (time_of_day >= time_duration_type(0,offset,0)) {
Chris@16:           return is_in_dst;
Chris@16:         }
Chris@16:         return invalid_time_label; 
Chris@16:       }
Chris@16: 
Chris@16:       //! Check the local time offset when on the last day of dst
Chris@16:       /*! This is the calculation for the DST end day.  On that day times
Chris@16:        *  prior to the conversion time - dst_length (1 am in US) are still 
Chris@16:        *  in dst.  Times between the above and the switch time are 
Chris@16:        *  ambiguous.  Times after the start_offset are not in dst.
Chris@16:        *@param time_of_day Time offset in the day for the local time
Chris@16:        *@param dst_end_offset_minutes Local time of day for end of dst
Chris@16:        *@retval status of time label w.r.t. dst
Chris@16:        */
Chris@16:       static time_is_dst_result 
Chris@16:       process_local_dst_end_day(const time_duration_type& time_of_day,
Chris@16:                                 unsigned int dst_end_offset_minutes,
Chris@16:                                 long dst_length_minutes)
Chris@16:       {
Chris@16:         //in US this will be 60 so offset in day is 1,0,0
Chris@16:         int offset = dst_end_offset_minutes-dst_length_minutes;
Chris@16:         if (time_of_day < time_duration_type(0,offset,0)) {
Chris@16:           return is_in_dst;
Chris@16:         }
Chris@16:         if (time_of_day >= time_duration_type(0,dst_end_offset_minutes,0)) {
Chris@16:           return is_not_in_dst;
Chris@16:         }
Chris@16:         return ambiguous;
Chris@16:       }
Chris@16: 
Chris@16:       //! Calculates if the given local time is dst or not
Chris@16:       /*! Determines if the time is really in DST or not.  Also checks for 
Chris@16:        *  invalid and ambiguous.
Chris@16:        *  @param current_day The day to check for dst
Chris@16:        *  @param time_of_day Time offset within the day to check 
Chris@16:        *  @param dst_start_day  Starting day of dst for the given locality
Chris@16:        *  @param dst_start_offset Time offset within day for dst boundary
Chris@16:        *  @param dst_end_day    Ending day of dst for the given locality
Chris@16:        *  @param dst_end_offset Time offset within day given in dst for dst boundary
Chris@16:        *  @param dst_length lenght of dst adjusment
Chris@16:        *  @retval The time is either ambiguous, invalid, in dst, or not in dst
Chris@16:        */
Chris@16:       static time_is_dst_result 
Chris@16:       local_is_dst(const date_type& current_day,
Chris@16:                    const time_duration_type& time_of_day,
Chris@16:                    const date_type& dst_start_day,
Chris@16:                    const time_duration_type& dst_start_offset,
Chris@16:                    const date_type& dst_end_day,
Chris@16:                    const time_duration_type& dst_end_offset,
Chris@16:                    const time_duration_type& dst_length_minutes)
Chris@16:       {
Chris@16:         unsigned int start_minutes = 
Chris@16:           dst_start_offset.hours() * 60 + dst_start_offset.minutes();
Chris@16:         unsigned int end_minutes = 
Chris@16:           dst_end_offset.hours() * 60 + dst_end_offset.minutes();
Chris@16:         long length_minutes =  
Chris@16:           dst_length_minutes.hours() * 60 + dst_length_minutes.minutes();
Chris@16: 
Chris@16:         return local_is_dst(current_day, time_of_day,
Chris@16:                             dst_start_day, start_minutes,
Chris@16:                             dst_end_day, end_minutes,
Chris@16:                             length_minutes);
Chris@16:       }
Chris@16: 
Chris@16:       //! Calculates if the given local time is dst or not
Chris@16:       /*! Determines if the time is really in DST or not.  Also checks for 
Chris@16:        *  invalid and ambiguous.
Chris@16:        *  @param current_day The day to check for dst
Chris@16:        *  @param time_of_day Time offset within the day to check 
Chris@16:        *  @param dst_start_day  Starting day of dst for the given locality
Chris@16:        *  @param dst_start_offset_minutes Offset within day for dst 
Chris@16:        *         boundary (eg 120 for US which is 02:00:00)
Chris@16:        *  @param dst_end_day    Ending day of dst for the given locality
Chris@16:        *  @param dst_end_offset_minutes Offset within day given in dst for dst 
Chris@16:        *         boundary (eg 120 for US which is 02:00:00)
Chris@16:        *  @param dst_length_minutes Length of dst adjusment (eg: 60 for US)
Chris@16:        *  @retval The time is either ambiguous, invalid, in dst, or not in dst
Chris@16:        */
Chris@16:       static time_is_dst_result 
Chris@16:       local_is_dst(const date_type& current_day,
Chris@16:                    const time_duration_type& time_of_day,
Chris@16:                    const date_type& dst_start_day,
Chris@16:                    unsigned int dst_start_offset_minutes,
Chris@16:                    const date_type& dst_end_day,
Chris@16:                    unsigned int dst_end_offset_minutes,
Chris@16:                    long dst_length_minutes)
Chris@16:       {
Chris@16:         //in northern hemisphere dst is in the middle of the year
Chris@16:         if (dst_start_day < dst_end_day) {
Chris@16:           if ((current_day > dst_start_day) && (current_day < dst_end_day)) {
Chris@16:             return is_in_dst;
Chris@16:           }
Chris@16:           if ((current_day < dst_start_day) || (current_day > dst_end_day)) {
Chris@16:             return is_not_in_dst;
Chris@16:           }
Chris@16:         }
Chris@16:         else {//southern hemisphere dst is at begining /end of year
Chris@16:           if ((current_day < dst_start_day) && (current_day > dst_end_day)) {
Chris@16:             return is_not_in_dst;
Chris@16:           }
Chris@16:           if ((current_day > dst_start_day) || (current_day < dst_end_day)) {
Chris@16:             return is_in_dst;
Chris@16:           }
Chris@16:         }
Chris@16: 
Chris@16:         if (current_day == dst_start_day) {
Chris@16:           return process_local_dst_start_day(time_of_day,
Chris@16:                                              dst_start_offset_minutes,
Chris@16:                                              dst_length_minutes);
Chris@16:         }
Chris@16:       
Chris@16:         if (current_day == dst_end_day) {
Chris@16:           return process_local_dst_end_day(time_of_day,
Chris@16:                                            dst_end_offset_minutes,
Chris@16:                                            dst_length_minutes);
Chris@16:         }
Chris@16:         //you should never reach this statement
Chris@16:         return invalid_time_label;
Chris@16:       }
Chris@16: 
Chris@16:     };
Chris@16: 
Chris@16: 
Chris@16:     //! Compile-time configurable daylight savings time calculation engine
Chris@16:     /* This template provides the ability to configure a daylight savings
Chris@16:      * calculation at compile time covering all the cases.  Unfortunately
Chris@16:      * because of the number of dimensions related to daylight savings
Chris@16:      * calculation the number of parameters is high.  In addition, the
Chris@16:      * start and end transition rules are complex types that specify 
Chris@16:      * an algorithm for calculation of the starting day and ending
Chris@16:      * day of daylight savings time including the month and day 
Chris@16:      * specifications (eg: last sunday in October).
Chris@16:      *
Chris@16:      * @param date_type A type that represents dates, typically gregorian::date
Chris@16:      * @param time_duration_type Used for the offset in the day calculations
Chris@16:      * @param dst_traits A set of traits that define the rules of dst 
Chris@16:      *        calculation.  The dst_trait must include the following:
Chris@16:      * start_rule_functor - Rule to calculate the starting date of a
Chris@16:      *                      dst transition (eg: last_kday_of_month).
Chris@16:      * start_day - static function that returns month of dst start for 
Chris@16:      *             start_rule_functor
Chris@16:      * start_month -static function that returns day or day of week for 
Chris@16:      *              dst start of dst
Chris@16:      * end_rule_functor - Rule to calculate the end of dst day.
Chris@16:      * end_day - static fucntion that returns end day for end_rule_functor
Chris@16:      * end_month - static function that returns end month for end_rule_functor
Chris@16:      * 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.
Chris@16:      * 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. 
Chris@16:      * dst_length_minutes - number of minutes that dst shifts clock
Chris@16:      */
Chris@16:     template<class date_type, 
Chris@16:              class time_duration_type,
Chris@16:              class dst_traits>
Chris@16:     class dst_calc_engine
Chris@16:     {
Chris@16:     public:
Chris@16:       typedef typename date_type::year_type year_type;
Chris@16:       typedef typename date_type::calendar_type calendar_type;
Chris@16:       typedef dst_calculator<date_type, time_duration_type> dstcalc;
Chris@16: 
Chris@16:       //! Calculates if the given local time is dst or not
Chris@16:       /*! Determines if the time is really in DST or not.  Also checks for 
Chris@16:        *  invalid and ambiguous.
Chris@16:        *  @retval The time is either ambiguous, invalid, in dst, or not in dst
Chris@16:        */
Chris@16:       static time_is_dst_result local_is_dst(const date_type& d,
Chris@16:                                              const time_duration_type& td) 
Chris@16:       {
Chris@16: 
Chris@16:         year_type y = d.year();
Chris@16:         date_type dst_start = local_dst_start_day(y);
Chris@16:         date_type dst_end   = local_dst_end_day(y);
Chris@16:         return dstcalc::local_is_dst(d,td,
Chris@16:                                      dst_start,
Chris@16:                                      dst_traits::dst_start_offset_minutes(),
Chris@16:                                      dst_end, 
Chris@16:                                      dst_traits::dst_end_offset_minutes(), 
Chris@16:                                      dst_traits::dst_shift_length_minutes());
Chris@16:       
Chris@16:       }
Chris@16: 
Chris@16:       static bool is_dst_boundary_day(date_type d)
Chris@16:       {
Chris@16:         year_type y = d.year();
Chris@16:         return ((d == local_dst_start_day(y)) ||
Chris@16:                 (d == local_dst_end_day(y)));
Chris@16:       }
Chris@16: 
Chris@16:       //! The time of day for the dst transition (eg: typically 01:00:00 or 02:00:00)
Chris@16:       static time_duration_type dst_offset() 
Chris@16:       {
Chris@16:         return time_duration_type(0,dst_traits::dst_shift_length_minutes(),0);
Chris@16:       }
Chris@16: 
Chris@16:       static date_type local_dst_start_day(year_type year)
Chris@16:       {
Chris@16:         return dst_traits::local_dst_start_day(year);      
Chris@16:       }
Chris@16: 
Chris@16:       static date_type local_dst_end_day(year_type year)
Chris@16:       {
Chris@16:         return dst_traits::local_dst_end_day(year);
Chris@16:       }
Chris@16: 
Chris@16: 
Chris@16:     };
Chris@16: 
Chris@16:     //! Depricated: Class to calculate dst boundaries for US time zones
Chris@16:     /* Use dst_calc_engine instead.
Chris@16:      * In 2007 US/Canada DST rules changed
Chris@16:      * (http://en.wikipedia.org/wiki/Energy_Policy_Act_of_2005#Change_to_daylight_saving_time).
Chris@16:      */
Chris@16:     template<class date_type_, 
Chris@16:              class time_duration_type_,
Chris@16:              unsigned int dst_start_offset_minutes=120, //from start of day 
Chris@16:              short dst_length_minutes=60>  //1 hour == 60 min in US
Chris@16:     class us_dst_rules 
Chris@16:     {
Chris@16:     public:
Chris@16:       typedef time_duration_type_ time_duration_type;
Chris@16:       typedef date_type_ date_type;
Chris@16:       typedef typename date_type::year_type year_type;
Chris@16:       typedef typename date_type::calendar_type calendar_type;
Chris@16:       typedef date_time::last_kday_of_month<date_type> lkday;
Chris@16:       typedef date_time::first_kday_of_month<date_type> fkday;
Chris@16:       typedef date_time::nth_kday_of_month<date_type> nkday;
Chris@16:       typedef dst_calculator<date_type, time_duration_type> dstcalc;
Chris@16: 
Chris@16:       //! Calculates if the given local time is dst or not
Chris@16:       /*! Determines if the time is really in DST or not.  Also checks for 
Chris@16:        *  invalid and ambiguous.
Chris@16:        *  @retval The time is either ambiguous, invalid, in dst, or not in dst
Chris@16:        */
Chris@16:       static time_is_dst_result local_is_dst(const date_type& d,
Chris@16:                                              const time_duration_type& td) 
Chris@16:       {
Chris@16: 
Chris@16:         year_type y = d.year();
Chris@16:         date_type dst_start = local_dst_start_day(y);
Chris@16:         date_type dst_end   = local_dst_end_day(y);
Chris@16:         return dstcalc::local_is_dst(d,td,
Chris@16:                                      dst_start,dst_start_offset_minutes,
Chris@16:                                      dst_end, dst_start_offset_minutes, 
Chris@16:                                      dst_length_minutes);
Chris@16:       
Chris@16:       }
Chris@16: 
Chris@16: 
Chris@16:       static bool is_dst_boundary_day(date_type d)
Chris@16:       {
Chris@16:         year_type y = d.year();
Chris@16:         return ((d == local_dst_start_day(y)) ||
Chris@16:                 (d == local_dst_end_day(y)));
Chris@16:       }
Chris@16: 
Chris@16:       static date_type local_dst_start_day(year_type year)
Chris@16:       {
Chris@16:         if (year >= year_type(2007)) {
Chris@16:           //second sunday in march
Chris@16:           nkday ssim(nkday::second, Sunday, gregorian::Mar);
Chris@16:           return ssim.get_date(year);      
Chris@16:         } else {
Chris@16:           //first sunday in april
Chris@16:           fkday fsia(Sunday, gregorian::Apr);
Chris@16:           return fsia.get_date(year);      
Chris@16:         }
Chris@16:       }
Chris@16: 
Chris@16:       static date_type local_dst_end_day(year_type year)
Chris@16:       {
Chris@16:         if (year >= year_type(2007)) {
Chris@16:           //first sunday in november
Chris@16:           fkday fsin(Sunday, gregorian::Nov);
Chris@16:           return fsin.get_date(year);      
Chris@16:         } else {
Chris@16:           //last sunday in october
Chris@16:           lkday lsio(Sunday, gregorian::Oct);
Chris@16:           return lsio.get_date(year);
Chris@16:         }
Chris@16:       }
Chris@16: 
Chris@16:       static time_duration_type dst_offset()
Chris@16:       {
Chris@16:         return time_duration_type(0,dst_length_minutes,0);
Chris@16:       }
Chris@16: 
Chris@16:      private:
Chris@16: 
Chris@16: 
Chris@16:     };
Chris@16: 
Chris@16:     //! Used for local time adjustments in places that don't use dst
Chris@16:     template<class date_type_, class time_duration_type_>
Chris@16:     class null_dst_rules
Chris@16:     {
Chris@16:     public:
Chris@16:       typedef time_duration_type_ time_duration_type;
Chris@16:       typedef date_type_ date_type;
Chris@16: 
Chris@16: 
Chris@16:       //! Calculates if the given local time is dst or not
Chris@16:       /*! @retval Always is_not_in_dst since this is for zones without dst
Chris@16:        */
Chris@16:       static time_is_dst_result local_is_dst(const date_type&, 
Chris@16:                                              const time_duration_type&) 
Chris@16:       {
Chris@16:         return is_not_in_dst;
Chris@16:       }
Chris@16:     
Chris@16:       //! Calculates if the given utc time is in dst
Chris@16:       static time_is_dst_result utc_is_dst(const date_type&, 
Chris@16:                                            const time_duration_type&) 
Chris@16:       {
Chris@16:         return is_not_in_dst;
Chris@16:       }
Chris@16: 
Chris@16:       static bool is_dst_boundary_day(date_type /*d*/)
Chris@16:       {
Chris@16:         return false;
Chris@16:       }
Chris@16: 
Chris@16:       static time_duration_type dst_offset() 
Chris@16:       {
Chris@16:         return time_duration_type(0,0,0);
Chris@16:       }
Chris@16: 
Chris@16:     };
Chris@16: 
Chris@16: 
Chris@16:   } } //namespace date_time
Chris@16: 
Chris@16: 
Chris@16: 
Chris@16: #endif