Chris@16: /* Copyright (c) 2002,2003 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: #ifndef NO_BOOST_DATE_TIME_INLINE
Chris@16:   #undef BOOST_DATE_TIME_INLINE
Chris@16:   #define BOOST_DATE_TIME_INLINE inline
Chris@16: #endif
Chris@16: 
Chris@16: namespace boost {
Chris@16: namespace date_time {
Chris@16:   //! Return the day of the week (0==Sunday, 1==Monday, etc)
Chris@16:   /*! Converts a year-month-day into a day of the week number
Chris@16:    */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   unsigned short
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::day_of_week(const ymd_type& ymd) {
Chris@16:     unsigned short a = static_cast<unsigned short>((14-ymd.month)/12);
Chris@16:     unsigned short y = static_cast<unsigned short>(ymd.year - a);
Chris@16:     unsigned short m = static_cast<unsigned short>(ymd.month + 12*a - 2);
Chris@16:     unsigned short d = static_cast<unsigned short>((ymd.day + y + (y/4) - (y/100) + (y/400) + (31*m)/12) % 7);
Chris@16:     //std::cout << year << "-" << month << "-" << day << " is day: " << d << "\n";
Chris@16:     return d;
Chris@16:   }
Chris@16: 
Chris@16:   //!Return the iso week number for the date
Chris@16:   /*!Implements the rules associated with the iso 8601 week number.
Chris@16:     Basically the rule is that Week 1 of the year is the week that contains
Chris@16:     January 4th or the week that contains the first Thursday in January.
Chris@16:     Reference for this algorithm is the Calendar FAQ by Claus Tondering, April 2000.
Chris@16:   */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   int
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::week_number(const ymd_type& ymd) {
Chris@16:     unsigned long julianbegin = julian_day_number(ymd_type(ymd.year,1,1));
Chris@16:     unsigned long juliantoday = julian_day_number(ymd);
Chris@16:     unsigned long day = (julianbegin + 3) % 7;
Chris@16:     unsigned long week = (juliantoday + day - julianbegin + 4)/7;
Chris@16: 
Chris@16:     if ((week >= 1) && (week <= 52)) {
Chris@16:       return week;
Chris@16:     }
Chris@16: 
Chris@16:     if (week == 53) {
Chris@16:       if((day==6) ||(day == 5 && is_leap_year(ymd.year))) {
Chris@16:         return week; //under these circumstances week == 53.
Chris@16:       } else {
Chris@16:         return 1; //monday - wednesday is in week 1 of next year
Chris@16:       }
Chris@16:     }
Chris@16:     //if the week is not in current year recalculate using the previous year as the beginning year
Chris@16:     else if (week == 0) {
Chris@16:       julianbegin = julian_day_number(ymd_type(static_cast<unsigned short>(ymd.year-1),1,1));
Chris@16:       juliantoday = julian_day_number(ymd);
Chris@16:       day = (julianbegin + 3) % 7;
Chris@16:       week = (juliantoday + day - julianbegin + 4)/7;
Chris@16:       return week;
Chris@16:     }
Chris@16: 
Chris@16:     return week;  //not reachable -- well except if day == 5 and is_leap_year != true
Chris@16: 
Chris@16:   }
Chris@16: 
Chris@16:   //! Convert a ymd_type into a day number
Chris@16:   /*! The day number is an absolute number of days since the start of count
Chris@16:    */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   date_int_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::day_number(const ymd_type& ymd)
Chris@16:   {
Chris@16:     unsigned short a = static_cast<unsigned short>((14-ymd.month)/12);
Chris@16:     unsigned short y = static_cast<unsigned short>(ymd.year + 4800 - a);
Chris@16:     unsigned short m = static_cast<unsigned short>(ymd.month + 12*a - 3);
Chris@16:     unsigned long  d = ymd.day + ((153*m + 2)/5) + 365*y + (y/4) - (y/100) + (y/400) - 32045;
Chris@16:     return d;
Chris@16:   }
Chris@16: 
Chris@16:   //! Convert a year-month-day into the julian day number
Chris@16:   /*! Since this implementation uses julian day internally, this is the same as the day_number.
Chris@16:    */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   date_int_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::julian_day_number(const ymd_type& ymd)
Chris@16:   {
Chris@16:     return day_number(ymd);
Chris@16:   }
Chris@16: 
Chris@16:   //! Convert year-month-day into a modified julian day number
Chris@16:   /*! The day number is an absolute number of days.
Chris@16:    *  MJD 0 thus started on 17 Nov 1858(Gregorian) at 00:00:00 UTC
Chris@16:    */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   date_int_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::modjulian_day_number(const ymd_type& ymd)
Chris@16:   {
Chris@16:     return julian_day_number(ymd)-2400001; //prerounded
Chris@16:   }
Chris@16: 
Chris@16:   //! Change a day number into a year-month-day
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   ymd_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::from_day_number(date_int_type dayNumber)
Chris@16:   {
Chris@16:     date_int_type a = dayNumber + 32044;
Chris@16:     date_int_type b = (4*a + 3)/146097;
Chris@16:     date_int_type c = a-((146097*b)/4);
Chris@16:     date_int_type d = (4*c + 3)/1461;
Chris@16:     date_int_type e = c - (1461*d)/4;
Chris@16:     date_int_type m = (5*e + 2)/153;
Chris@16:     unsigned short day = static_cast<unsigned short>(e - ((153*m + 2)/5) + 1);
Chris@16:     unsigned short month = static_cast<unsigned short>(m + 3 - 12 * (m/10));
Chris@16:     year_type year = static_cast<unsigned short>(100*b + d - 4800 + (m/10));
Chris@16:     //std::cout << year << "-" << month << "-" << day << "\n";
Chris@16: 
Chris@16:     return ymd_type(static_cast<unsigned short>(year),month,day);
Chris@16:   }
Chris@16: 
Chris@16:   //! Change a day number into a year-month-day
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   ymd_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::from_julian_day_number(date_int_type dayNumber)
Chris@16:   {
Chris@16:     date_int_type a = dayNumber + 32044;
Chris@16:     date_int_type b = (4*a+3)/146097;
Chris@16:     date_int_type c = a - ((146097*b)/4);
Chris@16:     date_int_type d = (4*c + 3)/1461;
Chris@16:     date_int_type e = c - ((1461*d)/4);
Chris@16:     date_int_type m = (5*e + 2)/153;
Chris@16:     unsigned short day = static_cast<unsigned short>(e - ((153*m + 2)/5) + 1);
Chris@16:     unsigned short month = static_cast<unsigned short>(m + 3 - 12 * (m/10));
Chris@16:     year_type year = static_cast<year_type>(100*b + d - 4800 + (m/10));
Chris@16:     //std::cout << year << "-" << month << "-" << day << "\n";
Chris@16: 
Chris@16:     return ymd_type(year,month,day);
Chris@16:   }
Chris@16: 
Chris@16:   //! Change a modified julian day number into a year-month-day
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   ymd_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::from_modjulian_day_number(date_int_type dayNumber) {
Chris@16:     date_int_type jd = dayNumber + 2400001; //is 2400000.5 prerounded
Chris@16:     return from_julian_day_number(jd);
Chris@16:   }
Chris@16: 
Chris@16:   //! Determine if the provided year is a leap year
Chris@16:   /*!
Chris@16:    *@return true if year is a leap year, false otherwise
Chris@16:    */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   bool
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::is_leap_year(year_type year)
Chris@16:   {
Chris@16:     //divisible by 4, not if divisible by 100, but true if divisible by 400
Chris@16:     return (!(year % 4))  && ((year % 100) || (!(year % 400)));
Chris@16:   }
Chris@16: 
Chris@16:   //! Calculate the last day of the month
Chris@16:   /*! Find the day which is the end of the month given year and month
Chris@16:    *  No error checking is performed.
Chris@16:    */
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   unsigned short
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::end_of_month_day(year_type year,
Chris@16:                                                                       month_type month)
Chris@16:   {
Chris@16:     switch (month) {
Chris@16:     case 2:
Chris@16:       if (is_leap_year(year)) {
Chris@16:         return 29;
Chris@16:       } else {
Chris@16:         return 28;
Chris@16:       };
Chris@16:     case 4:
Chris@16:     case 6:
Chris@16:     case 9:
Chris@16:     case 11:
Chris@16:       return 30;
Chris@16:     default:
Chris@16:       return 31;
Chris@16:     };
Chris@16: 
Chris@16:   }
Chris@16: 
Chris@16:   //! Provide the ymd_type specification for the calandar start
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   ymd_type_
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::epoch()
Chris@16:   {
Chris@16:     return ymd_type(1400,1,1);
Chris@16:   }
Chris@16: 
Chris@16:   //! Defines length of a week for week calculations
Chris@16:   template<typename ymd_type_, typename date_int_type_>
Chris@16:   BOOST_DATE_TIME_INLINE
Chris@16:   unsigned short
Chris@16:   gregorian_calendar_base<ymd_type_,date_int_type_>::days_in_week()
Chris@16:   {
Chris@16:     return 7;
Chris@16:   }
Chris@16: 
Chris@16: 
Chris@16: } } //namespace gregorian
Chris@16: 
Chris@16: