220 lines
8.0 KiB
Plaintext
220 lines
8.0 KiB
Plaintext
/* Copyright (c) 2002,2003 CrystalClear Software, Inc.
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* Use, modification and distribution is subject to the
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* Boost Software License, Version 1.0. (See accompanying
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* file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
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* Author: Jeff Garland, Bart Garst
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* $Date$
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*/
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#ifndef NO_BOOST_DATE_TIME_INLINE
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#undef BOOST_DATE_TIME_INLINE
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#define BOOST_DATE_TIME_INLINE inline
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#endif
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namespace boost {
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namespace date_time {
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//! Return the day of the week (0==Sunday, 1==Monday, etc)
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/*! Converts a year-month-day into a day of the week number
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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unsigned short
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gregorian_calendar_base<ymd_type_,date_int_type_>::day_of_week(const ymd_type& ymd) {
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unsigned short a = static_cast<unsigned short>((14-ymd.month)/12);
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unsigned short y = static_cast<unsigned short>(ymd.year - a);
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unsigned short m = static_cast<unsigned short>(ymd.month + 12*a - 2);
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unsigned short d = static_cast<unsigned short>((ymd.day + y + (y/4) - (y/100) + (y/400) + (31*m)/12) % 7);
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//std::cout << year << "-" << month << "-" << day << " is day: " << d << "\n";
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return d;
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}
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//!Return the iso week number for the date
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/*!Implements the rules associated with the iso 8601 week number.
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Basically the rule is that Week 1 of the year is the week that contains
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January 4th or the week that contains the first Thursday in January.
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Reference for this algorithm is the Calendar FAQ by Claus Tondering, April 2000.
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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int
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gregorian_calendar_base<ymd_type_,date_int_type_>::week_number(const ymd_type& ymd) {
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unsigned long julianbegin = julian_day_number(ymd_type(ymd.year,1,1));
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unsigned long juliantoday = julian_day_number(ymd);
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unsigned long day = (julianbegin + 3) % 7;
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unsigned long week = (juliantoday + day - julianbegin + 4)/7;
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if ((week >= 1) && (week <= 52)) {
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return static_cast<int>(week);
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}
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if (week == 53) {
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if((day==6) ||(day == 5 && is_leap_year(ymd.year))) {
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return static_cast<int>(week); //under these circumstances week == 53.
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} else {
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return 1; //monday - wednesday is in week 1 of next year
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}
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}
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//if the week is not in current year recalculate using the previous year as the beginning year
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else if (week == 0) {
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julianbegin = julian_day_number(ymd_type(static_cast<unsigned short>(ymd.year-1),1,1));
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juliantoday = julian_day_number(ymd);
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day = (julianbegin + 3) % 7;
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week = (juliantoday + day - julianbegin + 4)/7;
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return static_cast<int>(week);
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}
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return static_cast<int>(week); //not reachable -- well except if day == 5 and is_leap_year != true
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}
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//! Convert a ymd_type into a day number
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/*! The day number is an absolute number of days since the start of count
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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date_int_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::day_number(const ymd_type& ymd)
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{
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unsigned short a = static_cast<unsigned short>((14-ymd.month)/12);
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unsigned short y = static_cast<unsigned short>(ymd.year + 4800 - a);
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unsigned short m = static_cast<unsigned short>(ymd.month + 12*a - 3);
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unsigned long d = ymd.day + ((153*m + 2)/5) + 365*y + (y/4) - (y/100) + (y/400) - 32045;
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return static_cast<date_int_type>(d);
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}
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//! Convert a year-month-day into the julian day number
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/*! Since this implementation uses julian day internally, this is the same as the day_number.
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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date_int_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::julian_day_number(const ymd_type& ymd)
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{
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return day_number(ymd);
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}
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//! Convert year-month-day into a modified julian day number
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/*! The day number is an absolute number of days.
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* MJD 0 thus started on 17 Nov 1858(Gregorian) at 00:00:00 UTC
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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date_int_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::modjulian_day_number(const ymd_type& ymd)
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{
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return julian_day_number(ymd)-2400001; //prerounded
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}
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//! Change a day number into a year-month-day
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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ymd_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::from_day_number(date_int_type dayNumber)
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{
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date_int_type a = dayNumber + 32044;
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date_int_type b = (4*a + 3)/146097;
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date_int_type c = a-((146097*b)/4);
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date_int_type d = (4*c + 3)/1461;
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date_int_type e = c - (1461*d)/4;
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date_int_type m = (5*e + 2)/153;
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unsigned short day = static_cast<unsigned short>(e - ((153*m + 2)/5) + 1);
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unsigned short month = static_cast<unsigned short>(m + 3 - 12 * (m/10));
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year_type year = static_cast<unsigned short>(100*b + d - 4800 + (m/10));
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//std::cout << year << "-" << month << "-" << day << "\n";
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return ymd_type(static_cast<unsigned short>(year),month,day);
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}
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//! Change a day number into a year-month-day
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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ymd_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::from_julian_day_number(date_int_type dayNumber)
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{
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date_int_type a = dayNumber + 32044;
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date_int_type b = (4*a+3)/146097;
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date_int_type c = a - ((146097*b)/4);
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date_int_type d = (4*c + 3)/1461;
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date_int_type e = c - ((1461*d)/4);
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date_int_type m = (5*e + 2)/153;
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unsigned short day = static_cast<unsigned short>(e - ((153*m + 2)/5) + 1);
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unsigned short month = static_cast<unsigned short>(m + 3 - 12 * (m/10));
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year_type year = static_cast<year_type>(100*b + d - 4800 + (m/10));
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//std::cout << year << "-" << month << "-" << day << "\n";
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return ymd_type(year,month,day);
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}
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//! Change a modified julian day number into a year-month-day
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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ymd_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::from_modjulian_day_number(date_int_type dayNumber) {
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date_int_type jd = dayNumber + 2400001; //is 2400000.5 prerounded
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return from_julian_day_number(jd);
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}
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//! Determine if the provided year is a leap year
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/*!
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*@return true if year is a leap year, false otherwise
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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bool
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gregorian_calendar_base<ymd_type_,date_int_type_>::is_leap_year(year_type year)
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{
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//divisible by 4, not if divisible by 100, but true if divisible by 400
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return (!(year % 4)) && ((year % 100) || (!(year % 400)));
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}
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//! Calculate the last day of the month
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/*! Find the day which is the end of the month given year and month
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* No error checking is performed.
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*/
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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unsigned short
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gregorian_calendar_base<ymd_type_,date_int_type_>::end_of_month_day(year_type year,
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month_type month)
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{
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switch (month) {
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case 2:
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if (is_leap_year(year)) {
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return 29;
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} else {
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return 28;
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};
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case 4:
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case 6:
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case 9:
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case 11:
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return 30;
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default:
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return 31;
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};
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}
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//! Provide the ymd_type specification for the calandar start
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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ymd_type_
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gregorian_calendar_base<ymd_type_,date_int_type_>::epoch()
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{
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return ymd_type(1400,1,1);
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}
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//! Defines length of a week for week calculations
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template<typename ymd_type_, typename date_int_type_>
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BOOST_DATE_TIME_INLINE
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unsigned short
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gregorian_calendar_base<ymd_type_,date_int_type_>::days_in_week()
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{
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return 7;
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}
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} } //namespace gregorian
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