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/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008 Sun Microsystems
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
*
* Structures and functions for:
*
* Calculating day number in Gregorian and Julian proleptic calendars.
* Converting between day numbers and dates in the calendars.
* Converting between different calendars.
* Calculating differences between dates.
*
* Works used in research:
*
* @cite "Calendrical Calculations", Dershowitz and Reingold
* @cite ISO 8601 http://en.wikipedia.org/wiki/ISO_8601
* @cite http://www.ddj.com/hpc-high-performance-computing/197006254
* @cite http://en.wikipedia.org/wiki/Julian_day#Calculation
*/
#ifndef DRIZZLED_CALENDAR_H
#define DRIZZLED_CALENDAR_H
#define JULIAN_DAY_NUMBER_AT_ABSOLUTE_DAY_ONE INT64_C(1721425)
#define DAYS_IN_NORMAL_YEAR INT32_C(365)
#define DAYS_IN_LEAP_YEAR INT32_C(366)
#define GREGORIAN_START_YEAR 1582
#define GREGORIAN_START_MONTH 10
#define GREGORIAN_START_DAY 15
#define UNIX_EPOCH_MAX_YEARS 2038
#define UNIX_EPOCH_MIN_YEARS 1970
/**
* The following constants define the system of calculating the number
* of days in various periods of time in the Gregorian calendar.
*
* Leap years (years containing 366 days) occur:
*
* - When the year is evenly divisible by 4
* - If the year is evenly divisible by 100, it must also
* be evenly divisible by 400.
*/
#define GREGORIAN_DAYS_IN_400_YEARS UINT32_C(146097)
#define GREGORIAN_DAYS_IN_100_YEARS UINT32_C(36524)
#define GREGORIAN_DAYS_IN_4_YEARS UINT32_C(1461)
/**
* Simple macro returning whether the supplied year
* is a leap year in the supplied calendar.
*
* @param Year to evaluate
* @param Calendar to use
*/
#define IS_LEAP_YEAR(y, c) (days_in_year((y),(c)) == 366)
/**
* Simple macro returning whether the supplied year
* is a leap year in the Gregorian proleptic calendar.
*/
#define IS_GREGORIAN_LEAP_YEAR(y) (days_in_year_gregorian((y)) == 366)
/**
* Simple macro returning whether the supplied year
* is a leap year in the Julian proleptic calendar.
*/
#define IS_JULIAN_LEAP_YEAR(y) (days_in_year_julian((y)) == 366)
#ifdef __cplusplus
extern "C" {
#endif
/**
* Different calendars supported by the temporal library
*/
enum calendar
{
GREGORIAN= 1
, JULIAN= 2
, HEBREW= 3
, ISLAM= 4
};
/**
* Calculates the Julian Day Number from the year, month
* and day supplied for a Gregorian Proleptic calendar date.
*
* @note
*
* Year month and day values are assumed to be valid. This
* method does no bounds checking or validation.
*
* @param Year of date
* @param Month of date
* @param Day of date
*/
int64_t julian_day_number_from_gregorian_date(uint32_t year, uint32_t month, uint32_t day);
/**
* Translates an absolute day number to a
* Julian day number.
*
* @param The absolute day number
*/
int64_t absolute_day_number_to_julian_day_number(int64_t absolute_day);
/**
* Translates a Julian day number to an
* absolute day number.
*
* @param The Julian day number
*/
int64_t julian_day_number_to_absolute_day_number(int64_t julian_day);
/**
* Given a supplied Julian Day Number, populates a year, month, and day
* with the date in the Gregorian Proleptic calendar which corresponds to
* the given Julian Day Number.
*
* @param Julian Day Number
* @param Pointer to year to populate
* @param Pointer to month to populate
* @param Pointer to the day to populate
*/
void gregorian_date_from_julian_day_number(int64_t julian_day
, uint32_t *year_out
, uint32_t *month_out
, uint32_t *day_out);
/**
* Given a supplied Absolute Day Number, populates a year, month, and day
* with the date in the Gregorian Proleptic calendar which corresponds to
* the given Absolute Day Number.
*
* @param Absolute Day Number
* @param Pointer to year to populate
* @param Pointer to month to populate
* @param Pointer to the day to populate
*/
void gregorian_date_from_absolute_day_number(int64_t absolute_day
, uint32_t *year_out
, uint32_t *month_out
, uint32_t *day_out);
/**
* Returns the number of days in a particular year.
*
* @param year to evaluate
* @param calendar to use
*/
uint32_t days_in_year(uint32_t year, enum calendar calendar);
/**
* Returns the number of days in a particular Gregorian Proleptic calendar year.
*
* @param year to evaluate
*/
uint32_t days_in_year_gregorian(uint32_t year);
/**
* Returns the number of days in a particular Julian Proleptic calendar year.
*
* @param year to evaluate
*/
uint32_t days_in_year_julian(uint32_t year);
#define NUM_LEAP_YEARS(y, c) ((c) == GREGORIAN \
? number_of_leap_years_gregorian((y)) \
: number_of_leap_years_julian((y)))
/**
* Returns the number of leap years that have
* occurred in the Julian Proleptic calendar
* up to the supplied year.
*
* @param year to evaluate (1 - 9999)
*/
int32_t number_of_leap_years_julian(uint32_t year);
/**
* Returns the number of leap years that have
* occurred in the Gregorian Proleptic calendar
* up to the supplied year.
*
* @param year to evaluate (1 - 9999)
*/
int32_t number_of_leap_years_gregorian(uint32_t year);
/**
* Returns the number of days in a month, given
* a year and a month in the Gregorian calendar.
*
* @param Year in Gregorian Proleptic calendar
* @param Month in date
*/
uint32_t days_in_gregorian_year_month(uint32_t year, uint32_t month);
/**
* Returns the number of the day in a week.
*
* @see temporal_to_number_days()
*
* Return values:
*
* Day Day Number Sunday first day?
* -------------- ----------- -----------------
* Sunday 0 true
* Monday 1 true
* Tuesday 2 true
* Wednesday 3 true
* Thursday 4 true
* Friday 5 true
* Saturday 6 true
* Sunday 6 false
* Monday 0 false
* Tuesday 1 false
* Wednesday 2 false
* Thursday 3 false
* Friday 4 false
* Saturday 5 false
*
* @param Number of days since start of Gregorian calendar.
* @param Consider Sunday the first day of the week?
*/
uint32_t day_of_week(int64_t day_number, bool sunday_is_first_day_of_week);
/**
* Given a year, month, and day, returns whether the date is
* valid for the Gregorian proleptic calendar.
*
* @param The year
* @param The month
* @param The day
*/
bool is_valid_gregorian_date(uint32_t year, uint32_t month, uint32_t day);
/**
* Returns whether the supplied date components are within the
* range of the UNIX epoch.
*
* Times in the range of 1970-01-01T00:00:00 to 2038-01-19T03:14:07
*
* @param Year
* @param Month
* @param Day
* @param Hour
* @param Minute
* @param Second
*/
bool in_unix_epoch_range(uint32_t year
, uint32_t month
, uint32_t day
, uint32_t hour
, uint32_t minute
, uint32_t second);
/**
* Returns the number of the week from a supplied year, month, and
* date in the Gregorian proleptic calendar. We use strftime() and
* the %U, %W, and %V format specifiers depending on the value
* of the sunday_is_first_day_of_week parameter.
*
* @param Subject year
* @param Subject month
* @param Subject day
* @param Is sunday the first day of the week?
* @param Pointer to a uint32_t to hold the resulting year, which
* may be incremented or decremented depending on flags
*/
uint32_t week_number_from_gregorian_date(uint32_t year
, uint32_t month
, uint32_t day
, bool sunday_is_first_day_of_week);
/**
* Returns the ISO week number of a supplied year, month, and
* date in the Gregorian proleptic calendar. We use strftime() and
* the %V format specifier to do the calculation, which yields a
* correct ISO 8601:1988 week number.
*
* The final year_out parameter is a pointer to an integer which will
* be set to the year in which the week belongs, according to ISO8601:1988,
* which may be different from the Gregorian calendar year.
*
* @see http://en.wikipedia.org/wiki/ISO_8601
*
* @param Subject year
* @param Subject month
* @param Subject day
* @param Pointer to a uint32_t to hold the resulting year, which
* may be incremented or decremented depending on flags
*/
uint32_t iso_week_number_from_gregorian_date(uint32_t year
, uint32_t month
, uint32_t day
, uint32_t *year_out);
#ifdef __cplusplus
}
#endif
#endif /* DRIZZLED_CALENDAR_H */
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