/*
********************************************************************************
* Copyright (C) 2003-2009, International Business Machines Corporation
* and others. All Rights Reserved.
******************************************************************************
*
* File ISLAMCAL.H
*
* Modification History:
*
* Date Name Description
* 10/14/2003 srl ported from java IslamicCalendar
*****************************************************************************
*/
#ifndef ISLAMCAL_H
#define ISLAMCAL_H
#include "unicode/utypes.h"
#if !UCONFIG_NO_FORMATTING
#include "unicode/calendar.h"
U_NAMESPACE_BEGIN
/**
* <code>IslamicCalendar</code> is a subclass of <code>Calendar</code>
* that implements the Islamic civil and religious calendars. It
* is used as the civil calendar in most of the Arab world and the
* liturgical calendar of the Islamic faith worldwide. This calendar
* is also known as the "Hijri" calendar, since it starts at the time
* of Mohammed's emigration (or "hijra") to Medinah on Thursday,
* July 15, 622 AD (Julian).
* <p>
* The Islamic calendar is strictly lunar, and thus an Islamic year of twelve
* lunar months does not correspond to the solar year used by most other
* calendar systems, including the Gregorian. An Islamic year is, on average,
* about 354 days long, so each successive Islamic year starts about 11 days
* earlier in the corresponding Gregorian year.
* <p>
* Each month of the calendar starts when the new moon's crescent is visible
* at sunset. However, in order to keep the time fields in this class
* synchronized with those of the other calendars and with local clock time,
* we treat days and months as beginning at midnight,
* roughly 6 hours after the corresponding sunset.
* <p>
* There are two main variants of the Islamic calendar in existence. The first
* is the <em>civil</em> calendar, which uses a fixed cycle of alternating 29-
* and 30-day months, with a leap day added to the last month of 11 out of
* every 30 years. This calendar is easily calculated and thus predictable in
* advance, so it is used as the civil calendar in a number of Arab countries.
* This is the default behavior of a newly-created <code>IslamicCalendar</code>
* object.
* <p>
* The Islamic <em>religious</em> calendar, however, is based on the <em>observation</em>
* of the crescent moon. It is thus affected by the position at which the
* observations are made, seasonal variations in the time of sunset, the
* eccentricities of the moon's orbit, and even the weather at the observation
* site. This makes it impossible to calculate in advance, and it causes the
* start of a month in the religious calendar to differ from the civil calendar
* by up to three days.
* <p>
* Using astronomical calculations for the position of the sun and moon, the
* moon's illumination, and other factors, it is possible to determine the start
* of a lunar month with a fairly high degree of certainty. However, these
* calculations are extremely complicated and thus slow, so most algorithms,
* including the one used here, are only approximations of the true astronical
* calculations. At present, the approximations used in this class are fairly
* simplistic; they will be improved in later versions of the code.
* <p>
* The {@link #setCivil setCivil} method determines
* which approach is used to determine the start of a month. By default, the
* fixed-cycle civil calendar is used. However, if <code>setCivil(false)</code>
* is called, an approximation of the true lunar calendar will be used.
*
* @see GregorianCalendar
*
* @author Laura Werner
* @author Alan Liu
* @author Steven R. Loomis
* @internal
*/
class IslamicCalendar : public Calendar {
public:
//-------------------------------------------------------------------------
// Constants...
//-------------------------------------------------------------------------
/**
* Calendar type - civil or religious
* @internal
*/
enum ECivil {
ASTRONOMICAL,
CIVIL
};
/**
* Constants for the months
* @internal
*/
enum EMonths {
/**
* Constant for Muharram, the 1st month of the Islamic year.
* @internal
*/
MUHARRAM = 0,
/**
* Constant for Safar, the 2nd month of the Islamic year.
* @internal
*/
SAFAR = 1,
/**
* Constant for Rabi' al-awwal (or Rabi' I), the 3rd month of the Islamic year.
* @internal
*/
RABI_1 = 2,
/**
* Constant for Rabi' al-thani or (Rabi' II), the 4th month of the Islamic year.
* @internal
*/
RABI_2 = 3,
/**
* Constant for Jumada al-awwal or (Jumada I), the 5th month of the Islamic year.
* @internal
*/
JUMADA_1 = 4,
/**
* Constant for Jumada al-thani or (Jumada II), the 6th month of the Islamic year.
* @internal
*/
JUMADA_2 = 5,
/**
* Constant for Rajab, the 7th month of the Islamic year.
* @internal
*/
RAJAB = 6,
/**
* Constant for Sha'ban, the 8th month of the Islamic year.
* @internal
*/
SHABAN = 7,
/**
* Constant for Ramadan, the 9th month of the Islamic year.
* @internal
*/
RAMADAN = 8,
/**
* Constant for Shawwal, the 10th month of the Islamic year.
* @internal
*/
SHAWWAL = 9,
/**
* Constant for Dhu al-Qi'dah, the 11th month of the Islamic year.
* @internal
*/
DHU_AL_QIDAH = 10,
/**
* Constant for Dhu al-Hijjah, the 12th month of the Islamic year.
* @internal
*/
DHU_AL_HIJJAH = 11,
ISLAMIC_MONTH_MAX
};
//-------------------------------------------------------------------------
// Constructors...
//-------------------------------------------------------------------------
/**
* Constructs an IslamicCalendar based on the current time in the default time zone
* with the given locale.
*
* @param aLocale The given locale.
* @param success Indicates the status of IslamicCalendar object construction.
* Returns U_ZERO_ERROR if constructed successfully.
* @param beCivil Whether the calendar should be civil (default-TRUE) or religious (FALSE)
* @internal
*/
IslamicCalendar(const Locale& aLocale, UErrorCode &success, ECivil beCivil = CIVIL);
/**
* Copy Constructor
* @internal
*/
IslamicCalendar(const IslamicCalendar& other);
/**
* Destructor.
* @internal
*/
virtual ~IslamicCalendar();
/**
* Determines whether this object uses the fixed-cycle Islamic civil calendar
* or an approximation of the religious, astronomical calendar.
*
* @param beCivil <code>CIVIL</code> to use the civil calendar,
* <code>ASTRONOMICAL</code> to use the astronomical calendar.
* @internal
*/
void setCivil(ECivil beCivil, UErrorCode &status);
/**
* Returns <code>true</code> if this object is using the fixed-cycle civil
* calendar, or <code>false</code> if using the religious, astronomical
* calendar.
* @internal
*/
UBool isCivil();
// TODO: copy c'tor, etc
// clone
virtual Calendar* clone() const;
private:
/**
* Determine whether a year is a leap year in the Islamic civil calendar
*/
static UBool civilLeapYear(int32_t year);
/**
* Return the day # on which the given year starts. Days are counted
* from the Hijri epoch, origin 0.
*/
int32_t yearStart(int32_t year);
/**
* Return the day # on which the given month starts. Days are counted
* from the Hijri epoch, origin 0.
*
* @param year The hijri year
* @param year The hijri month, 0-based
*/
int32_t monthStart(int32_t year, int32_t month) const;
/**
* Find the day number on which a particular month of the true/lunar
* Islamic calendar starts.
*
* @param month The month in question, origin 0 from the Hijri epoch
*
* @return The day number on which the given month starts.
*/
int32_t trueMonthStart(int32_t month) const;
/**
* Return the "age" of the moon at the given time; this is the difference
* in ecliptic latitude between the moon and the sun. This method simply
* calls CalendarAstronomer.moonAge, converts to degrees,
* and adjusts the resultto be in the range [-180, 180].
*
* @param time The time at which the moon's age is desired,
* in millis since 1/1/1970.
*/
static double moonAge(UDate time, UErrorCode &status);
//-------------------------------------------------------------------------
// Internal data....
//
/**
* <code>CIVIL</code> if this object uses the fixed-cycle Islamic civil calendar,
* and <code>ASTRONOMICAL</code> if it approximates the true religious calendar using
* astronomical calculations for the time of the new moon.
*/
ECivil civil;
//----------------------------------------------------------------------
// Calendar framework
//----------------------------------------------------------------------
protected:
/**
* @internal
*/
virtual int32_t handleGetLimit(UCalendarDateFields field, ELimitType limitType) const;
/**
* Return the length (in days) of the given month.
*
* @param year The hijri year
* @param year The hijri month, 0-based
* @internal
*/
virtual int32_t handleGetMonthLength(int32_t extendedYear, int32_t month) const;
/**
* Return the number of days in the given Islamic year
* @internal
*/
virtual int32_t handleGetYearLength(int32_t extendedYear) const;
//-------------------------------------------------------------------------
// Functions for converting from field values to milliseconds....
//-------------------------------------------------------------------------
// Return JD of start of given month/year
/**
* @internal
*/
virtual int32_t handleComputeMonthStart(int32_t eyear, int32_t month, UBool useMonth) const;
//-------------------------------------------------------------------------
// Functions for converting from milliseconds to field values
//-------------------------------------------------------------------------
/**
* @internal
*/
virtual int32_t handleGetExtendedYear();
/**
* Override Calendar to compute several fields specific to the Islamic
* calendar system. These are:
*
* <ul><li>ERA
* <li>YEAR
* <li>MONTH
* <li>DAY_OF_MONTH
* <li>DAY_OF_YEAR
* <li>EXTENDED_YEAR</ul>
*
* The DAY_OF_WEEK and DOW_LOCAL fields are already set when this
* method is called. The getGregorianXxx() methods return Gregorian
* calendar equivalents for the given Julian day.
* @internal
*/
virtual void handleComputeFields(int32_t julianDay, UErrorCode &status);
// UObject stuff
public:
/**
* @return The class ID for this object. All objects of a given class have the
* same class ID. Objects of other classes have different class IDs.
* @internal
*/
virtual UClassID getDynamicClassID(void) const;
/**
* Return the class ID for this class. This is useful only for comparing to a return
* value from getDynamicClassID(). For example:
*
* Base* polymorphic_pointer = createPolymorphicObject();
* if (polymorphic_pointer->getDynamicClassID() ==
* Derived::getStaticClassID()) ...
*
* @return The class ID for all objects of this class.
* @internal
*/
U_I18N_API static UClassID U_EXPORT2 getStaticClassID(void);
/**
* return the calendar type, "buddhist".
*
* @return calendar type
* @internal
*/
virtual const char * getType() const;
private:
IslamicCalendar(); // default constructor not implemented
// Default century.
protected:
/**
* (Overrides Calendar) Return true if the current date for this Calendar is in
* Daylight Savings Time. Recognizes DST_OFFSET, if it is set.
*
* @param status Fill-in parameter which receives the status of this operation.
* @return True if the current date for this Calendar is in Daylight Savings Time,
* false, otherwise.
* @internal
*/
virtual UBool inDaylightTime(UErrorCode& status) const;
/**
* Returns TRUE because the Islamic Calendar does have a default century
* @internal
*/
virtual UBool haveDefaultCentury() const;
/**
* Returns the date of the start of the default century
* @return start of century - in milliseconds since epoch, 1970
* @internal
*/
virtual UDate defaultCenturyStart() const;
/**
* Returns the year in which the default century begins
* @internal
*/
virtual int32_t defaultCenturyStartYear() const;
private: // default century stuff.
/**
* The system maintains a static default century start date. This is initialized
* the first time it is used. Before then, it is set to SYSTEM_DEFAULT_CENTURY to
* indicate an uninitialized state. Once the system default century date and year
* are set, they do not change.
*/
static UDate fgSystemDefaultCenturyStart;
/**
* See documentation for systemDefaultCenturyStart.
*/
static int32_t fgSystemDefaultCenturyStartYear;
/**
* Default value that indicates the defaultCenturyStartYear is unitialized
*/
static const int32_t fgSystemDefaultCenturyYear;
/**
* start of default century, as a date
*/
static const UDate fgSystemDefaultCentury;
/**
* Returns the beginning date of the 100-year window that dates
* with 2-digit years are considered to fall within.
*/
UDate internalGetDefaultCenturyStart(void) const;
/**
* Returns the first year of the 100-year window that dates with
* 2-digit years are considered to fall within.
*/
int32_t internalGetDefaultCenturyStartYear(void) const;
/**
* Initializes the 100-year window that dates with 2-digit years
* are considered to fall within so that its start date is 80 years
* before the current time.
*/
static void initializeSystemDefaultCentury(void);
};
U_NAMESPACE_END
#endif
#endif