/* ******************************************************************************** * 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 /** * IslamicCalendar is a subclass of Calendar * 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). *

* 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. *

* 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. *

* There are two main variants of the Islamic calendar in existence. The first * is the civil 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 IslamicCalendar * object. *

* The Islamic religious calendar, however, is based on the observation * 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. *

* 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. *

* 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 setCivil(false) * 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 CIVIL to use the civil calendar, * ASTRONOMICAL to use the astronomical calendar. * @internal */ void setCivil(ECivil beCivil, UErrorCode &status); /** * Returns true if this object is using the fixed-cycle civil * calendar, or false 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.... // /** * CIVIL if this object uses the fixed-cycle Islamic civil calendar, * and ASTRONOMICAL 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: * *

* * 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