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 /*

 * Copyright (C) 1997-2013, International Business Machines Corporation and others.

 * All Rights Reserved.

 ********************************************************************************

 *

 * File GREGOCAL.H

 *

 * Modification History:

 *

 *   Date        Name        Description

 *   04/22/97    aliu        Overhauled header.

 *    07/28/98    stephen        Sync with JDK 1.2

 *    09/04/98    stephen        Re-sync with JDK 8/31 putback

 *    09/14/98    stephen        Changed type of kOneDay, kOneWeek to double.

 *                            Fixed bug in roll()

 *   10/15/99    aliu        Fixed j31, incorrect WEEK_OF_YEAR computation.

 *                           Added documentation of WEEK_OF_YEAR computation.

 *   10/15/99    aliu        Fixed j32, cannot set date to Feb 29 2000 AD.

 *                           {JDK bug 4210209 4209272}

 *   11/07/2003  srl         Update, clean up documentation.

 ********************************************************************************

 */

 #ifndef GREGOCAL_H

 #define GREGOCAL_H

 #include "unicode/utypes.h"

 #if !UCONFIG_NO_FORMATTING

 #include "unicode/calendar.h"

 /**

  * \file 

  * \brief C++ API: Concrete class which provides the standard calendar.

  */

 U_NAMESPACE_BEGIN

 /** 

  * Concrete class which provides the standard calendar used by most of the world.

  * <P>

  * The standard (Gregorian) calendar has 2 eras, BC and AD.

  * <P>

  * This implementation handles a single discontinuity, which corresponds by default to

  * the date the Gregorian calendar was originally instituted (October 15, 1582). Not all

  * countries adopted the Gregorian calendar then, so this cutover date may be changed by

  * the caller.

  * <P>

  * Prior to the institution of the Gregorian Calendar, New Year's Day was March 25. To

  * avoid confusion, this Calendar always uses January 1. A manual adjustment may be made

  * if desired for dates that are prior to the Gregorian changeover and which fall

  * between January 1 and March 24.

  *

  * <p>Values calculated for the <code>WEEK_OF_YEAR</code> field range from 1 to

  * 53.  Week 1 for a year is the first week that contains at least

  * <code>getMinimalDaysInFirstWeek()</code> days from that year.  It thus

  * depends on the values of <code>getMinimalDaysInFirstWeek()</code>,

  * <code>getFirstDayOfWeek()</code>, and the day of the week of January 1.

  * Weeks between week 1 of one year and week 1 of the following year are

  * numbered sequentially from 2 to 52 or 53 (as needed).

  *

  * <p>For example, January 1, 1998 was a Thursday.  If

  * <code>getFirstDayOfWeek()</code> is <code>MONDAY</code> and

  * <code>getMinimalDaysInFirstWeek()</code> is 4 (these are the values

  * reflecting ISO 8601 and many national standards), then week 1 of 1998 starts

  * on December 29, 1997, and ends on January 4, 1998.  If, however,

  * <code>getFirstDayOfWeek()</code> is <code>SUNDAY</code>, then week 1 of 1998

  * starts on January 4, 1998, and ends on January 10, 1998; the first three days

  * of 1998 then are part of week 53 of 1997.

  *

  * <p>Example for using GregorianCalendar:

  * <pre>

  * \code

  *     // get the supported ids for GMT-08:00 (Pacific Standard Time)

  *     UErrorCode success = U_ZERO_ERROR;

  *     const StringEnumeration *ids = TimeZone::createEnumeration(-8 * 60 * 60 * 1000);

  *     // if no ids were returned, something is wrong. get out.

  *     if (ids == 0 || ids->count(success) == 0) {

  *         return;

  *     }

  *

  *     // begin output

  *     cout << "Current Time" << endl;

  *

  *     // create a Pacific Standard Time time zone

  *     SimpleTimeZone* pdt = new SimpleTimeZone(-8 * 60 * 60 * 1000, ids->unext(NULL, success)));

  *

  *     // set up rules for daylight savings time

  *     pdt->setStartRule(UCAL_MARCH, 1, UCAL_SUNDAY, 2 * 60 * 60 * 1000);

  *     pdt->setEndRule(UCAL_NOVEMBER, 2, UCAL_SUNDAY, 2 * 60 * 60 * 1000);

  *

  *     // create a GregorianCalendar with the Pacific Daylight time zone

  *     // and the current date and time

  *     Calendar* calendar = new GregorianCalendar( pdt, success );

  *

  *     // print out a bunch of interesting things

  *     cout << "ERA: " << calendar->get( UCAL_ERA, success ) << endl;

  *     cout << "YEAR: " << calendar->get( UCAL_YEAR, success ) << endl;

  *     cout << "MONTH: " << calendar->get( UCAL_MONTH, success ) << endl;

  *     cout << "WEEK_OF_YEAR: " << calendar->get( UCAL_WEEK_OF_YEAR, success ) << endl;

  *     cout << "WEEK_OF_MONTH: " << calendar->get( UCAL_WEEK_OF_MONTH, success ) << endl;

  *     cout << "DATE: " << calendar->get( UCAL_DATE, success ) << endl;

  *     cout << "DAY_OF_MONTH: " << calendar->get( UCAL_DAY_OF_MONTH, success ) << endl;

  *     cout << "DAY_OF_YEAR: " << calendar->get( UCAL_DAY_OF_YEAR, success ) << endl;

  *     cout << "DAY_OF_WEEK: " << calendar->get( UCAL_DAY_OF_WEEK, success ) << endl;

  *     cout << "DAY_OF_WEEK_IN_MONTH: " << calendar->get( UCAL_DAY_OF_WEEK_IN_MONTH, success ) << endl;

  *     cout << "AM_PM: " << calendar->get( UCAL_AM_PM, success ) << endl;

  *     cout << "HOUR: " << calendar->get( UCAL_HOUR, success ) << endl;

  *     cout << "HOUR_OF_DAY: " << calendar->get( UCAL_HOUR_OF_DAY, success ) << endl;

  *     cout << "MINUTE: " << calendar->get( UCAL_MINUTE, success ) << endl;

  *     cout << "SECOND: " << calendar->get( UCAL_SECOND, success ) << endl;

  *     cout << "MILLISECOND: " << calendar->get( UCAL_MILLISECOND, success ) << endl;

  *     cout << "ZONE_OFFSET: " << (calendar->get( UCAL_ZONE_OFFSET, success )/(60*60*1000)) << endl;

  *     cout << "DST_OFFSET: " << (calendar->get( UCAL_DST_OFFSET, success )/(60*60*1000)) << endl;

  *

  *     cout << "Current Time, with hour reset to 3" << endl;

  *     calendar->clear(UCAL_HOUR_OF_DAY); // so doesn't override

  *     calendar->set(UCAL_HOUR, 3);

  *     cout << "ERA: " << calendar->get( UCAL_ERA, success ) << endl;

  *     cout << "YEAR: " << calendar->get( UCAL_YEAR, success ) << endl;

  *     cout << "MONTH: " << calendar->get( UCAL_MONTH, success ) << endl;

  *     cout << "WEEK_OF_YEAR: " << calendar->get( UCAL_WEEK_OF_YEAR, success ) << endl;

  *     cout << "WEEK_OF_MONTH: " << calendar->get( UCAL_WEEK_OF_MONTH, success ) << endl;

  *     cout << "DATE: " << calendar->get( UCAL_DATE, success ) << endl;

  *     cout << "DAY_OF_MONTH: " << calendar->get( UCAL_DAY_OF_MONTH, success ) << endl;

  *     cout << "DAY_OF_YEAR: " << calendar->get( UCAL_DAY_OF_YEAR, success ) << endl;

  *     cout << "DAY_OF_WEEK: " << calendar->get( UCAL_DAY_OF_WEEK, success ) << endl;

  *     cout << "DAY_OF_WEEK_IN_MONTH: " << calendar->get( UCAL_DAY_OF_WEEK_IN_MONTH, success ) << endl;

  *     cout << "AM_PM: " << calendar->get( UCAL_AM_PM, success ) << endl;

  *     cout << "HOUR: " << calendar->get( UCAL_HOUR, success ) << endl;

  *     cout << "HOUR_OF_DAY: " << calendar->get( UCAL_HOUR_OF_DAY, success ) << endl;

  *     cout << "MINUTE: " << calendar->get( UCAL_MINUTE, success ) << endl;

  *     cout << "SECOND: " << calendar->get( UCAL_SECOND, success ) << endl;

  *     cout << "MILLISECOND: " << calendar->get( UCAL_MILLISECOND, success ) << endl;

  *     cout << "ZONE_OFFSET: " << (calendar->get( UCAL_ZONE_OFFSET, success )/(60*60*1000)) << endl; // in hours

  *     cout << "DST_OFFSET: " << (calendar->get( UCAL_DST_OFFSET, success )/(60*60*1000)) << endl; // in hours

  *

  *     if (U_FAILURE(success)) {

  *         cout << "An error occured. success=" << u_errorName(success) << endl;

  *     }

  *

  *     delete ids;

  *     delete calendar; // also deletes pdt

  * \endcode

  * </pre>

  * @stable ICU 2.0

  */

 class U_I18N_API GregorianCalendar: public Calendar {

 public:

     /**

      * Useful constants for GregorianCalendar and TimeZone.

      * @stable ICU 2.0

      */

     enum EEras {

         BC,

         AD

     };

     /**

      * Constructs a default GregorianCalendar using the current time in the default time

      * zone with the default locale.

      *

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(UErrorCode& success);

     /**

      * Constructs a GregorianCalendar based on the current time in the given time zone

      * with the default locale. Clients are no longer responsible for deleting the given

      * time zone object after it's adopted.

      *

      * @param zoneToAdopt     The given timezone.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(TimeZone* zoneToAdopt, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar based on the current time in the given time zone

      * with the default locale.

      *

      * @param zone     The given timezone.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(const TimeZone& zone, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar 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 GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(const Locale& aLocale, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar based on the current time in the given time zone

      * with the given locale. Clients are no longer responsible for deleting the given

      * time zone object after it's adopted.

      *

      * @param zoneToAdopt     The given timezone.

      * @param aLocale  The given locale.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(TimeZone* zoneToAdopt, const Locale& aLocale, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar based on the current time in the given time zone

      * with the given locale.

      *

      * @param zone     The given timezone.

      * @param aLocale  The given locale.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(const TimeZone& zone, const Locale& aLocale, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar with the given AD date set in the default time

      * zone with the default locale.

      *

      * @param year     The value used to set the YEAR time field in the calendar.

      * @param month    The value used to set the MONTH time field in the calendar. Month

      *                 value is 0-based. e.g., 0 for January.

      * @param date     The value used to set the DATE time field in the calendar.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(int32_t year, int32_t month, int32_t date, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar with the given AD date and time set for the

      * default time zone with the default locale.

      *

      * @param year     The value used to set the YEAR time field in the calendar.

      * @param month    The value used to set the MONTH time field in the calendar. Month

      *                 value is 0-based. e.g., 0 for January.

      * @param date     The value used to set the DATE time field in the calendar.

      * @param hour     The value used to set the HOUR_OF_DAY time field in the calendar.

      * @param minute   The value used to set the MINUTE time field in the calendar.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute, UErrorCode& success);

     /**

      * Constructs a GregorianCalendar with the given AD date and time set for the

      * default time zone with the default locale.

      *

      * @param year     The value used to set the YEAR time field in the calendar.

      * @param month    The value used to set the MONTH time field in the calendar. Month

      *                 value is 0-based. e.g., 0 for January.

      * @param date     The value used to set the DATE time field in the calendar.

      * @param hour     The value used to set the HOUR_OF_DAY time field in the calendar.

      * @param minute   The value used to set the MINUTE time field in the calendar.

      * @param second   The value used to set the SECOND time field in the calendar.

      * @param success  Indicates the status of GregorianCalendar object construction.

      *                 Returns U_ZERO_ERROR if constructed successfully.

      * @stable ICU 2.0

      */

     GregorianCalendar(int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute, int32_t second, UErrorCode& success);

     /**

      * Destructor

      * @stable ICU 2.0

      */

     virtual ~GregorianCalendar();

     /**

      * Copy constructor

      * @param source    the object to be copied.

      * @stable ICU 2.0

      */

     GregorianCalendar(const GregorianCalendar& source);

     /**

      * Default assignment operator

      * @param right    the object to be copied.

      * @stable ICU 2.0

      */

     GregorianCalendar& operator=(const GregorianCalendar& right);

     /**

      * Create and return a polymorphic copy of this calendar.

      * @return    return a polymorphic copy of this calendar.

      * @stable ICU 2.0

      */

     virtual Calendar* clone(void) const;

     /**

      * Sets the GregorianCalendar change date. This is the point when the switch from

      * Julian dates to Gregorian dates occurred. Default is 00:00:00 local time, October

      * 15, 1582. Previous to this time and date will be Julian dates.

      *

      * @param date     The given Gregorian cutover date.

      * @param success  Output param set to success/failure code on exit.

      * @stable ICU 2.0

      */

     void setGregorianChange(UDate date, UErrorCode& success);

     /**

      * Gets the Gregorian Calendar change date. This is the point when the switch from

      * Julian dates to Gregorian dates occurred. Default is 00:00:00 local time, October

      * 15, 1582. Previous to this time and date will be Julian dates.

      *

      * @return   The Gregorian cutover time for this calendar.

      * @stable ICU 2.0

      */

     UDate getGregorianChange(void) const;

     /**

      * Return true if the given year is a leap year. Determination of whether a year is

      * a leap year is actually very complicated. We do something crude and mostly

      * correct here, but for a real determination you need a lot of contextual

      * information. For example, in Sweden, the change from Julian to Gregorian happened

      * in a complex way resulting in missed leap years and double leap years between

      * 1700 and 1753. Another example is that after the start of the Julian calendar in

      * 45 B.C., the leap years did not regularize until 8 A.D. This method ignores these

      * quirks, and pays attention only to the Julian onset date and the Gregorian

      * cutover (which can be changed).

      *

      * @param year  The given year.

      * @return      True if the given year is a leap year; false otherwise.

      * @stable ICU 2.0

      */

     UBool isLeapYear(int32_t year) const;

     /**

      * Returns TRUE if the given Calendar object is equivalent to this

      * one.  Calendar override.

      *

      * @param other the Calendar to be compared with this Calendar   

      * @stable ICU 2.4

      */

     virtual UBool isEquivalentTo(const Calendar& other) const;

     /**

      * (Overrides Calendar) Rolls up or down by the given amount in the specified field.

      * For more information, see the documentation for Calendar::roll().

      *

      * @param field   The time field.

      * @param amount  Indicates amount to roll.

      * @param status  Output param set to success/failure code on exit. If any value

      *                previously set in the time field is invalid, this will be set to

      *                an error status.

      * @deprecated ICU 2.6. Use roll(UCalendarDateFields field, int32_t amount, UErrorCode& status) instead.

      */

     virtual void roll(EDateFields field, int32_t amount, UErrorCode& status);

     /**

      * (Overrides Calendar) Rolls up or down by the given amount in the specified field.

      * For more information, see the documentation for Calendar::roll().

      *

      * @param field   The time field.

      * @param amount  Indicates amount to roll.

      * @param status  Output param set to success/failure code on exit. If any value

      *                previously set in the time field is invalid, this will be set to

      *                an error status.

      * @stable ICU 2.6.

      */

     virtual void roll(UCalendarDateFields field, int32_t amount, UErrorCode& status);

 #ifndef U_HIDE_DEPRECATED_API

     /**

      * Return the minimum value that this field could have, given the current date.

      * For the Gregorian calendar, this is the same as getMinimum() and getGreatestMinimum().

      * @param field    the time field.

      * @return         the minimum value that this field could have, given the current date.

      * @deprecated ICU 2.6. Use getActualMinimum(UCalendarDateFields field) instead.

      */

     int32_t getActualMinimum(EDateFields field) const;

     /**

      * Return the minimum value that this field could have, given the current date.

      * For the Gregorian calendar, this is the same as getMinimum() and getGreatestMinimum().

      * @param field    the time field.

      * @param status

      * @return         the minimum value that this field could have, given the current date.

      * @deprecated ICU 2.6. Use getActualMinimum(UCalendarDateFields field) instead. (Added to ICU 3.0 for signature consistency)

      */

     int32_t getActualMinimum(EDateFields field, UErrorCode& status) const;

 #endif  /* U_HIDE_DEPRECATED_API */

     /**

      * Return the minimum value that this field could have, given the current date.

      * For the Gregorian calendar, this is the same as getMinimum() and getGreatestMinimum().

      * @param field    the time field.

      * @param status   error result.

      * @return         the minimum value that this field could have, given the current date.

      * @stable ICU 3.0

      */

     int32_t getActualMinimum(UCalendarDateFields field, UErrorCode &status) const;

 #ifndef U_HIDE_DEPRECATED_API

     /**

      * Return the maximum value that this field could have, given the current date.

      * For example, with the date "Feb 3, 1997" and the DAY_OF_MONTH field, the actual

      * maximum would be 28; for "Feb 3, 1996" it s 29.  Similarly for a Hebrew calendar,

      * for some years the actual maximum for MONTH is 12, and for others 13.

      * @param field    the time field.

      * @return         the maximum value that this field could have, given the current date.

      * @deprecated ICU 2.6. Use getActualMaximum(UCalendarDateFields field) instead.

      */

     int32_t getActualMaximum(EDateFields field) const;

 #endif  /* U_HIDE_DEPRECATED_API */

     /**

      * Return the maximum value that this field could have, given the current date.

      * For example, with the date "Feb 3, 1997" and the DAY_OF_MONTH field, the actual

      * maximum would be 28; for "Feb 3, 1996" it s 29.  Similarly for a Hebrew calendar,

      * for some years the actual maximum for MONTH is 12, and for others 13.

      * @param field    the time field.

      * @param status   returns any errors that may result from this function call.

      * @return         the maximum value that this field could have, given the current date.

      * @stable ICU 2.6

      */

     virtual int32_t getActualMaximum(UCalendarDateFields field, UErrorCode& status) const;

     /**

      * (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.

      * @stable ICU 2.0

      */

     virtual UBool inDaylightTime(UErrorCode& status) const;

 public:

     /**

      * Override Calendar Returns a unique class ID POLYMORPHICALLY. Pure virtual

      * override. This method is to implement a simple version of RTTI, since not all C++

      * compilers support genuine RTTI. Polymorphic operator==() and clone() methods call

      * this method.

      *

      * @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.

      * @stable ICU 2.0

      */

     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.

      * @stable ICU 2.0

      */

     static UClassID U_EXPORT2 getStaticClassID(void);

     /**

      * Returns the calendar type name string for this Calendar object.

      * The returned string is the legacy ICU calendar attribute value,

      * for example, "gregorian" or "japanese".

      *

      * For more details see the Calendar::getType() documentation.

      *

      * @return legacy calendar type name string

      * @stable ICU 49

      */

     virtual const char * getType() const;

  private:

     GregorianCalendar(); // default constructor not implemented

  protected:

     /**

      * Return the ERA.  We need a special method for this because the

      * default ERA is AD, but a zero (unset) ERA is BC.

      * @return    the ERA.

      * @internal

      */

     virtual int32_t internalGetEra() const;

     /**

      * Return the Julian day number of day before the first day of the

      * given month in the given extended year.  Subclasses should override

      * this method to implement their calendar system.

      * @param eyear the extended year

      * @param month the zero-based month, or 0 if useMonth is false

      * @param useMonth if false, compute the day before the first day of

      * the given year, otherwise, compute the day before the first day of

      * the given month

      * @return the Julian day number of the day before the first

      * day of the given month and year

      * @internal

      */

     virtual int32_t handleComputeMonthStart(int32_t eyear, int32_t month,

                                                    UBool useMonth) const;

     /**

      * Subclasses may override this.  This method calls

      * handleGetMonthLength() to obtain the calendar-specific month

      * length.

      * @param bestField which field to use to calculate the date 

      * @return julian day specified by calendar fields.

      * @internal

      */

     virtual int32_t handleComputeJulianDay(UCalendarDateFields bestField)  ;

     /**

      * Return the number of days in the given month of the given extended

      * year of this calendar system.  Subclasses should override this

      * method if they can provide a more correct or more efficient

      * implementation than the default implementation in Calendar.

      * @internal

      */

     virtual int32_t handleGetMonthLength(int32_t extendedYear, int32_t month) const;

     /**

      * Return the number of days in the given extended year of this

      * calendar system.  Subclasses should override this method if they can

      * provide a more correct or more efficient implementation than the

      * default implementation in Calendar.

      * @stable ICU 2.0

      */

     virtual int32_t handleGetYearLength(int32_t eyear) const;

     /**

      * return the length of the given month.

      * @param month    the given month.

      * @return    the length of the given month.

      * @internal

      */

     virtual int32_t monthLength(int32_t month) const;

     /**

      * return the length of the month according to the given year.

      * @param month    the given month.

      * @param year     the given year.

      * @return         the length of the month

      * @internal

      */

     virtual int32_t monthLength(int32_t month, int32_t year) const;

 #ifndef U_HIDE_INTERNAL_API

     /**

      * return the length of the given year.

      * @param year    the given year.

      * @return        the length of the given year.

      * @internal

      */

     int32_t yearLength(int32_t year) const;

     /**

      * return the length of the year field.

      * @return    the length of the year field

      * @internal

      */

     int32_t yearLength(void) const;

     /**

      * After adjustments such as add(MONTH), add(YEAR), we don't want the

      * month to jump around.  E.g., we don't want Jan 31 + 1 month to go to Mar

      * 3, we want it to go to Feb 28.  Adjustments which might run into this

      * problem call this method to retain the proper month.

      * @internal

      */

     void pinDayOfMonth(void);

 #endif  /* U_HIDE_INTERNAL_API */

     /**

      * Return the day number with respect to the epoch.  January 1, 1970 (Gregorian)

      * is day zero.

      * @param status Fill-in parameter which receives the status of this operation.

      * @return       the day number with respect to the epoch.  

      * @internal

      */

     virtual UDate getEpochDay(UErrorCode& status);

     /**

      * Subclass API for defining limits of different types.

      * Subclasses must implement this method to return limits for the

      * following fields:

      *

      * <pre>UCAL_ERA

      * UCAL_YEAR

      * UCAL_MONTH

      * UCAL_WEEK_OF_YEAR

      * UCAL_WEEK_OF_MONTH

      * UCAL_DATE (DAY_OF_MONTH on Java)

      * UCAL_DAY_OF_YEAR

      * UCAL_DAY_OF_WEEK_IN_MONTH

      * UCAL_YEAR_WOY

      * UCAL_EXTENDED_YEAR</pre>

      *

      * @param field one of the above field numbers

      * @param limitType one of <code>MINIMUM</code>, <code>GREATEST_MINIMUM</code>,

      * <code>LEAST_MAXIMUM</code>, or <code>MAXIMUM</code>

      * @internal

      */

     virtual int32_t handleGetLimit(UCalendarDateFields field, ELimitType limitType) const;

     /**

      * Return the extended year defined by the current fields.  This will

      * use the UCAL_EXTENDED_YEAR field or the UCAL_YEAR and supra-year fields (such

      * as UCAL_ERA) specific to the calendar system, depending on which set of

      * fields is newer.

      * @return the extended year

      * @internal

      */

     virtual int32_t handleGetExtendedYear();

     /** 

      * Subclasses may override this to convert from week fields 

      * (YEAR_WOY and WEEK_OF_YEAR) to an extended year in the case

      * where YEAR, EXTENDED_YEAR are not set.

      * The Gregorian implementation assumes a yearWoy in gregorian format, according to the current era.

      * @return the extended year, UCAL_EXTENDED_YEAR

      * @internal

      */

     virtual int32_t handleGetExtendedYearFromWeekFields(int32_t yearWoy, int32_t woy);

     /**

      * Subclasses may override this method to compute several fields

      * specific to each calendar system.  These are:

      *

      * <ul><li>ERA

      * <li>YEAR

      * <li>MONTH

      * <li>DAY_OF_MONTH

      * <li>DAY_OF_YEAR

      * <li>EXTENDED_YEAR</ul>

      *

      * <p>The GregorianCalendar implementation implements

      * a calendar with the specified Julian/Gregorian cutover date.

      * @internal

      */

     virtual void handleComputeFields(int32_t julianDay, UErrorCode &status);

  private:

     /**

      * Compute the julian day number of the given year.

      * @param isGregorian    if true, using Gregorian calendar, otherwise using Julian calendar

      * @param year           the given year.

      * @param isLeap         true if the year is a leap year.       

      * @return 

      */

     static double computeJulianDayOfYear(UBool isGregorian, int32_t year,

                                          UBool& isLeap);

     /**

      * Validates the values of the set time fields.  True if they're all valid.

      * @return    True if the set time fields are all valid.

      */

     UBool validateFields(void) const;

     /**

      * Validates the value of the given time field.  True if it's valid.

      */

     UBool boundsCheck(int32_t value, UCalendarDateFields field) const;

     /**

      * Return the pseudo-time-stamp for two fields, given their

      * individual pseudo-time-stamps.  If either of the fields

      * is unset, then the aggregate is unset.  Otherwise, the

      * aggregate is the later of the two stamps.

      * @param stamp_a    One given field.

      * @param stamp_b    Another given field.

      * @return the pseudo-time-stamp for two fields

      */

     int32_t aggregateStamp(int32_t stamp_a, int32_t stamp_b);

     /**

      * The point at which the Gregorian calendar rules are used, measured in

      * milliseconds from the standard epoch.  Default is October 15, 1582

      * (Gregorian) 00:00:00 UTC, that is, October 4, 1582 (Julian) is followed

      * by October 15, 1582 (Gregorian).  This corresponds to Julian day number

      * 2299161. This is measured from the standard epoch, not in Julian Days.

      */

     UDate                fGregorianCutover;

     /**

      * Julian day number of the Gregorian cutover

      */

     int32_t             fCutoverJulianDay;

     /**

      * Midnight, local time (using this Calendar's TimeZone) at or before the

      * gregorianCutover. This is a pure date value with no time of day or

      * timezone component.

      */

     UDate                 fNormalizedGregorianCutover;// = gregorianCutover;

     /**

      * The year of the gregorianCutover, with 0 representing

      * 1 BC, -1 representing 2 BC, etc.

      */

     int32_t fGregorianCutoverYear;// = 1582;

     /**

      * The year of the gregorianCutover, with 0 representing

      * 1 BC, -1 representing 2 BC, etc.

      */

     int32_t fGregorianCutoverJulianDay;// = 2299161;

     /**

      * Converts time as milliseconds to Julian date. The Julian date used here is not a

      * true Julian date, since it is measured from midnight, not noon.

      *

      * @param millis  The given milliseconds.

      * @return        The Julian date number.

      */

     static double millisToJulianDay(UDate millis);

     /**

      * Converts Julian date to time as milliseconds. The Julian date used here is not a

      * true Julian date, since it is measured from midnight, not noon.

      *

      * @param julian  The given Julian date number.

      * @return        Time as milliseconds.

      */

     static UDate julianDayToMillis(double julian);

     /**

      * Used by handleComputeJulianDay() and handleComputeMonthStart().

      * Temporary field indicating whether the calendar is currently Gregorian as opposed to Julian.

      */

     UBool fIsGregorian;

     /**

      * Used by handleComputeJulianDay() and handleComputeMonthStart().

      * Temporary field indicating that the sense of the gregorian cutover should be inverted

      * to handle certain calculations on and around the cutover date.

      */

     UBool fInvertGregorian;

  public: // internal implementation

     /**

      * @return TRUE if this calendar has the notion of a default century

      * @internal 

      */

     virtual UBool haveDefaultCentury() const;

     /**

      * @return the start of the default century

      * @internal

      */

     virtual UDate defaultCenturyStart() const;

     /**

      * @return the beginning year of the default century

      * @internal 

      */

     virtual int32_t defaultCenturyStartYear() const;

 };

 U_NAMESPACE_END

 #endif /* #if !UCONFIG_NO_FORMATTING */

 #endif // _GREGOCAL

 //eof