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calendar.h (113121B)

---

// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
********************************************************************************
*   Copyright (C) 1997-2014, International Business Machines
*   Corporation and others.  All Rights Reserved.
********************************************************************************
*
* File CALENDAR.H
*
* Modification History:
*
*   Date        Name        Description
*   04/22/97    aliu        Expanded and corrected comments and other header
*                           contents.
*   05/01/97    aliu        Made equals(), before(), after() arguments const.
*   05/20/97    aliu        Replaced fAreFieldsSet with fAreFieldsInSync and
*                           fAreAllFieldsSet.
*   07/27/98    stephen     Sync up with JDK 1.2
*   11/15/99    weiv        added YEAR_WOY and DOW_LOCAL
*                           to EDateFields
*    8/19/2002  srl         Removed Javaisms
*   11/07/2003  srl         Update, clean up documentation.
********************************************************************************
*/

#ifndef CALENDAR_H
#define CALENDAR_H

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

/**
* \file
* \brief C++ API: Calendar object
*/
#if !UCONFIG_NO_FORMATTING

#include "unicode/uobject.h"
#include "unicode/locid.h"
#include "unicode/timezone.h"
#include "unicode/ucal.h"
#include "unicode/umisc.h"

U_NAMESPACE_BEGIN

class ICUServiceFactory;

// Do not conditionalize the following with #ifndef U_HIDE_INTERNAL_API,
// it is a return type for a virtual method (@internal)
/**
* @internal
*/
typedef int32_t UFieldResolutionTable[12][8];

class BasicTimeZone;
/**
* `Calendar` is an abstract base class for converting between
* a `UDate` object and a set of integer fields such as
* `YEAR`, `MONTH`, `DAY`, `HOUR`, and so on.
* (A `UDate` object represents a specific instant in
* time with millisecond precision. See UDate
* for information about the `UDate` class.)
*
* Subclasses of `Calendar` interpret a `UDate`
* according to the rules of a specific calendar system.
* The most commonly used subclass of `Calendar` is
* `GregorianCalendar`. Other subclasses could represent
* the various types of lunar calendars in use in many parts of the world.
*
* **NOTE**: (ICU 2.6) The subclass interface should be considered unstable -
* it WILL change.
*
* Like other locale-sensitive classes, `Calendar` provides a
* static method, `createInstance`, for getting a generally useful
* object of this type. `Calendar`'s `createInstance` method
* returns the appropriate `Calendar` subclass whose
* time fields have been initialized with the current date and time:
*
*     Calendar *rightNow = Calendar::createInstance(errCode);
*
* A `Calendar` object can produce all the time field values
* needed to implement the date-time formatting for a particular language
* and calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
*
* When computing a `UDate` from time fields, some special circumstances
* may arise: there may be insufficient information to compute the
* `UDate` (such as only year and month but no day in the month),
* there may be inconsistent information (such as "Tuesday, July 15, 1996"
* -- July 15, 1996 is actually a Monday), or the input time might be ambiguous
* because of time zone transition.
*
* **Insufficient information.** The calendar will use default
* information to specify the missing fields. This may vary by calendar; for
* the Gregorian calendar, the default for a field is the same as that of the
* start of the epoch: i.e., YEAR = 1970, MONTH = JANUARY, DATE = 1, etc.
*
* **Inconsistent information.** If fields conflict, the calendar
* will give preference to fields set more recently. For example, when
* determining the day, the calendar will look for one of the following
* combinations of fields.  The most recent combination, as determined by the
* most recently set single field, will be used.
*
*     MONTH + DAY_OF_MONTH
*     MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
*     MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
*     DAY_OF_YEAR
*     DAY_OF_WEEK + WEEK_OF_YEAR
*
* For the time of day:
*
*     HOUR_OF_DAY
*     AM_PM + HOUR
*
* **Ambiguous Wall Clock Time.** When time offset from UTC has
* changed, it produces an ambiguous time slot around the transition. For example,
* many US locations observe daylight saving time. On the date switching to daylight
* saving time in US, wall clock time jumps from 12:59 AM (standard) to 2:00 AM
* (daylight). Therefore, wall clock time from 1:00 AM to 1:59 AM do not exist on
* the date. When the input wall time fall into this missing time slot, the ICU
* Calendar resolves the time using the UTC offset before the transition by default.
* In this example, 1:30 AM is interpreted as 1:30 AM standard time (non-exist),
* so the final result will be 2:30 AM daylight time.
*
* On the date switching back to standard time, wall clock time is moved back one
* hour at 2:00 AM. So wall clock time from 1:00 AM to 1:59 AM occur twice. In this
* case, the ICU Calendar resolves the time using the UTC offset after the transition
* by default. For example, 1:30 AM on the date is resolved as 1:30 AM standard time.
*
* Ambiguous wall clock time resolution behaviors can be customized by Calendar APIs
* {@link #setRepeatedWallTimeOption} and {@link #setSkippedWallTimeOption}.
* These methods are available in ICU 49 or later versions.
*
* **Note:** for some non-Gregorian calendars, different
* fields may be necessary for complete disambiguation. For example, a full
* specification of the historical Arabic astronomical calendar requires year,
* month, day-of-month *and* day-of-week in some cases.
*
* **Note:** There are certain possible ambiguities in
* interpretation of certain singular times, which are resolved in the
* following ways:
*
*   1. 24:00:00 "belongs" to the following day. That is,
*      23:59 on Dec 31, 1969 < 24:00 on Jan 1, 1970 < 24:01:00 on Jan 1, 1970
*   2. Although historically not precise, midnight also belongs to "am",
*      and noon belongs to "pm", so on the same day,
*      12:00 am (midnight) < 12:01 am, and 12:00 pm (noon) < 12:01 pm
*
* The date or time format strings are not part of the definition of a
* calendar, as those must be modifiable or overridable by the user at
* runtime. Use `DateFormat` to format dates.
*
* `Calendar` provides an API for field "rolling", where fields
* can be incremented or decremented, but wrap around. For example, rolling the
* month up in the date December 12, **1996** results in
* January 12, **1996**.
*
* `Calendar` also provides a date arithmetic function for
* adding the specified (signed) amount of time to a particular time field.
* For example, subtracting 5 days from the date `September 12, 1996`
* results in `September 7, 1996`.
*
* ***Supported range***
*
* The allowable range of `Calendar` has been narrowed. `GregorianCalendar` used
* to attempt to support the range of dates with millisecond values from
* `Long.MIN_VALUE` to `Long.MAX_VALUE`. The new `Calendar` protocol specifies the
* maximum range of supportable dates as those having Julian day numbers
* of `-0x7F000000` to `+0x7F000000`. This corresponds to years from ~5,800,000 BCE
* to ~5,800,000 CE. Programmers should use the protected constants in `Calendar` to
* specify an extremely early or extremely late date.
*
* <p>
* The Japanese calendar uses a combination of era name and year number.
* When an emperor of Japan abdicates and a new emperor ascends the throne,
* a new era is declared and year number is reset to 1. Even if the date of
* abdication is scheduled ahead of time, the new era name might not be
* announced until just before the date. In such case, ICU4C may include
* a start date of future era without actual era name, but not enabled
* by default. ICU4C users who want to test the behavior of the future era
* can enable the tentative era by:
* <ul>
* <li>Environment variable <code>ICU_ENABLE_TENTATIVE_ERA=true</code>.</li>
* </ul>
*
* @stable ICU 2.0
*/
class U_I18N_API_CLASS Calendar : public UObject {
public:
#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Field IDs for date and time. Used to specify date/time fields. ERA is calendar
    * specific. Example ranges given are for illustration only; see specific Calendar
    * subclasses for actual ranges.
    * @deprecated ICU 2.6. Use C enum UCalendarDateFields defined in ucal.h
    */
   enum EDateFields {
#ifndef U_HIDE_DEPRECATED_API
/*
* ERA may be defined on other platforms. To avoid any potential problems undefined it here.
*/
#ifdef ERA
#undef ERA
#endif
       ERA,                  // Example: 0..1
       YEAR,                 // Example: 1..big number
       MONTH,                // Example: 0..11
       WEEK_OF_YEAR,         // Example: 1..53
       WEEK_OF_MONTH,        // Example: 1..4
       DATE,                 // Example: 1..31
       DAY_OF_YEAR,          // Example: 1..365
       DAY_OF_WEEK,          // Example: 1..7
       DAY_OF_WEEK_IN_MONTH, // Example: 1..4, may be specified as -1
       AM_PM,                // Example: 0..1
       HOUR,                 // Example: 0..11
       HOUR_OF_DAY,          // Example: 0..23
       MINUTE,               // Example: 0..59
       SECOND,               // Example: 0..59
       MILLISECOND,          // Example: 0..999
       ZONE_OFFSET,          // Example: -12*U_MILLIS_PER_HOUR..12*U_MILLIS_PER_HOUR
       DST_OFFSET,           // Example: 0 or U_MILLIS_PER_HOUR
       YEAR_WOY,             // 'Y' Example: 1..big number - Year of Week of Year
       DOW_LOCAL,            // 'e' Example: 1..7 - Day of Week / Localized

       EXTENDED_YEAR,
       JULIAN_DAY,
       MILLISECONDS_IN_DAY,
       IS_LEAP_MONTH,

       FIELD_COUNT = UCAL_FIELD_COUNT // See ucal.h for other fields.
#endif /* U_HIDE_DEPRECATED_API */
   };
#endif  // U_FORCE_HIDE_DEPRECATED_API

#ifndef U_HIDE_DEPRECATED_API
   /**
    * Useful constant for days of week. Note: Calendar day-of-week is 1-based. Clients
    * who create locale resources for the field of first-day-of-week should be aware of
    * this. For instance, in US locale, first-day-of-week is set to 1, i.e., SUNDAY.
    * @deprecated ICU 2.6. Use C enum UCalendarDaysOfWeek defined in ucal.h
    */
   enum EDaysOfWeek {
       SUNDAY = 1,
       MONDAY,
       TUESDAY,
       WEDNESDAY,
       THURSDAY,
       FRIDAY,
       SATURDAY
   };

   /**
    * Useful constants for month. Note: Calendar month is 0-based.
    * @deprecated ICU 2.6. Use C enum UCalendarMonths defined in ucal.h
    */
   enum EMonths {
       JANUARY,
       FEBRUARY,
       MARCH,
       APRIL,
       MAY,
       JUNE,
       JULY,
       AUGUST,
       SEPTEMBER,
       OCTOBER,
       NOVEMBER,
       DECEMBER,
       UNDECIMBER
   };

   /**
    * Useful constants for hour in 12-hour clock. Used in GregorianCalendar.
    * @deprecated ICU 2.6. Use C enum UCalendarAMPMs defined in ucal.h
    */
   enum EAmpm {
       AM,
       PM
   };
#endif  /* U_HIDE_DEPRECATED_API */

   /**
    * destructor
    * @stable ICU 2.0
    */
   U_I18N_API virtual ~Calendar();

   /**
    * Create and return a polymorphic copy of this calendar.
    *
    * @return    a polymorphic copy of this calendar.
    * @stable ICU 2.0
    */
   U_I18N_API virtual Calendar* clone() const = 0;

   /**
    * Creates a Calendar using the default timezone and locale. Clients are responsible
    * for deleting the object returned.
    *
    * @param success  Indicates the success/failure of Calendar creation. Filled in
    *                 with U_ZERO_ERROR if created successfully, set to a failure result
    *                 otherwise. U_MISSING_RESOURCE_ERROR will be returned if the resource data
    *                 requests a calendar type which has not been installed.
    * @return         A Calendar if created successfully. nullptr otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API static Calendar* U_EXPORT2 createInstance(UErrorCode& success);

   /**
    * Creates a Calendar using the given timezone and the default locale.
    * The Calendar takes ownership of zoneToAdopt; the
    * client must not delete it.
    *
    * @param zoneToAdopt  The given timezone to be adopted.
    * @param success      Indicates the success/failure of Calendar creation. Filled in
    *                     with U_ZERO_ERROR if created successfully, set to a failure result
    *                     otherwise.
    * @return             A Calendar if created successfully. nullptr otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API static Calendar* U_EXPORT2 createInstance(TimeZone* zoneToAdopt, UErrorCode& success);

   /**
    * Creates a Calendar using the given timezone and the default locale.  The TimeZone
    * is _not_ adopted; the client is still responsible for deleting it.
    *
    * @param zone  The timezone.
    * @param success      Indicates the success/failure of Calendar creation. Filled in
    *                     with U_ZERO_ERROR if created successfully, set to a failure result
    *                     otherwise.
    * @return             A Calendar if created successfully. nullptr otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API static Calendar* U_EXPORT2 createInstance(const TimeZone& zone, UErrorCode& success);

   /**
    * Creates a Calendar using the default timezone and the given locale.
    *
    * @param aLocale  The given locale.
    * @param success  Indicates the success/failure of Calendar creation. Filled in
    *                 with U_ZERO_ERROR if created successfully, set to a failure result
    *                 otherwise.
    * @return         A Calendar if created successfully. nullptr otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API static Calendar* U_EXPORT2 createInstance(const Locale& aLocale, UErrorCode& success);

   /**
    * Creates a Calendar using the given timezone and given locale.
    * The Calendar takes ownership of zoneToAdopt; the
    * client must not delete it.
    *
    * @param zoneToAdopt  The given timezone to be adopted.
    * @param aLocale      The given locale.
    * @param success      Indicates the success/failure of Calendar creation. Filled in
    *                     with U_ZERO_ERROR if created successfully, set to a failure result
    *                     otherwise.
    * @return             A Calendar if created successfully. nullptr otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API static Calendar* U_EXPORT2 createInstance(TimeZone* zoneToAdopt,
                                                        const Locale& aLocale,
                                                        UErrorCode& success);

   /**
    * Gets a Calendar using the given timezone and given locale.  The TimeZone
    * is _not_ adopted; the client is still responsible for deleting it.
    *
    * @param zone         The given timezone.
    * @param aLocale      The given locale.
    * @param success      Indicates the success/failure of Calendar creation. Filled in
    *                     with U_ZERO_ERROR if created successfully, set to a failure result
    *                     otherwise.
    * @return             A Calendar if created successfully. nullptr otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API static Calendar* U_EXPORT2 createInstance(const TimeZone& zone,
                                                        const Locale& aLocale,
                                                        UErrorCode& success);

   /**
    * Returns a list of the locales for which Calendars are installed.
    *
    * @param count  Number of locales returned.
    * @return       An array of Locale objects representing the set of locales for which
    *               Calendars are installed.  The system retains ownership of this list;
    *               the caller must NOT delete it. Does not include user-registered Calendars.
    * @stable ICU 2.0
    */
   U_I18N_API static const Locale* U_EXPORT2 getAvailableLocales(int32_t& count);

   /**
    * Given a key and a locale, returns an array of string values in a preferred
    * order that would make a difference. These are all and only those values where
    * the open (creation) of the service with the locale formed from the input locale
    * plus input keyword and that value has different behavior than creation with the
    * input locale alone.
    * @param key           one of the keys supported by this service.  For now, only
    *                      "calendar" is supported.
    * @param locale        the locale
    * @param commonlyUsed  if set to true it will return only commonly used values
    *                      with the given locale in preferred order.  Otherwise,
    *                      it will return all the available values for the locale.
    * @param status        ICU Error Code
    * @return a string enumeration over keyword values for the given key and the locale.
    * @stable ICU 4.2
    */
   U_I18N_API static StringEnumeration* U_EXPORT2 getKeywordValuesForLocale(const char* key,
                                                                            const Locale& locale,
                                                                            UBool commonlyUsed,
                                                                            UErrorCode& status);

   /**
    * Returns the current UTC (GMT) time measured in milliseconds since 0:00:00 on 1/1/70
    * (derived from the system time).
    *
    * @return   The current UTC time in milliseconds.
    * @stable ICU 2.0
    */
   U_I18N_API static UDate U_EXPORT2 getNow();

   /**
    * Gets this Calendar's time as milliseconds. May involve recalculation of time due
    * to previous calls to set time field values. The time specified is non-local UTC
    * (GMT) time. Although this method is const, this object may actually be changed
    * (semantically const).
    *
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @return        The current time in UTC (GMT) time, or zero if the operation
    *                failed.
    * @stable ICU 2.0
    */
   U_I18N_API inline UDate getTime(UErrorCode& status) const { return getTimeInMillis(status); }

   /**
    * Sets this Calendar's current time with the given UDate. The time specified should
    * be in non-local UTC (GMT) time.
    *
    * @param date  The given UDate in UTC (GMT) time.
    * @param status  Output param set to success/failure code on exit. If any value
    *                set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.0
    */
   U_I18N_API inline void setTime(UDate date, UErrorCode& status) { setTimeInMillis(date, status); }

   /**
    * Compares the equality of two Calendar objects. Objects of different subclasses
    * are considered unequal. This comparison is very exacting; two Calendar objects
    * must be in exactly the same state to be considered equal. To compare based on the
    * represented time, use equals() instead.
    *
    * @param that  The Calendar object to be compared with.
    * @return      true if the given Calendar is the same as this Calendar; false
    *              otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API virtual bool operator==(const Calendar& that) const;

   /**
    * Compares the inequality of two Calendar objects.
    *
    * @param that  The Calendar object to be compared with.
    * @return      true if the given Calendar is not the same as this Calendar; false
    *              otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API bool operator!=(const Calendar& that) const { return !operator==(that); }

   /**
    * Returns true if the given Calendar object is equivalent to this
    * one.  An equivalent Calendar will behave exactly as this one
    * does, but it may be set to a different time.  By contrast, for
    * the operator==() method to return true, the other Calendar must
    * be set to the same time.
    *
    * @param other the Calendar to be compared with this Calendar
    * @stable ICU 2.4
    */
   U_I18N_API virtual UBool isEquivalentTo(const Calendar& other) const;

   /**
    * Compares the Calendar time, whereas Calendar::operator== compares the equality of
    * Calendar objects.
    *
    * @param when    The Calendar to be compared with this Calendar. Although this is a
    *                const parameter, the object may be modified physically
    *                (semantically const).
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @return        True if the current time of this Calendar is equal to the time of
    *                Calendar when; false otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API UBool equals(const Calendar& when, UErrorCode& status) const;

   /**
    * Returns true if this Calendar's current time is before "when"'s current time.
    *
    * @param when    The Calendar to be compared with this Calendar. Although this is a
    *                const parameter, the object may be modified physically
    *                (semantically const).
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @return        True if the current time of this Calendar is before the time of
    *                Calendar when; false otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API UBool before(const Calendar& when, UErrorCode& status) const;

   /**
    * Returns true if this Calendar's current time is after "when"'s current time.
    *
    * @param when    The Calendar to be compared with this Calendar. Although this is a
    *                const parameter, the object may be modified physically
    *                (semantically const).
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @return        True if the current time of this Calendar is after the time of
    *                Calendar when; false otherwise.
    * @stable ICU 2.0
    */
   U_I18N_API UBool after(const Calendar& when, UErrorCode& status) const;

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * UDate Arithmetic function. Adds the specified (signed) amount of time to the given
    * time field, based on the calendar's rules. For example, to subtract 5 days from
    * the current time of the calendar, call add(Calendar::DATE, -5). When adding on
    * the month or Calendar::MONTH field, other fields like date might conflict and
    * need to be changed. For instance, adding 1 month on the date 01/31/96 will result
    * in 02/29/96.
    * Adding a positive value always means moving forward in time, so for the Gregorian calendar,
    * starting with 100 BC and adding +1 to year results in 99 BC (even though this actually reduces
    * the numeric value of the field itself).
    *
    * @param field   Specifies which date field to modify.
    * @param amount  The amount of time to be added to the field, in the natural unit
    *                for that field (e.g., days for the day fields, hours for the hour
    *                field.)
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @deprecated ICU 2.6. use add(UCalendarDateFields field, int32_t amount, UErrorCode& status) instead.
    */
   U_I18N_API virtual void add(EDateFields field, int32_t amount, UErrorCode& status);
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * UDate Arithmetic function. Adds the specified (signed) amount of time to the given
    * time field, based on the calendar's rules. For example, to subtract 5 days from
    * the current time of the calendar, call add(Calendar::DATE, -5). When adding on
    * the month or Calendar::MONTH field, other fields like date might conflict and
    * need to be changed. For instance, adding 1 month on the date 01/31/96 will result
    * in 02/29/96.
    * Adding a positive value always means moving forward in time, so for the Gregorian calendar,
    * starting with 100 BC and adding +1 to year results in 99 BC (even though this actually reduces
    * the numeric value of the field itself).
    *
    * @param field   Specifies which date field to modify.
    * @param amount  The amount of time to be added to the field, in the natural unit
    *                for that field (e.g., days for the day fields, hours for the hour
    *                field.)
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.6.
    */
   U_I18N_API virtual void add(UCalendarDateFields field, int32_t amount, UErrorCode& status);

#ifndef U_HIDE_DEPRECATED_API
   /**
    * Time Field Rolling function. Rolls (up/down) a single unit of time on the given
    * time field. For example, to roll the current date up by one day, call
    * roll(Calendar::DATE, true). When rolling on the year or Calendar::YEAR field, it
    * will roll the year value in the range between getMinimum(Calendar::YEAR) and the
    * value returned by getMaximum(Calendar::YEAR). When rolling on the month or
    * Calendar::MONTH field, other fields like date might conflict and, need to be
    * changed. For instance, rolling the month up on the date 01/31/96 will result in
    * 02/29/96. Rolling up always means rolling forward in time (unless the limit of the
    * field is reached, in which case it may pin or wrap), so for Gregorian calendar,
    * starting with 100 BC and rolling the year up results in 99 BC.
    * When eras have a definite beginning and end (as in the Chinese calendar, or as in
    * most eras in the Japanese calendar) then rolling the year past either limit of the
    * era will cause the year to wrap around. When eras only have a limit at one end,
    * then attempting to roll the year past that limit will result in pinning the year
    * at that limit. Note that for most calendars in which era 0 years move forward in
    * time (such as Buddhist, Hebrew, or Islamic), it is possible for add or roll to
    * result in negative years for era 0 (that is the only way to represent years before
    * the calendar epoch).
    * When rolling on the hour-in-day or Calendar::HOUR_OF_DAY field, it will roll the
    * hour value in the range between 0 and 23, which is zero-based.
    * <P>
    * NOTE: Do not use this method -- use roll(EDateFields, int, UErrorCode&) instead.
    *
    * @param field   The time field.
    * @param up      Indicates if the value of the specified time field is to be rolled
    *                up or rolled down. Use true if rolling up, false otherwise.
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @deprecated ICU 2.6. Use roll(UCalendarDateFields field, UBool up, UErrorCode& status) instead.
    */
   U_I18N_API inline void roll(EDateFields field, UBool up, UErrorCode& status);
#endif  /* U_HIDE_DEPRECATED_API */

   /**
    * Time Field Rolling function. Rolls (up/down) a single unit of time on the given
    * time field. For example, to roll the current date up by one day, call
    * roll(Calendar::DATE, true). When rolling on the year or Calendar::YEAR field, it
    * will roll the year value in the range between getMinimum(Calendar::YEAR) and the
    * value returned by getMaximum(Calendar::YEAR). When rolling on the month or
    * Calendar::MONTH field, other fields like date might conflict and, need to be
    * changed. For instance, rolling the month up on the date 01/31/96 will result in
    * 02/29/96. Rolling up always means rolling forward in time (unless the limit of the
    * field is reached, in which case it may pin or wrap), so for Gregorian calendar,
    * starting with 100 BC and rolling the year up results in 99 BC.
    * When eras have a definite beginning and end (as in the Chinese calendar, or as in
    * most eras in the Japanese calendar) then rolling the year past either limit of the
    * era will cause the year to wrap around. When eras only have a limit at one end,
    * then attempting to roll the year past that limit will result in pinning the year
    * at that limit. Note that for most calendars in which era 0 years move forward in
    * time (such as Buddhist, Hebrew, or Islamic), it is possible for add or roll to
    * result in negative years for era 0 (that is the only way to represent years before
    * the calendar epoch).
    * When rolling on the hour-in-day or Calendar::HOUR_OF_DAY field, it will roll the
    * hour value in the range between 0 and 23, which is zero-based.
    * <P>
    * NOTE: Do not use this method -- use roll(UCalendarDateFields, int, UErrorCode&) instead.
    *
    * @param field   The time field.
    * @param up      Indicates if the value of the specified time field is to be rolled
    *                up or rolled down. Use true if rolling up, false otherwise.
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.6.
    */
   U_I18N_API inline void roll(UCalendarDateFields field, UBool up, UErrorCode& status);

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Time Field Rolling function. Rolls by the given amount on the given
    * time field. For example, to roll the current date up by one day, call
    * roll(Calendar::DATE, +1, status). When rolling on the month or
    * Calendar::MONTH field, other fields like date might conflict and, need to be
    * changed. For instance, rolling the month up on the date 01/31/96 will result in
    * 02/29/96. Rolling by a positive value always means rolling forward in time (unless
    * the limit of the field is reached, in which case it may pin or wrap), so for
    * Gregorian calendar, starting with 100 BC and rolling the year by + 1 results in 99 BC.
    * When eras have a definite beginning and end (as in the Chinese calendar, or as in
    * most eras in the Japanese calendar) then rolling the year past either limit of the
    * era will cause the year to wrap around. When eras only have a limit at one end,
    * then attempting to roll the year past that limit will result in pinning the year
    * at that limit. Note that for most calendars in which era 0 years move forward in
    * time (such as Buddhist, Hebrew, or Islamic), it is possible for add or roll to
    * result in negative years for era 0 (that is the only way to represent years before
    * the calendar epoch).
    * When rolling on the hour-in-day or Calendar::HOUR_OF_DAY field, it will roll the
    * hour value in the range between 0 and 23, which is zero-based.
    * <P>
    * The only difference between roll() and add() is that roll() does not change
    * the value of more significant fields when it reaches the minimum or maximum
    * of its range, whereas add() does.
    *
    * @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.
    */
   U_I18N_API virtual void roll(EDateFields field, int32_t amount, UErrorCode& status);
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * Time Field Rolling function. Rolls by the given amount on the given
    * time field. For example, to roll the current date up by one day, call
    * roll(Calendar::DATE, +1, status). When rolling on the month or
    * Calendar::MONTH field, other fields like date might conflict and, need to be
    * changed. For instance, rolling the month up on the date 01/31/96 will result in
    * 02/29/96. Rolling by a positive value always means rolling forward in time (unless
    * the limit of the field is reached, in which case it may pin or wrap), so for
    * Gregorian calendar, starting with 100 BC and rolling the year by + 1 results in 99 BC.
    * When eras have a definite beginning and end (as in the Chinese calendar, or as in
    * most eras in the Japanese calendar) then rolling the year past either limit of the
    * era will cause the year to wrap around. When eras only have a limit at one end,
    * then attempting to roll the year past that limit will result in pinning the year
    * at that limit. Note that for most calendars in which era 0 years move forward in
    * time (such as Buddhist, Hebrew, or Islamic), it is possible for add or roll to
    * result in negative years for era 0 (that is the only way to represent years before
    * the calendar epoch).
    * When rolling on the hour-in-day or Calendar::HOUR_OF_DAY field, it will roll the
    * hour value in the range between 0 and 23, which is zero-based.
    * <P>
    * The only difference between roll() and add() is that roll() does not change
    * the value of more significant fields when it reaches the minimum or maximum
    * of its range, whereas add() does.
    *
    * @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.
    */
   U_I18N_API virtual void roll(UCalendarDateFields field, int32_t amount, UErrorCode& status);

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Return the difference between the given time and the time this
    * calendar object is set to.  If this calendar is set
    * <em>before</em> the given time, the returned value will be
    * positive.  If this calendar is set <em>after</em> the given
    * time, the returned value will be negative.  The
    * <code>field</code> parameter specifies the units of the return
    * value.  For example, if <code>fieldDifference(when,
    * Calendar::MONTH)</code> returns 3, then this calendar is set to
    * 3 months before <code>when</code>, and possibly some addition
    * time less than one month.
    *
    * <p>As a side effect of this call, this calendar is advanced
    * toward <code>when</code> by the given amount.  That is, calling
    * this method has the side effect of calling <code>add(field,
    * n)</code>, where <code>n</code> is the return value.
    *
    * <p>Usage: To use this method, call it first with the largest
    * field of interest, then with progressively smaller fields.  For
    * example:
    *
    * <pre>
    * int y = cal->fieldDifference(when, Calendar::YEAR, err);
    * int m = cal->fieldDifference(when, Calendar::MONTH, err);
    * int d = cal->fieldDifference(when, Calendar::DATE, err);</pre>
    *
    * computes the difference between <code>cal</code> and
    * <code>when</code> in years, months, and days.
    *
    * <p>Note: <code>fieldDifference()</code> is
    * <em>asymmetrical</em>.  That is, in the following code:
    *
    * <pre>
    * cal->setTime(date1, err);
    * int m1 = cal->fieldDifference(date2, Calendar::MONTH, err);
    * int d1 = cal->fieldDifference(date2, Calendar::DATE, err);
    * cal->setTime(date2, err);
    * int m2 = cal->fieldDifference(date1, Calendar::MONTH, err);
    * int d2 = cal->fieldDifference(date1, Calendar::DATE, err);</pre>
    *
    * one might expect that <code>m1 == -m2 && d1 == -d2</code>.
    * However, this is not generally the case, because of
    * irregularities in the underlying calendar system (e.g., the
    * Gregorian calendar has a varying number of days per month).
    *
    * @param when the date to compare this calendar's time to
    * @param field the field in which to compute the result
    * @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.
    * @return the difference, either positive or negative, between
    * this calendar's time and <code>when</code>, in terms of
    * <code>field</code>.
    * @deprecated ICU 2.6. Use fieldDifference(UDate when, UCalendarDateFields field, UErrorCode& status).
    */
   U_I18N_API virtual int32_t fieldDifference(UDate when, EDateFields field, UErrorCode& status);
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * Return the difference between the given time and the time this
    * calendar object is set to.  If this calendar is set
    * <em>before</em> the given time, the returned value will be
    * positive.  If this calendar is set <em>after</em> the given
    * time, the returned value will be negative.  The
    * <code>field</code> parameter specifies the units of the return
    * value.  For example, if <code>fieldDifference(when,
    * Calendar::MONTH)</code> returns 3, then this calendar is set to
    * 3 months before <code>when</code>, and possibly some addition
    * time less than one month.
    *
    * <p>As a side effect of this call, this calendar is advanced
    * toward <code>when</code> by the given amount.  That is, calling
    * this method has the side effect of calling <code>add(field,
    * n)</code>, where <code>n</code> is the return value.
    *
    * <p>Usage: To use this method, call it first with the largest
    * field of interest, then with progressively smaller fields.  For
    * example:
    *
    * <pre>
    * int y = cal->fieldDifference(when, Calendar::YEAR, err);
    * int m = cal->fieldDifference(when, Calendar::MONTH, err);
    * int d = cal->fieldDifference(when, Calendar::DATE, err);</pre>
    *
    * computes the difference between <code>cal</code> and
    * <code>when</code> in years, months, and days.
    *
    * <p>Note: <code>fieldDifference()</code> is
    * <em>asymmetrical</em>.  That is, in the following code:
    *
    * <pre>
    * cal->setTime(date1, err);
    * int m1 = cal->fieldDifference(date2, Calendar::MONTH, err);
    * int d1 = cal->fieldDifference(date2, Calendar::DATE, err);
    * cal->setTime(date2, err);
    * int m2 = cal->fieldDifference(date1, Calendar::MONTH, err);
    * int d2 = cal->fieldDifference(date1, Calendar::DATE, err);</pre>
    *
    * one might expect that <code>m1 == -m2 && d1 == -d2</code>.
    * However, this is not generally the case, because of
    * irregularities in the underlying calendar system (e.g., the
    * Gregorian calendar has a varying number of days per month).
    *
    * @param when the date to compare this calendar's time to
    * @param field the field in which to compute the result
    * @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.
    * @return the difference, either positive or negative, between
    * this calendar's time and <code>when</code>, in terms of
    * <code>field</code>.
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t fieldDifference(UDate when,
                                              UCalendarDateFields field,
                                              UErrorCode& status);

   /**
    * Sets the calendar's time zone to be the one passed in. The Calendar takes ownership
    * of the TimeZone; the caller is no longer responsible for deleting it.  If the
    * given time zone is nullptr, this function has no effect.
    *
    * @param value  The given time zone.
    * @stable ICU 2.0
    */
   U_I18N_API void adoptTimeZone(TimeZone* value);

   /**
    * Sets the calendar's time zone to be the same as the one passed in. The TimeZone
    * passed in is _not_ adopted; the client is still responsible for deleting it.
    *
    * @param zone  The given time zone.
    * @stable ICU 2.0
    */
   U_I18N_API void setTimeZone(const TimeZone& zone);

   /**
    * Returns a reference to the time zone owned by this calendar. The returned reference
    * is only valid until clients make another call to adoptTimeZone or setTimeZone,
    * or this Calendar is destroyed.
    *
    * @return   The time zone object associated with this calendar.
    * @stable ICU 2.0
    */
   U_I18N_API const TimeZone& getTimeZone() const;

   /**
    * Returns the time zone owned by this calendar. The caller owns the returned object
    * and must delete it when done.  After this call, the new time zone associated
    * with this Calendar is the default TimeZone as returned by TimeZone::createDefault().
    *
    * @return   The time zone object which was associated with this calendar.
    * @stable ICU 2.0
    */
   U_I18N_API TimeZone* orphanTimeZone();

   /**
    * Queries if the current date for this Calendar is in Daylight Savings Time.
    *
    * @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
    */
   U_I18N_API virtual UBool inDaylightTime(UErrorCode& status) const;

   /**
    * Specifies whether or not date/time interpretation is to be lenient. With lenient
    * interpretation, a date such as "February 942, 1996" will be treated as being
    * equivalent to the 941st day after February 1, 1996. With strict interpretation,
    * such dates will cause an error when computing time from the time field values
    * representing the dates.
    *
    * @param lenient  True specifies date/time interpretation to be lenient.
    *
    * @see            DateFormat#setLenient
    * @stable ICU 2.0
    */
   U_I18N_API void setLenient(UBool lenient);

   /**
    * Tells whether date/time interpretation is to be lenient.
    *
    * @return   True tells that date/time interpretation is to be lenient.
    * @stable ICU 2.0
    */
   U_I18N_API UBool isLenient() const;

   /**
    * Sets the behavior for handling wall time repeating multiple times
    * at negative time zone offset transitions. For example, 1:30 AM on
    * November 6, 2011 in US Eastern time (America/New_York) occurs twice;
    * 1:30 AM EDT, then 1:30 AM EST one hour later. When <code>UCAL_WALLTIME_FIRST</code>
    * is used, the wall time 1:30AM in this example will be interpreted as 1:30 AM EDT
    * (first occurrence). When <code>UCAL_WALLTIME_LAST</code> is used, it will be
    * interpreted as 1:30 AM EST (last occurrence). The default value is
    * <code>UCAL_WALLTIME_LAST</code>.
    * <p>
    * <b>Note:</b>When <code>UCAL_WALLTIME_NEXT_VALID</code> is not a valid
    * option for this. When the argument is neither <code>UCAL_WALLTIME_FIRST</code>
    * nor <code>UCAL_WALLTIME_LAST</code>, this method has no effect and will keep
    * the current setting.
    *
    * @param option the behavior for handling repeating wall time, either
    * <code>UCAL_WALLTIME_FIRST</code> or <code>UCAL_WALLTIME_LAST</code>.
    * @see #getRepeatedWallTimeOption
    * @stable ICU 49
    */
   U_I18N_API void setRepeatedWallTimeOption(UCalendarWallTimeOption option);

   /**
    * Gets the behavior for handling wall time repeating multiple times
    * at negative time zone offset transitions.
    *
    * @return the behavior for handling repeating wall time, either
    * <code>UCAL_WALLTIME_FIRST</code> or <code>UCAL_WALLTIME_LAST</code>.
    * @see #setRepeatedWallTimeOption
    * @stable ICU 49
    */
   U_I18N_API UCalendarWallTimeOption getRepeatedWallTimeOption() const;

   /**
    * Sets the behavior for handling skipped wall time at positive time zone offset
    * transitions. For example, 2:30 AM on March 13, 2011 in US Eastern time (America/New_York)
    * does not exist because the wall time jump from 1:59 AM EST to 3:00 AM EDT. When
    * <code>UCAL_WALLTIME_FIRST</code> is used, 2:30 AM is interpreted as 30 minutes before 3:00 AM
    * EDT, therefore, it will be resolved as 1:30 AM EST. When <code>UCAL_WALLTIME_LAST</code>
    * is used, 2:30 AM is interpreted as 31 minutes after 1:59 AM EST, therefore, it will be
    * resolved as 3:30 AM EDT. When <code>UCAL_WALLTIME_NEXT_VALID</code> is used, 2:30 AM will
    * be resolved as next valid wall time, that is 3:00 AM EDT. The default value is
    * <code>UCAL_WALLTIME_LAST</code>.
    * <p>
    * <b>Note:</b>This option is effective only when this calendar is lenient.
    * When the calendar is strict, such non-existing wall time will cause an error.
    *
    * @param option the behavior for handling skipped wall time at positive time zone
    * offset transitions, one of <code>UCAL_WALLTIME_FIRST</code>, <code>UCAL_WALLTIME_LAST</code> and
    * <code>UCAL_WALLTIME_NEXT_VALID</code>.
    * @see #getSkippedWallTimeOption
    *
    * @stable ICU 49
    */
   U_I18N_API void setSkippedWallTimeOption(UCalendarWallTimeOption option);

   /**
    * Gets the behavior for handling skipped wall time at positive time zone offset
    * transitions.
    *
    * @return the behavior for handling skipped wall time, one of
    * <code>UCAL_WALLTIME_FIRST</code>, <code>UCAL_WALLTIME_LAST</code>
    * and <code>UCAL_WALLTIME_NEXT_VALID</code>.
    * @see #setSkippedWallTimeOption
    * @stable ICU 49
    */
   U_I18N_API UCalendarWallTimeOption getSkippedWallTimeOption() const;

   /**
    * Sets what the first day of the week is; e.g., Sunday in US, Monday in France.
    *
    * @param value  The given first day of the week.
    * @stable ICU 2.6.
    */
   U_I18N_API void setFirstDayOfWeek(UCalendarDaysOfWeek value);

#ifndef U_HIDE_DEPRECATED_API
   /**
    * Gets what the first day of the week is; e.g., Sunday in US, Monday in France.
    *
    * @return   The first day of the week.
    * @deprecated ICU 2.6 use the overload with error code
    */
   U_I18N_API EDaysOfWeek getFirstDayOfWeek() const;
#endif  /* U_HIDE_DEPRECATED_API */

   /**
    * Gets what the first day of the week is; e.g., Sunday in US, Monday in France.
    *
    * @param status error code
    * @return   The first day of the week.
    * @stable ICU 2.6
    */
   U_I18N_API UCalendarDaysOfWeek getFirstDayOfWeek(UErrorCode& status) const;

   /**
    * Sets what the minimal days required in the first week of the year are; For
    * example, if the first week is defined as one that contains the first day of the
    * first month of a year, call the method with value 1. If it must be a full week,
    * use value 7.
    *
    * @param value  The given minimal days required in the first week of the year.
    * @stable ICU 2.0
    */
   U_I18N_API void setMinimalDaysInFirstWeek(uint8_t value);

   /**
    * Gets what the minimal days required in the first week of the year are; e.g., if
    * the first week is defined as one that contains the first day of the first month
    * of a year, getMinimalDaysInFirstWeek returns 1. If the minimal days required must
    * be a full week, getMinimalDaysInFirstWeek returns 7.
    *
    * @return   The minimal days required in the first week of the year.
    * @stable ICU 2.0
    */
   U_I18N_API uint8_t getMinimalDaysInFirstWeek() const;

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Gets the minimum value for the given time field. e.g., for Gregorian
    * DAY_OF_MONTH, 1.
    *
    * @param field  The given time field.
    * @return       The minimum value for the given time field.
    * @deprecated ICU 2.6. Use getMinimum(UCalendarDateFields field) instead.
    */
   U_I18N_API virtual int32_t getMinimum(EDateFields field) const;
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * Gets the minimum value for the given time field. e.g., for Gregorian
    * DAY_OF_MONTH, 1.
    *
    * @param field  The given time field.
    * @return       The minimum value for the given time field.
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t getMinimum(UCalendarDateFields field) const;

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Gets the maximum value for the given time field. e.g. for Gregorian DAY_OF_MONTH,
    * 31.
    *
    * @param field  The given time field.
    * @return       The maximum value for the given time field.
    * @deprecated ICU 2.6. Use getMaximum(UCalendarDateFields field) instead.
    */
   U_I18N_API virtual int32_t getMaximum(EDateFields field) const;
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * Gets the maximum value for the given time field. e.g. for Gregorian DAY_OF_MONTH,
    * 31.
    *
    * @param field  The given time field.
    * @return       The maximum value for the given time field.
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t getMaximum(UCalendarDateFields field) const;

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Gets the highest minimum value for the given field if varies. Otherwise same as
    * getMinimum(). For Gregorian, no difference.
    *
    * @param field  The given time field.
    * @return       The highest minimum value for the given time field.
    * @deprecated ICU 2.6. Use getGreatestMinimum(UCalendarDateFields field) instead.
    */
   U_I18N_API virtual int32_t getGreatestMinimum(EDateFields field) const;
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * Gets the highest minimum value for the given field if varies. Otherwise same as
    * getMinimum(). For Gregorian, no difference.
    *
    * @param field  The given time field.
    * @return       The highest minimum value for the given time field.
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t getGreatestMinimum(UCalendarDateFields field) const;

#ifndef U_FORCE_HIDE_DEPRECATED_API
   /**
    * Gets the lowest maximum value for the given field if varies. Otherwise same as
    * getMaximum(). e.g., for Gregorian DAY_OF_MONTH, 28.
    *
    * @param field  The given time field.
    * @return       The lowest maximum value for the given time field.
    * @deprecated ICU 2.6. Use getLeastMaximum(UCalendarDateFields field) instead.
    */
   U_I18N_API virtual int32_t getLeastMaximum(EDateFields field) const;
#endif  // U_FORCE_HIDE_DEPRECATED_API

   /**
    * Gets the lowest maximum value for the given field if varies. Otherwise same as
    * getMaximum(). e.g., for Gregorian DAY_OF_MONTH, 28.
    *
    * @param field  The given time field.
    * @return       The lowest maximum value for the given time field.
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t getLeastMaximum(UCalendarDateFields field) const;

#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().
    *
    * The version of this function on Calendar uses an iterative algorithm to determine the
    * actual minimum value for the field.  There is almost always a more efficient way to
    * accomplish this (in most cases, you can simply return getMinimum()).  GregorianCalendar
    * overrides this function with a more efficient implementation.
    *
    * @param field    the field to determine the minimum of
    * @param status   Fill-in parameter which receives the status of this operation.
    * @return         the minimum of the given field for the current date of this Calendar
    * @deprecated ICU 2.6. Use getActualMinimum(UCalendarDateFields field, UErrorCode& status) instead.
    */
   U_I18N_API 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().
    *
    * The version of this function on Calendar uses an iterative algorithm to determine the
    * actual minimum value for the field.  There is almost always a more efficient way to
    * accomplish this (in most cases, you can simply return getMinimum()).  GregorianCalendar
    * overrides this function with a more efficient implementation.
    *
    * @param field    the field to determine the minimum of
    * @param status   Fill-in parameter which receives the status of this operation.
    * @return         the minimum of the given field for the current date of this Calendar
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t getActualMinimum(UCalendarDateFields field, UErrorCode& status) const;

   /**
    * 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.
    *
    * The version of this function on Calendar uses an iterative algorithm to determine the
    * actual maximum value for the field.  There is almost always a more efficient way to
    * accomplish this (in most cases, you can simply return getMaximum()).  GregorianCalendar
    * overrides this function with a more efficient implementation.
    *
    * @param field    the field to determine the maximum of
    * @param status   Fill-in parameter which receives the status of this operation.
    * @return         the maximum of the given field for the current date of this Calendar
    * @stable ICU 2.6.
    */
   U_I18N_API virtual int32_t getActualMaximum(UCalendarDateFields field, UErrorCode& status) const;

   /**
    * Gets the value for a given time field. Recalculate the current time field values
    * if the time value has been changed by a call to setTime(). Return zero for unset
    * fields if any fields have been explicitly set by a call to set(). To force a
    * recomputation of all fields regardless of the previous state, call complete().
    * This method is semantically const, but may alter the object in memory.
    *
    * @param field  The given time field.
    * @param status Fill-in parameter which receives the status of the operation.
    * @return       The value for the given time field, or zero if the field is unset,
    *               and set() has been called for any other field.
    * @stable ICU 2.6.
    */
   U_I18N_API int32_t get(UCalendarDateFields field, UErrorCode& status) const;

   /**
    * Determines if the given time field has a value set. This can affect in the
    * resolving of time in Calendar. Unset fields have a value of zero, by definition.
    *
    * @param field  The given time field.
    * @return   True if the given time field has a value set; false otherwise.
    * @stable ICU 2.6.
    */
   U_I18N_API UBool isSet(UCalendarDateFields field) const;

   /**
    * Sets the given time field with the given value.
    *
    * @param field  The given time field.
    * @param value  The value to be set for the given time field.
    * @stable ICU 2.6.
    */
   U_I18N_API void set(UCalendarDateFields field, int32_t value);

   /**
    * Sets the values for the fields YEAR, MONTH, and DATE. Other field values are
    * retained; call clear() first if this is not desired.
    *
    * @param year   The value used to set the YEAR time field.
    * @param month  The value used to set the MONTH time field. Month value is 0-based.
    *               e.g., 0 for January.
    * @param date   The value used to set the DATE time field.
    * @stable ICU 2.0
    */
   U_I18N_API void set(int32_t year, int32_t month, int32_t date);

   /**
    * Sets the values for the fields YEAR, MONTH, DATE, HOUR_OF_DAY, and MINUTE. Other
    * field values are retained; call clear() first if this is not desired.
    *
    * @param year    The value used to set the YEAR time field.
    * @param month   The value used to set the MONTH time field. Month value is
    *                0-based. E.g., 0 for January.
    * @param date    The value used to set the DATE time field.
    * @param hour    The value used to set the HOUR_OF_DAY time field.
    * @param minute  The value used to set the MINUTE time field.
    * @stable ICU 2.0
    */
   U_I18N_API void set(int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute);

   /**
    * Sets the values for the fields YEAR, MONTH, DATE, HOUR_OF_DAY, MINUTE, and SECOND.
    * Other field values are retained; call clear() first if this is not desired.
    *
    * @param year    The value used to set the YEAR time field.
    * @param month   The value used to set the MONTH time field. Month value is
    *                0-based. E.g., 0 for January.
    * @param date    The value used to set the DATE time field.
    * @param hour    The value used to set the HOUR_OF_DAY time field.
    * @param minute  The value used to set the MINUTE time field.
    * @param second  The value used to set the SECOND time field.
    * @stable ICU 2.0
    */
   U_I18N_API void set(int32_t year, int32_t month, int32_t date,
                       int32_t hour, int32_t minute, int32_t second);

   /**
    * Clears the values of all the time fields, making them both unset and assigning
    * them a value of zero. The field values will be determined during the next
    * resolving of time into time fields.
    * @stable ICU 2.0
    */
   U_I18N_API void clear();

   /**
    * Clears the value in the given time field, both making it unset and assigning it a
    * value of zero. This field value will be determined during the next resolving of
    * time into time fields. Clearing UCAL_ORDINAL_MONTH or UCAL_MONTH will
    * clear both fields.
    *
    * @param field  The time field to be cleared.
    * @stable ICU 2.6.
    */
   U_I18N_API void clear(UCalendarDateFields field);

   /**
    * Returns a unique class ID POLYMORPHICALLY. Pure virtual method. 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.
    * <P>
    * Concrete subclasses of Calendar must implement getDynamicClassID() and also a
    * static method and data member:
    *
    *      static UClassID getStaticClassID() { return (UClassID)&amp;fgClassID; }
    *      static char fgClassID;
    *
    * @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
    */
   U_I18N_API virtual UClassID getDynamicClassID() const override = 0;

   /**
    * 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".
    *
    * See type="old type name" for the calendar attribute of locale IDs
    * at http://www.unicode.org/reports/tr35/#Key_Type_Definitions
    *
    * Sample code for getting the LDML/BCP 47 calendar key value:
    * \code
    * const char *calType = cal->getType();
    * if (0 == strcmp(calType, "unknown")) {
    *     // deal with unknown calendar type
    * } else {
    *     string localeID("root@calendar=");
    *     localeID.append(calType);
    *     char langTag[100];
    *     UErrorCode errorCode = U_ZERO_ERROR;
    *     int32_t length = uloc_toLanguageTag(localeID.c_str(), langTag, (int32_t)sizeof(langTag), true, &errorCode);
    *     if (U_FAILURE(errorCode)) {
    *         // deal with errors & overflow
    *     }
    *     string lang(langTag, length);
    *     size_t caPos = lang.find("-ca-");
    *     lang.erase(0, caPos + 4);
    *     // lang now contains the LDML calendar type
    * }
    * \endcode
    *
    * @return legacy calendar type name string
    * @stable ICU 49
    */
   U_I18N_API virtual const char* getType() const = 0;

   /**
    * Returns whether the given day of the week is a weekday, a weekend day,
    * or a day that transitions from one to the other, for the locale and
    * calendar system associated with this Calendar (the locale's region is
    * often the most determinant factor). If a transition occurs at midnight,
    * then the days before and after the transition will have the
    * type UCAL_WEEKDAY or UCAL_WEEKEND. If a transition occurs at a time
    * other than midnight, then the day of the transition will have
    * the type UCAL_WEEKEND_ONSET or UCAL_WEEKEND_CEASE. In this case, the
    * method getWeekendTransition() will return the point of
    * transition.
    * @param dayOfWeek The day of the week whose type is desired (UCAL_SUNDAY..UCAL_SATURDAY).
    * @param status The error code for the operation.
    * @return The UCalendarWeekdayType for the day of the week.
    * @stable ICU 4.4
    */
   U_I18N_API virtual UCalendarWeekdayType getDayOfWeekType(UCalendarDaysOfWeek dayOfWeek,
                                                            UErrorCode& status) const;

   /**
    * Returns the time during the day at which the weekend begins or ends in
    * this calendar system.  If getDayOfWeekType() returns UCAL_WEEKEND_ONSET
    * for the specified dayOfWeek, return the time at which the weekend begins.
    * If getDayOfWeekType() returns UCAL_WEEKEND_CEASE for the specified dayOfWeek,
    * return the time at which the weekend ends. If getDayOfWeekType() returns
    * some other UCalendarWeekdayType for the specified dayOfWeek, is it an error condition
    * (U_ILLEGAL_ARGUMENT_ERROR).
    * @param dayOfWeek The day of the week for which the weekend transition time is
    * desired (UCAL_SUNDAY..UCAL_SATURDAY).
    * @param status The error code for the operation.
    * @return The milliseconds after midnight at which the weekend begins or ends.
    * @stable ICU 4.4
    */
   U_I18N_API virtual int32_t getWeekendTransition(UCalendarDaysOfWeek dayOfWeek,
                                                   UErrorCode& status) const;

   /**
    * Returns true if the given UDate is in the weekend in
    * this calendar system.
    * @param date The UDate in question.
    * @param status The error code for the operation.
    * @return true if the given UDate is in the weekend in
    * this calendar system, false otherwise.
    * @stable ICU 4.4
    */
   U_I18N_API virtual UBool isWeekend(UDate date, UErrorCode& status) const;

   /**
    * Returns true if this Calendar's current date-time is in the weekend in
    * this calendar system.
    * @return true if this Calendar's current date-time is in the weekend in
    * this calendar system, false otherwise.
    * @stable ICU 4.4
    */
   U_I18N_API virtual UBool isWeekend() const;

   /**
    * Returns true if the date is in a leap year. Recalculate the current time
    * field values if the time value has been changed by a call to * setTime().
    * This method is semantically const, but may alter the object in memory.
    * A "leap year" is a year that contains more days than other years (for
    * solar or lunar calendars) or more months than other years (for lunisolar
    * calendars like Hebrew or Chinese), as defined in the ECMAScript Temporal
    * proposal.
    *
    * @param status        ICU Error Code
    * @return       True if the date in the fields is in a Temporal proposal
    *               defined leap year. False otherwise.
    * @stable ICU 73
    */
   U_I18N_API virtual bool inTemporalLeapYear(UErrorCode& status) const;

   /**
    * Gets The Temporal monthCode value corresponding to the month for the date.
    * The value is a string identifier that starts with the literal grapheme
    * "M" followed by two graphemes representing the zero-padded month number
    * of the current month in a normal (non-leap) year and suffixed by an
    * optional literal grapheme "L" if this is a leap month in a lunisolar
    * calendar. The 25 possible values are "M01" .. "M13" and "M01L" .. "M12L".
    * For the Hebrew calendar, the values are "M01" .. "M12" for non-leap year, and
    * "M01" .. "M05", "M05L", "M06" .. "M12" for leap year.
    * For the Chinese calendar, the values are "M01" .. "M12" for non-leap year and
    * in leap year with another monthCode in "M01L" .. "M12L".
    * For Coptic and Ethiopian calendar, the Temporal monthCode values for any
    * years are "M01" to "M13".
    *
    * @param status        ICU Error Code
    * @return       One of 25 possible strings in {"M01".."M13", "M01L".."M12L"}.
    * @stable ICU 73
    */
   U_I18N_API virtual const char* getTemporalMonthCode(UErrorCode& status) const;

   /**
    * Sets The Temporal monthCode which is a string identifier that starts
    * with the literal grapheme "M" followed by two graphemes representing
    * the zero-padded month number of the current month in a normal
    * (non-leap) year and suffixed by an optional literal grapheme "L" if this
    * is a leap month in a lunisolar calendar. The 25 possible values are
    * "M01" .. "M13" and "M01L" .. "M12L". For Hebrew calendar, the values are
    * "M01" .. "M12" for non-leap years, and "M01" .. "M05", "M05L", "M06"
    * .. "M12" for leap year.
    * For the Chinese calendar, the values are "M01" .. "M12" for non-leap year and
    * in leap year with another monthCode in "M01L" .. "M12L".
    * For Coptic and Ethiopian calendar, the Temporal monthCode values for any
    * years are "M01" to "M13".
    *
    * @param temporalMonth  The value to be set for temporal monthCode.
    * @param status        ICU Error Code
    *
    * @stable ICU 73
    */
   U_I18N_API virtual void setTemporalMonthCode(const char* temporalMonth, UErrorCode& status);

protected:

    /**
     * Constructs a Calendar with the default time zone as returned by
     * TimeZone::createInstance(), and the default locale.
     *
     * @param success  Indicates the status of Calendar object construction. Returns
     *                 U_ZERO_ERROR if constructed successfully.
    * @stable ICU 2.0
     */
   U_I18N_API Calendar(UErrorCode& success);

   /**
    * Copy constructor
    *
    * @param source    Calendar object to be copied from
    * @stable ICU 2.0
    */
   U_I18N_API Calendar(const Calendar& source);

   /**
    * Default assignment operator
    *
    * @param right    Calendar object to be copied
    * @stable ICU 2.0
    */
   U_I18N_API Calendar& operator=(const Calendar& right);

   /**
    * Constructs a Calendar with the given time zone and locale. Clients are no longer
    * responsible for deleting the given time zone object after it's adopted.
    *
    * @param zone     The given time zone.
    * @param aLocale  The given locale.
    * @param success  Indicates the status of Calendar object construction. Returns
    *                 U_ZERO_ERROR if constructed successfully.
    * @stable ICU 2.0
    */
   U_I18N_API Calendar(TimeZone* zone, const Locale& aLocale, UErrorCode& success);

   /**
    * Constructs a Calendar with the given time zone and locale.
    *
    * @param zone     The given time zone.
    * @param aLocale  The given locale.
    * @param success  Indicates the status of Calendar object construction. Returns
    *                 U_ZERO_ERROR if constructed successfully.
    * @stable ICU 2.0
    */
   U_I18N_API Calendar(const TimeZone& zone, const Locale& aLocale, UErrorCode& success);

   /**
    * Converts Calendar's time field values to GMT as milliseconds.
    *
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.0
    */
   U_I18N_API virtual void computeTime(UErrorCode& status);

   /**
    * Converts GMT as milliseconds to time field values. This allows you to sync up the
    * time field values with a new time that is set for the calendar.  This method
    * does NOT recompute the time first; to recompute the time, then the fields, use
    * the method complete().
    *
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.0
    */
   U_I18N_API virtual void computeFields(UErrorCode& status);

   /**
    * Gets this Calendar's current time as a long.
    *
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @return the current time as UTC milliseconds from the epoch.
    * @stable ICU 2.0
    */
   U_I18N_API double getTimeInMillis(UErrorCode& status) const;

   /**
    * Sets this Calendar's current time from the given long value.
    * @param millis  the new time in UTC milliseconds from the epoch.
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.0
    */
   U_I18N_API void setTimeInMillis(double millis, UErrorCode& status);

   /**
    * Recomputes the current time from currently set fields, and then fills in any
    * unset fields in the time field list.
    *
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    * @stable ICU 2.0
    */
   U_I18N_API void complete(UErrorCode& status);

#ifndef U_HIDE_DEPRECATED_API
   /**
    * Gets the value for a given time field. Subclasses can use this function to get
    * field values without forcing recomputation of time.
    *
    * @param field  The given time field.
    * @return       The value for the given time field.
    * @deprecated ICU 2.6. Use internalGet(UCalendarDateFields field) instead.
    */
   U_I18N_API inline int32_t internalGet(EDateFields field) const { return fFields[field]; }
#endif  /* U_HIDE_DEPRECATED_API */

#ifndef U_HIDE_INTERNAL_API
   /**
    * Gets the value for a given time field. Subclasses can use this function to get
    * field values without forcing recomputation of time. If the field's stamp is UNSET,
    * the defaultValue is used.
    *
    * @param field  The given time field.
    * @param defaultValue a default value used if the field is unset.
    * @return       The value for the given time field.
    * @internal
    */
   U_I18N_API inline int32_t internalGet(UCalendarDateFields field, int32_t defaultValue) const {
       return fStamp[field] > kUnset ? fFields[field] : defaultValue;
   }

   /**
    * Gets the value for a given time field. Subclasses can use this function to get
    * field values without forcing recomputation of time.
    *
    * @param field  The given time field.
    * @return       The value for the given time field.
    * @internal
    */
   U_I18N_API inline int32_t internalGet(UCalendarDateFields field) const { return fFields[field]; }

   /**
    * The year in this calendar is counting from 1 backward if the era is 0.
    * @return The year in era 0 of this calendar is counting backward from 1.
    * @internal
    */
   U_I18N_API virtual bool isEra0CountingBackward() const { return false; }

   /**
    * Related year difference.
    * @return The difference in Related year.
    * @internal
    */
   U_I18N_API virtual int32_t getRelatedYearDifference() const;

#endif  /* U_HIDE_INTERNAL_API */

   /**
    * Use this function instead of internalGet(UCAL_MONTH). The implementation
    * check the timestamp of UCAL_MONTH and UCAL_ORDINAL_MONTH and use the
    * one set later. The subclass should override it to conver the value of UCAL_ORDINAL_MONTH
    * to UCAL_MONTH correctly if UCAL_ORDINAL_MONTH has higher priority.
    *
    * @return       The value for the UCAL_MONTH.
    * @internal
    */
   U_I18N_API virtual int32_t internalGetMonth(UErrorCode& status) const;

   /**
    * Use this function instead of internalGet(UCAL_MONTH, defaultValue). The implementation
    * check the timestamp of UCAL_MONTH and UCAL_ORDINAL_MONTH and use the
    * one set later. The subclass should override it to conver the value of UCAL_ORDINAL_MONTH
    * to UCAL_MONTH correctly if UCAL_ORDINAL_MONTH has higher priority.
    *
    * @param defaultValue a default value used if the UCAL_MONTH and
    *   UCAL_ORDINAL are both unset.
    * @param status Output param set to failure code on function return
    *          when this function fails.
    * @return       The value for the UCAL_MONTH.
    * @internal
    */
   U_I18N_API virtual int32_t internalGetMonth(int32_t defaultValue, UErrorCode& status) const;

#ifndef U_HIDE_DEPRECATED_API
   /**
    * Sets the value for a given time field.  This is a fast internal method for
    * subclasses.  It does not affect the areFieldsInSync, isTimeSet, or areAllFieldsSet
    * flags.
    *
    * @param field    The given time field.
    * @param value    The value for the given time field.
    * @deprecated ICU 2.6. Use internalSet(UCalendarDateFields field, int32_t value) instead.
    */
   U_I18N_API void internalSet(EDateFields field, int32_t value);
#endif  /* U_HIDE_DEPRECATED_API */

   /**
    * Sets the value for a given time field.  This is a fast internal method for
    * subclasses.  It does not affect the areFieldsInSync, isTimeSet, or areAllFieldsSet
    * flags.
    *
    * @param field    The given time field.
    * @param value    The value for the given time field.
    * @stable ICU 2.6.
    */
   U_I18N_API inline void internalSet(UCalendarDateFields field, int32_t value);

   /**
    * Prepare this calendar for computing the actual minimum or maximum.
    * This method modifies this calendar's fields; it is called on a
    * temporary calendar.
    * @internal
    */
   U_I18N_API virtual void prepareGetActual(UCalendarDateFields field,
                                            UBool isMinimum,
                                            UErrorCode& status);

   /**
    * Limit enums. Not in sync with UCalendarLimitType (refers to internal fields).
    * @internal
    */
   enum ELimitType {
#ifndef U_HIDE_INTERNAL_API
     UCAL_LIMIT_MINIMUM = 0,
     UCAL_LIMIT_GREATEST_MINIMUM,
     UCAL_LIMIT_LEAST_MAXIMUM,
     UCAL_LIMIT_MAXIMUM,
     UCAL_LIMIT_COUNT
#endif  /* U_HIDE_INTERNAL_API */
   };

   /**
    * 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
    */
   U_I18N_API virtual int32_t handleGetLimit(UCalendarDateFields field, ELimitType limitType) const = 0;

   /**
    * Return a limit for a field.
    * @param field the field, from <code>0..UCAL_MAX_FIELD</code>
    * @param limitType the type specifier for the limit
    * @see #ELimitType
    * @internal
    */
   U_I18N_API virtual int32_t getLimit(UCalendarDateFields field, ELimitType limitType) 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
    * @param status Output param set to failure code on function return
    *          when this function fails.
    * @return the Julian day number of the day before the first
    * day of the given month and year
    * @internal
    */
   U_I18N_API virtual int64_t handleComputeMonthStart(int32_t eyear,
                                                      int32_t month,
                                                      UBool useMonth,
                                                      UErrorCode& status) const = 0;

   /**
    * 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
    */
   U_I18N_API virtual int32_t handleGetMonthLength(int32_t extendedYear,
                                                   int32_t month,
                                                   UErrorCode& status) 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.
    * @internal
    */
   U_I18N_API virtual int32_t handleGetYearLength(int32_t eyear, UErrorCode& status) 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.
    * @param status        ICU Error Code
    * @return the extended year
    * @internal
    */
   U_I18N_API virtual int32_t handleGetExtendedYear(UErrorCode& status) = 0;

   /**
    * 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
    * @param status        ICU Error Code
    * @return julian day specified by calendar fields.
    * @internal
    */
   U_I18N_API virtual int32_t handleComputeJulianDay(UCalendarDateFields bestField, UErrorCode& status);

   /**
    * Subclasses must 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 Calendar implementation assumes yearWoy is in extended gregorian form
    * @return the extended year, UCAL_EXTENDED_YEAR
    * @internal
    */
   U_I18N_API virtual int32_t handleGetExtendedYearFromWeekFields(int32_t yearWoy,
                                                                  int32_t woy,
                                                                  UErrorCode& status);

   /**
    * Validate a single field of this calendar.  Subclasses should
    * override this method to validate any calendar-specific fields.
    * Generic fields can be handled by `Calendar::validateField()`.
    * @internal
    */
   U_I18N_API virtual void validateField(UCalendarDateFields field, UErrorCode& status);

#ifndef U_HIDE_INTERNAL_API
   /**
    * Compute the Julian day from fields.  Will determine whether to use
    * the JULIAN_DAY field directly, or other fields.
    * @param status        ICU Error Code
    * @return the julian day
    * @internal
    */
   U_I18N_API int32_t computeJulianDay(UErrorCode& status);

   /**
    * Compute the milliseconds in the day from the fields.  This is a
    * value from 0 to 23:59:59.999 inclusive, unless fields are out of
    * range, in which case it can be an arbitrary value.  This value
    * reflects local zone wall time.
    * @internal
    */
   U_I18N_API double computeMillisInDay();

   /**
    * This method can assume EXTENDED_YEAR has been set.
    * @param millis milliseconds of the date fields
    * @param millisInDay milliseconds of the time fields; may be out
    * or range.
    * @param ec Output param set to failure code on function return
    *          when this function fails.
    * @internal
    */
   U_I18N_API int32_t computeZoneOffset(double millis, double millisInDay, UErrorCode& ec);

   /**
    * Determine the best stamp in a range.
    * @param start first enum to look at
    * @param end last enum to look at
    * @param bestSoFar stamp prior to function call
    * @return the stamp value of the best stamp
    * @internal
    */
   U_I18N_API int32_t newestStamp(UCalendarDateFields start,
                                  UCalendarDateFields end,
                                  int32_t bestSoFar) const;

   /**
    * Marker for end of resolve set (row or group). Value for field resolution tables.
    *
    * @see #resolveFields
    * @internal
    */
   U_I18N_API static constexpr int32_t kResolveSTOP = -1;

   /**
    * Value to be bitwised "ORed" against resolve table field values for remapping.
    * Example: (UCAL_DATE | kResolveRemap) in 1st column will cause 'UCAL_DATE' to be returned,
    * but will not examine the value of UCAL_DATE.
    * Value for field resolution tables.
    *
    * @see #resolveFields
    * @internal
    */
   U_I18N_API static constexpr int32_t kResolveRemap = 32;

   /**
    * Precedence table for Dates
    * @see #resolveFields
    * @internal
    */
   U_I18N_API static const UFieldResolutionTable kDatePrecedence[];

   /**
    * Precedence table for Year
    * @see #resolveFields
    * @internal
    */
   U_I18N_API static const UFieldResolutionTable kYearPrecedence[];

   /**
    * Precedence table for Day of Week
    * @see #resolveFields
    * @internal
    */
   U_I18N_API static const UFieldResolutionTable kDOWPrecedence[];

   /**
    * Precedence table for Months
    * @see #resolveFields
    * @internal
    */
   U_I18N_API static const UFieldResolutionTable kMonthPrecedence[];

   /**
    * Given a precedence table, return the newest field combination in
    * the table, or UCAL_FIELD_COUNT if none is found.
    *
    * <p>The precedence table is a 3-dimensional array of integers.  It
    * may be thought of as an array of groups.  Each group is an array of
    * lines.  Each line is an array of field numbers.  Within a line, if
    * all fields are set, then the time stamp of the line is taken to be
    * the stamp of the most recently set field.  If any field of a line is
    * unset, then the line fails to match.  Within a group, the line with
    * the newest time stamp is selected.  The first field of the line is
    * returned to indicate which line matched.
    *
    * <p>In some cases, it may be desirable to map a line to field that
    * whose stamp is NOT examined.  For example, if the best field is
    * DAY_OF_WEEK then the DAY_OF_WEEK_IN_MONTH algorithm may be used.  In
    * order to do this, insert the value <code>kResolveRemap | F</code> at
    * the start of the line, where <code>F</code> is the desired return
    * field value.  This field will NOT be examined; it only determines
    * the return value if the other fields in the line are the newest.
    *
    * <p>If all lines of a group contain at least one unset field, then no
    * line will match, and the group as a whole will fail to match.  In
    * that case, the next group will be processed.  If all groups fail to
    * match, then UCAL_FIELD_COUNT is returned.
    * @internal
    */
   U_I18N_API UCalendarDateFields resolveFields(const UFieldResolutionTable* precedenceTable) const;
#endif  /* U_HIDE_INTERNAL_API */

   /**
    * @internal
    */
   U_I18N_API virtual const UFieldResolutionTable* getFieldResolutionTable() const;

#ifndef U_HIDE_INTERNAL_API
   /**
    * Return the field that is newer, either defaultField, or
    * alternateField.  If neither is newer or neither is set, return defaultField.
    * @internal
    */
   U_I18N_API UCalendarDateFields newerField(UCalendarDateFields defaultField,
                                             UCalendarDateFields alternateField) const;
#endif  /* U_HIDE_INTERNAL_API */


private:
   /**
    * Helper function for calculating limits by trial and error
    * @param field The field being investigated
    * @param startValue starting (least max) value of field
    * @param endValue ending (greatest max) value of field
    * @param status return type
    */
   int32_t getActualHelper(UCalendarDateFields field, int32_t startValue, int32_t endValue, UErrorCode &status) const;

protected:
   /**
    * Get the current time without recomputing.
    *
    * @return     the current time without recomputing.
    * @stable ICU 2.0
    */
   U_I18N_API UDate internalGetTime() const { return fTime; }

   /**
    * Set the current time without affecting flags or fields.
    *
    * @param time    The time to be set
    * @return        the current time without recomputing.
    * @stable ICU 2.0
    */
   U_I18N_API void internalSetTime(UDate time) { fTime = time; }

   /**
    * The time fields containing values into which the millis is computed.
    * @stable ICU 2.0
    */
   int32_t     fFields[UCAL_FIELD_COUNT];

protected:
   /** Special values of stamp[]
    * @stable ICU 2.0
    */
   enum {
       kUnset                 = 0,
       kInternallySet,
       kMinimumUserStamp
   };

private:
   /**
    * Pseudo-time-stamps which specify when each field was set. There
    * are two special values, UNSET and INTERNALLY_SET. Values from
    * MINIMUM_USER_SET to STAMP_MAX are legal user set values.
    */
   int8_t        fStamp[UCAL_FIELD_COUNT];

protected:
   /**
    * 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>
    *
    * Subclasses can refer to the DAY_OF_WEEK and DOW_LOCAL fields, which
    * will be set when this method is called.  Subclasses can also call
    * the getGregorianXxx() methods to obtain Gregorian calendar
    * equivalents for the given Julian day.
    *
    * <p>In addition, subclasses should compute any subclass-specific
    * fields, that is, fields from BASE_FIELD_COUNT to
    * getFieldCount() - 1.
    *
    * <p>The default implementation in <code>Calendar</code> implements
    * a pure proleptic Gregorian calendar.
    * @internal
    */
 U_I18N_API virtual void handleComputeFields(int32_t julianDay, UErrorCode& status);

#ifndef U_HIDE_INTERNAL_API
   /**
    * Return the extended year on the Gregorian calendar as computed by
    * <code>computeGregorianFields()</code>.
    * @internal
    */
   U_I18N_API int32_t getGregorianYear() const {
       return fGregorianYear;
   }

   /**
    * Return the month (0-based) on the Gregorian calendar as computed by
    * <code>computeGregorianFields()</code>.
    * @internal
    */
   U_I18N_API int32_t getGregorianMonth() const {
       return fGregorianMonth;
   }

   /**
    * Return the day of year (1-based) on the Gregorian calendar as
    * computed by <code>computeGregorianFields()</code>.
    * @internal
    */
   U_I18N_API int32_t getGregorianDayOfYear() const {
       return fGregorianDayOfYear;
   }

   /**
    * Return the day of month (1-based) on the Gregorian calendar as
    * computed by <code>computeGregorianFields()</code>.
    * @internal
    */
   U_I18N_API int32_t getGregorianDayOfMonth() const {
     return fGregorianDayOfMonth;
   }
#endif  /* U_HIDE_INTERNAL_API */

   /**
    * Called by computeJulianDay.  Returns the default month (0-based) for the year,
    * taking year and era into account.  Defaults to 0 for Gregorian, which doesn't care.
    * @param eyear The extended year
    * @param status Output param set to failure code on function return
    *          when this function fails.
    * @internal
    */
   U_I18N_API virtual int32_t getDefaultMonthInYear(int32_t eyear, UErrorCode& status);

   /**
    * Called by computeJulianDay.  Returns the default day (1-based) for the month,
    * taking currently-set year and era into account.  Defaults to 1 for Gregorian.
    * @param eyear the extended year
    * @param month the month in the year
    * @param status Output param set to failure code on function return
    *          when this function fails.
    * @internal
    */
   U_I18N_API virtual int32_t getDefaultDayInMonth(int32_t eyear, int32_t month, UErrorCode& status);

   //-------------------------------------------------------------------------
   // Protected utility methods for use by subclasses.  These are very handy
   // for implementing add, roll, and computeFields.
   //-------------------------------------------------------------------------

   /**
    * Adjust the specified field so that it is within
    * the allowable range for the date to which this calendar is set.
    * For example, in a Gregorian calendar pinning the {@link #UCalendarDateFields DAY_OF_MONTH}
    * field for a calendar set to April 31 would cause it to be set
    * to April 30.
    * <p>
    * <b>Subclassing:</b>
    * <br>
    * This utility method is intended for use by subclasses that need to implement
    * their own overrides of {@link #roll roll} and {@link #add add}.
    * <p>
    * <b>Note:</b>
    * <code>pinField</code> is implemented in terms of
    * {@link #getActualMinimum getActualMinimum}
    * and {@link #getActualMaximum getActualMaximum}.  If either of those methods uses
    * a slow, iterative algorithm for a particular field, it would be
    * unwise to attempt to call <code>pinField</code> for that field.  If you
    * really do need to do so, you should override this method to do
    * something more efficient for that field.
    * <p>
    * @param field The calendar field whose value should be pinned.
    * @param status Output param set to failure code on function return
    *          when this function fails.
    *
    * @see #getActualMinimum
    * @see #getActualMaximum
    * @stable ICU 2.0
    */
   U_I18N_API virtual void pinField(UCalendarDateFields field, UErrorCode& status);

   /**
    * Return the week number of a day, within a period. This may be the week number in
    * a year or the week number in a month. Usually this will be a value >= 1, but if
    * some initial days of the period are excluded from week 1, because
    * {@link #getMinimalDaysInFirstWeek getMinimalDaysInFirstWeek} is > 1, then
    * the week number will be zero for those
    * initial days. This method requires the day number and day of week for some
    * known date in the period in order to determine the day of week
    * on the desired day.
    * <p>
    * <b>Subclassing:</b>
    * <br>
    * This method is intended for use by subclasses in implementing their
    * {@link #computeTime computeTime} and/or {@link #computeFields computeFields} methods.
    * It is often useful in {@link #getActualMinimum getActualMinimum} and
    * {@link #getActualMaximum getActualMaximum} as well.
    * <p>
    * This variant is handy for computing the week number of some other
    * day of a period (often the first or last day of the period) when its day
    * of the week is not known but the day number and day of week for some other
    * day in the period (e.g. the current date) <em>is</em> known.
    * <p>
    * @param desiredDay    The {@link #UCalendarDateFields DAY_OF_YEAR} or
    *              {@link #UCalendarDateFields DAY_OF_MONTH} whose week number is desired.
    *              Should be 1 for the first day of the period.
    *
    * @param dayOfPeriod   The {@link #UCalendarDateFields DAY_OF_YEAR}
    *              or {@link #UCalendarDateFields DAY_OF_MONTH} for a day in the period whose
    *              {@link #UCalendarDateFields DAY_OF_WEEK} is specified by the
    *              <code>knownDayOfWeek</code> parameter.
    *              Should be 1 for first day of period.
    *
    * @param dayOfWeek  The {@link #UCalendarDateFields DAY_OF_WEEK} for the day
    *              corresponding to the <code>knownDayOfPeriod</code> parameter.
    *              1-based with 1=Sunday.
    *
    * @return      The week number (one-based), or zero if the day falls before
    *              the first week because
    *              {@link #getMinimalDaysInFirstWeek getMinimalDaysInFirstWeek}
    *              is more than one.
    *
    * @stable ICU 2.8
    */
   U_I18N_API int32_t weekNumber(int32_t desiredDay, int32_t dayOfPeriod, int32_t dayOfWeek);

#ifndef U_HIDE_INTERNAL_API
   /**
    * Return the week number of a day, within a period. This may be the week number in
    * a year, or the week number in a month. Usually this will be a value >= 1, but if
    * some initial days of the period are excluded from week 1, because
    * {@link #getMinimalDaysInFirstWeek getMinimalDaysInFirstWeek} is > 1,
    * then the week number will be zero for those
    * initial days. This method requires the day of week for the given date in order to
    * determine the result.
    * <p>
    * <b>Subclassing:</b>
    * <br>
    * This method is intended for use by subclasses in implementing their
    * {@link #computeTime computeTime} and/or {@link #computeFields computeFields} methods.
    * It is often useful in {@link #getActualMinimum getActualMinimum} and
    * {@link #getActualMaximum getActualMaximum} as well.
    * <p>
    * @param dayOfPeriod   The {@link #UCalendarDateFields DAY_OF_YEAR} or
    *                      {@link #UCalendarDateFields DAY_OF_MONTH} whose week number is desired.
    *                      Should be 1 for the first day of the period.
    *
    * @param dayOfWeek     The {@link #UCalendarDateFields DAY_OF_WEEK} for the day
    *                      corresponding to the <code>dayOfPeriod</code> parameter.
    *                      1-based with 1=Sunday.
    *
    * @return      The week number (one-based), or zero if the day falls before
    *              the first week because
    *              {@link #getMinimalDaysInFirstWeek getMinimalDaysInFirstWeek}
    *              is more than one.
    * @internal
    */
   U_I18N_API inline int32_t weekNumber(int32_t dayOfPeriod, int32_t dayOfWeek);

   /**
    * returns the local DOW, valid range 0..6
    * @internal
    */
   U_I18N_API int32_t getLocalDOW(UErrorCode& status);
#endif  /* U_HIDE_INTERNAL_API */

private:

   /**
    * The next available value for fStamp[]
    */
   int8_t fNextStamp = kMinimumUserStamp;

   /**
    * Recalculates the time stamp array (fStamp).
    * Resets fNextStamp to lowest next stamp value.
    */
   void recalculateStamp();

   /**
    * The current time set for the calendar.
    */
   UDate        fTime = 0;

   /**
    * Time zone affects the time calculation done by Calendar. Calendar subclasses use
    * the time zone data to produce the local time. Always set; never nullptr.
    */
   TimeZone*   fZone = nullptr;

   /**
    * The flag which indicates if the current time is set in the calendar.
    */
   bool      fIsTimeSet:1;

   /**
    * True if the fields are in sync with the currently set time of this Calendar.
    * If false, then the next attempt to get the value of a field will
    * force a recomputation of all fields from the current value of the time
    * field.
    * <P>
    * This should really be named areFieldsInSync, but the old name is retained
    * for backward compatibility.
    */
   bool      fAreFieldsSet:1;

   /**
    * True if all of the fields have been set.  This is initially false, and set to
    * true by computeFields().
    */
   bool      fAreAllFieldsSet:1;

   /**
    * True if all fields have been virtually set, but have not yet been
    * computed.  This occurs only in setTimeInMillis().  A calendar set
    * to this state will compute all fields from the time if it becomes
    * necessary, but otherwise will delay such computation.
    */
   bool      fAreFieldsVirtuallySet:1;

   /**
    * @see   #setLenient
    */
   bool      fLenient:1;

   /**
    * Option for repeated wall time
    * @see #setRepeatedWallTimeOption
    */
   UCalendarWallTimeOption fRepeatedWallTime:3; // Somehow MSVC need 3 bits for UCalendarWallTimeOption

   /**
    * Option for skipped wall time
    * @see #setSkippedWallTimeOption
    */
   UCalendarWallTimeOption fSkippedWallTime:3; // Somehow MSVC need 3 bits for UCalendarWallTimeOption

   /**
    * Both firstDayOfWeek and minimalDaysInFirstWeek are locale-dependent. They are
    * used to figure out the week count for a specific date for a given locale. These
    * must be set when a Calendar is constructed. For example, in US locale,
    * firstDayOfWeek is SUNDAY; minimalDaysInFirstWeek is 1. They are used to figure
    * out the week count for a specific date for a given locale. These must be set when
    * a Calendar is constructed.
    */
   UCalendarDaysOfWeek fFirstDayOfWeek:4; // Somehow MSVC need 4 bits for
                                          // UCalendarDaysOfWeek
   UCalendarDaysOfWeek fWeekendOnset:4; // Somehow MSVC need 4 bits for
                                        // UCalendarDaysOfWeek
   UCalendarDaysOfWeek fWeekendCease:4; // Somehow MSVC need 4 bits for
                                        // UCalendarDaysOfWeek
   uint8_t fMinimalDaysInFirstWeek;
   int32_t fWeekendOnsetMillis;
   int32_t fWeekendCeaseMillis;

   /**
    * Sets firstDayOfWeek and minimalDaysInFirstWeek. Called at Calendar construction
    * time.
    *
    * @param desiredLocale  The given locale.
    * @param type           The calendar type identifier, e.g: gregorian, buddhist, etc.
    * @param success        Indicates the status of setting the week count data from
    *                       the resource for the given locale. Returns U_ZERO_ERROR if
    *                       constructed successfully.
    */
   void        setWeekData(const Locale& desiredLocale, const char *type, UErrorCode& success);

   /**
    * Recompute the time and update the status fields isTimeSet
    * and areFieldsSet.  Callers should check isTimeSet and only
    * call this method if isTimeSet is false.
    *
    * @param status  Output param set to success/failure code on exit. If any value
    *                previously set in the time field is invalid or restricted by
    *                leniency, this will be set to an error status.
    */
   void updateTime(UErrorCode& status);

   /**
    * The Gregorian year, as computed by computeGregorianFields() and
    * returned by getGregorianYear().
    * @see #computeGregorianFields
    */
   int32_t fGregorianYear;

   /**
    * The Gregorian month, as computed by computeGregorianFields() and
    * returned by getGregorianMonth().
    * @see #computeGregorianFields
    */
   int8_t fGregorianMonth;

   /**
    * The Gregorian day of the month, as computed by
    * computeGregorianFields() and returned by getGregorianDayOfMonth().
    * @see #computeGregorianFields
    */
   int8_t fGregorianDayOfMonth;

   /**
    * The Gregorian day of the year, as computed by
    * computeGregorianFields() and returned by getGregorianDayOfYear().
    * @see #computeGregorianFields
    */
   int16_t fGregorianDayOfYear;

   /* calculations */

protected:

   /**
    * Compute the Gregorian calendar year, month, and day of month from the
    * Julian day.  These values are not stored in fields, but in member
    * variables gregorianXxx.  They are used for time zone computations and by
    * subclasses that are Gregorian derivatives.  Subclasses may call this
    * method to perform a Gregorian calendar millis->fields computation.
    */
   U_I18N_API void computeGregorianFields(int32_t julianDay, UErrorCode& ec);

private:

   /**
    * Compute the fields WEEK_OF_YEAR, YEAR_WOY, WEEK_OF_MONTH,
    * DAY_OF_WEEK_IN_MONTH, and DOW_LOCAL from EXTENDED_YEAR, YEAR,
    * DAY_OF_WEEK, and DAY_OF_YEAR.  The latter fields are computed by the
    * subclass based on the calendar system.
    *
    * <p>The YEAR_WOY field is computed simplistically.  It is equal to YEAR
    * most of the time, but at the year boundary it may be adjusted to YEAR-1
    * or YEAR+1 to reflect the overlap of a week into an adjacent year.  In
    * this case, a simple increment or decrement is performed on YEAR, even
    * though this may yield an invalid YEAR value.  For instance, if the YEAR
    * is part of a calendar system with an N-year cycle field CYCLE, then
    * incrementing the YEAR may involve incrementing CYCLE and setting YEAR
    * back to 0 or 1.  This is not handled by this code, and in fact cannot be
    * simply handled without having subclasses define an entire parallel set of
    * fields for fields larger than or equal to a year.  This additional
    * complexity is not warranted, since the intention of the YEAR_WOY field is
    * to support ISO 8601 notation, so it will typically be used with a
    * proleptic Gregorian calendar, which has no field larger than a year.
    */
   void computeWeekFields(UErrorCode &ec);


   /**
    * Ensure that each field is within its valid range by calling {@link
    * #validateField(int, int&)} on each field that has been set.  This method
    * should only be called if this calendar is not lenient.
    * @see #isLenient
    * @see #validateField(int, int&)
    */
   void validateFields(UErrorCode &status);

   /**
    * Validate a single field of this calendar given its minimum and
    * maximum allowed value.  If the field is out of range,
    * <code>U_ILLEGAL_ARGUMENT_ERROR</code> will be set.  Subclasses may
    * use this method in their implementation of {@link
    * #validateField(int, int&)}.
    */
   void validateField(UCalendarDateFields field, int32_t min, int32_t max, UErrorCode& status);

protected:
#ifndef U_HIDE_INTERNAL_API
   /**
    * Convert a quasi Julian date to the day of the week. The Julian date used here is
    * not a true Julian date, since it is measured from midnight, not noon. Return
    * value is one-based.
    *
    * @param julian  The given Julian date number.
    * @return   Day number from 1..7 (SUN..SAT).
    * @internal
    */
   U_I18N_API static uint8_t julianDayToDayOfWeek(int32_t julian);
#endif  /* U_HIDE_INTERNAL_API */

private:
   Locale validLocale;
   Locale actualLocale;

public:
#if !UCONFIG_NO_SERVICE
   /**
    * INTERNAL FOR 2.6 --  Registration.
    */

#ifndef U_HIDE_INTERNAL_API
   /**
    * Return a StringEnumeration over the locales available at the time of the call,
    * including registered locales.
    * @return a StringEnumeration over the locales available at the time of the call
    * @internal
    */
   U_I18N_API static StringEnumeration* getAvailableLocales();

   /**
    * Register a new Calendar factory.  The factory will be adopted.
    * INTERNAL in 2.6
    *
    * Because ICU may choose to cache Calendars internally, this must
    * be called at application startup, prior to any calls to
    * Calendar::createInstance to avoid undefined behavior.
    *
    * @param toAdopt the factory instance to be adopted
    * @param status the in/out status code, no special meanings are assigned
    * @return a registry key that can be used to unregister this factory
    * @internal
    */
   U_I18N_API static URegistryKey registerFactory(ICUServiceFactory* toAdopt, UErrorCode& status);

   /**
    * Unregister a previously-registered CalendarFactory using the key returned from the
    * register call.  Key becomes invalid after a successful call and should not be used again.
    * The CalendarFactory corresponding to the key will be deleted.
    * INTERNAL in 2.6
    *
    * Because ICU may choose to cache Calendars internally, this should
    * be called during application shutdown, after all calls to
    * Calendar::createInstance to avoid undefined behavior.
    *
    * @param key the registry key returned by a previous call to registerFactory
    * @param status the in/out status code, no special meanings are assigned
    * @return true if the factory for the key was successfully unregistered
    * @internal
    */
   U_I18N_API static UBool unregister(URegistryKey key, UErrorCode& status);
#endif  /* U_HIDE_INTERNAL_API */

   /**
    * Multiple Calendar Implementation
    * @internal
    */
   friend class CalendarFactory;

   /**
    * Multiple Calendar Implementation
    * @internal
    */
   friend class CalendarService;

   /**
    * Multiple Calendar Implementation
    * @internal
    */
   friend class DefaultCalendarFactory;
#endif /* !UCONFIG_NO_SERVICE */

   /**
    * @return true if this calendar has a default century (i.e. 03 -> 2003)
    * @internal
    */
   U_I18N_API virtual UBool haveDefaultCentury() const = 0;

   /**
    * @return the start of the default century, as a UDate
    * @internal
    */
   U_I18N_API virtual UDate defaultCenturyStart() const = 0;

   /**
    * @return the beginning year of the default century, as a year
    * @internal
    */
   U_I18N_API virtual int32_t defaultCenturyStartYear() const = 0;

   /** Get the locale for this calendar object. You can choose between valid and actual locale.
    *  @param type type of the locale we're looking for (valid or actual)
    *  @param status error code for the operation
    *  @return the locale
    *  @stable ICU 2.8
    */
   U_I18N_API Locale getLocale(ULocDataLocaleType type, UErrorCode& status) const;

   /**
    * @return      The related Gregorian year; will be obtained by modifying the value
    *              obtained by get from UCAL_EXTENDED_YEAR field
    * @internal
    */
   U_I18N_API virtual int32_t getRelatedYear(UErrorCode& status) const;

   /**
    * @param year  The related Gregorian year to set; will be modified as necessary then
    *              set in UCAL_EXTENDED_YEAR field
    * @internal
    */
   U_I18N_API virtual void setRelatedYear(int32_t year);

#ifndef U_HIDE_INTERNAL_API
   /** Get the locale for this calendar object. You can choose between valid and actual locale.
    *  @param type type of the locale we're looking for (valid or actual)
    *  @param status error code for the operation
    *  @return the locale
    *  @internal
    */
   U_I18N_API const char* getLocaleID(ULocDataLocaleType type, UErrorCode& status) const;
#endif  /* U_HIDE_INTERNAL_API */

private:
   /**
    * Cast TimeZone used by this object to BasicTimeZone, or nullptr if the TimeZone
    * is not an instance of BasicTimeZone.
    */
   BasicTimeZone* getBasicTimeZone() const;

   /**
    * Find the previous zone transition near the given time.
    * @param base The base time, inclusive
    * @param transitionTime Receives the result time
    * @param status The error status
    * @return true if a transition is found.
    */
   UBool getImmediatePreviousZoneTransition(UDate base, UDate *transitionTime, UErrorCode& status) const;

public:
#ifndef U_HIDE_INTERNAL_API
   /**
    * Creates a new Calendar from a Locale for the cache.
    * This method does not set the time or timezone in returned calendar.
    * @param locale the locale.
    * @param status any error returned here.
    * @return the new Calendar object with no time or timezone set.
    * @internal For ICU use only.
    */
   U_I18N_API static Calendar* U_EXPORT2 makeInstance(const Locale& locale, UErrorCode& status);

   /**
    * Get the calendar type for given locale.
    * @param locale the locale
    * @param typeBuffer calendar type returned here
    * @param typeBufferSize The size of typeBuffer in bytes. If the type
    *   can't fit in the buffer, this method sets status to
    *   U_BUFFER_OVERFLOW_ERROR
    * @param status error, if any, returned here.
    * @internal For ICU use only.
    */
   U_I18N_API static void U_EXPORT2 getCalendarTypeFromLocale(const Locale& locale,
                                                              char* typeBuffer,
                                                              int32_t typeBufferSize,
                                                              UErrorCode& status);
#endif  /* U_HIDE_INTERNAL_API */
};

// -------------------------------------

inline Calendar*
Calendar::createInstance(TimeZone* zone, UErrorCode& errorCode)
{
   // since the Locale isn't specified, use the default locale
   return createInstance(zone, Locale::getDefault(), errorCode);
}

// -------------------------------------

inline void
Calendar::roll(UCalendarDateFields field, UBool up, UErrorCode& status)
{
   roll(field, static_cast<int32_t>(up ? +1 : -1), status);
}

#ifndef U_HIDE_DEPRECATED_API
inline void
Calendar::roll(EDateFields field, UBool up, UErrorCode& status)
{
   roll(static_cast<UCalendarDateFields>(field), up, status);
}
#endif  /* U_HIDE_DEPRECATED_API */


// -------------------------------------

/**
* Fast method for subclasses.  The caller must maintain fUserSetDSTOffset and
* fUserSetZoneOffset, as well as the isSet[] array.
*/

inline void
Calendar::internalSet(UCalendarDateFields field, int32_t value)
{
   fFields[field] = value;
   fStamp[field] = kInternallySet;
}

/**
* Macro for the class to declare it override
* haveDefaultCentury, defaultCenturyStart, and
* defaultCenturyStartYear functions in this class.
* @internal
*/
#define DECLARE_OVERRIDE_SYSTEM_DEFAULT_CENTURY \
   virtual UBool haveDefaultCentury() const override; \
   virtual UDate defaultCenturyStart() const override; \
   virtual int32_t defaultCenturyStartYear() const override;

#ifndef U_HIDE_INTERNAL_API
inline int32_t  Calendar::weekNumber(int32_t dayOfPeriod, int32_t dayOfWeek)
{
 return weekNumber(dayOfPeriod, dayOfPeriod, dayOfWeek);
}
#endif  /* U_HIDE_INTERNAL_API */

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */

#endif /* U_SHOW_CPLUSPLUS_API */

#endif // _CALENDAR