xref: /external/icu/icu4c/source/i18n/calendar.cpp

/*
*******************************************************************************
* Copyright (C) 1997-2015, International Business Machines Corporation and    *
* others. All Rights Reserved.                                                *
*******************************************************************************
*
* File CALENDAR.CPP
*
* Modification History:
*
*   Date        Name        Description
*   02/03/97    clhuang     Creation.
*   04/22/97    aliu        Cleaned up, fixed memory leak, made
*                           setWeekCountData() more robust.
*                           Moved platform code to TPlatformUtilities.
*   05/01/97    aliu        Made equals(), before(), after() arguments const.
*   05/20/97    aliu        Changed logic of when to compute fields and time
*                           to fix bugs.
*   08/12/97    aliu        Added equivalentTo.  Misc other fixes.
*   07/28/98    stephen     Sync up with JDK 1.2
*   09/02/98    stephen     Sync with JDK 1.2 8/31 build (getActualMin/Max)
*   03/17/99    stephen     Changed adoptTimeZone() - now fAreFieldsSet is
*                           set to FALSE to force update of time.
*******************************************************************************
*/

#include "utypeinfo.h"  // for 'typeid' to work

#include "unicode/utypes.h"

#if !UCONFIG_NO_FORMATTING

#include "unicode/gregocal.h"
#include "unicode/basictz.h"
#include "unicode/simpletz.h"
#include "unicode/rbtz.h"
#include "unicode/vtzone.h"
#include "gregoimp.h"
#include "buddhcal.h"
#include "taiwncal.h"
#include "japancal.h"
#include "islamcal.h"
#include "hebrwcal.h"
#include "persncal.h"
#include "indiancal.h"
#include "chnsecal.h"
#include "coptccal.h"
#include "dangical.h"
#include "ethpccal.h"
#include "unicode/calendar.h"
#include "cpputils.h"
#include "servloc.h"
#include "ucln_in.h"
#include "cstring.h"
#include "locbased.h"
#include "uresimp.h"
#include "ustrenum.h"
#include "uassert.h"
#include "olsontz.h"
#include "sharedcalendar.h"
#include "unifiedcache.h"

#if !UCONFIG_NO_SERVICE
static icu::ICULocaleService* gService = NULL;
static icu::UInitOnce gServiceInitOnce = U_INITONCE_INITIALIZER;
#endif

// INTERNAL - for cleanup

U_CDECL_BEGIN
static UBool calendar_cleanup(void) {
#if !UCONFIG_NO_SERVICE
    if (gService) {
        delete gService;
        gService = NULL;
    }
    gServiceInitOnce.reset();
#endif
    return TRUE;
}
U_CDECL_END

// ------------------------------------------
//
// Registration
//
//-------------------------------------------
//#define U_DEBUG_CALSVC 1
//

#if defined( U_DEBUG_CALSVC ) || defined (U_DEBUG_CAL)

/**
 * fldName was removed as a duplicate implementation.
 * use  udbg_ services instead,
 * which depend on include files and library from ../tools/toolutil, the following circular link:
 *   CPPFLAGS+=-I$(top_srcdir)/tools/toolutil
 *   LIBS+=$(LIBICUTOOLUTIL)
 */
#include "udbgutil.h"
#include <stdio.h>

/**
* convert a UCalendarDateFields into a string - for debugging
* @param f field enum
* @return static string to the field name
* @internal
*/

const char* fldName(UCalendarDateFields f) {
    return udbg_enumName(UDBG_UCalendarDateFields, (int32_t)f);
}

#if UCAL_DEBUG_DUMP
// from CalendarTest::calToStr - but doesn't modify contents.
void ucal_dump(const Calendar &cal) {
    cal.dump();
}

void Calendar::dump() const {
    int i;
    fprintf(stderr, "@calendar=%s, timeset=%c, fieldset=%c, allfields=%c, virtualset=%c, t=%.2f",
        getType(), fIsTimeSet?'y':'n',  fAreFieldsSet?'y':'n',  fAreAllFieldsSet?'y':'n',
        fAreFieldsVirtuallySet?'y':'n',
        fTime);

    // can add more things here: DST, zone, etc.
    fprintf(stderr, "\n");
    for(i = 0;i<UCAL_FIELD_COUNT;i++) {
        int n;
        const char *f = fldName((UCalendarDateFields)i);
        fprintf(stderr, "  %25s: %-11ld", f, fFields[i]);
        if(fStamp[i] == kUnset) {
            fprintf(stderr, " (unset) ");
        } else if(fStamp[i] == kInternallySet) {
            fprintf(stderr, " (internally set) ");
            //} else if(fStamp[i] == kInternalDefault) {
            //    fprintf(stderr, " (internal default) ");
        } else {
            fprintf(stderr, " %%%d ", fStamp[i]);
        }
        fprintf(stderr, "\n");

    }
}

U_CFUNC void ucal_dump(UCalendar* cal) {
    ucal_dump( *((Calendar*)cal)  );
}
#endif

#endif

/* Max value for stamp allowable before recalculation */
#define STAMP_MAX 10000

static const char * const gCalTypes[] = {
    "gregorian",
    "japanese",
    "buddhist",
    "roc",
    "persian",
    "islamic-civil",
    "islamic",
    "hebrew",
    "chinese",
    "indian",
    "coptic",
    "ethiopic",
    "ethiopic-amete-alem",
    "iso8601",
    "dangi",
    "islamic-umalqura",
    "islamic-tbla",
    "islamic-rgsa",
    NULL
};

// Must be in the order of gCalTypes above
typedef enum ECalType {
    CALTYPE_UNKNOWN = -1,
    CALTYPE_GREGORIAN = 0,
    CALTYPE_JAPANESE,
    CALTYPE_BUDDHIST,
    CALTYPE_ROC,
    CALTYPE_PERSIAN,
    CALTYPE_ISLAMIC_CIVIL,
    CALTYPE_ISLAMIC,
    CALTYPE_HEBREW,
    CALTYPE_CHINESE,
    CALTYPE_INDIAN,
    CALTYPE_COPTIC,
    CALTYPE_ETHIOPIC,
    CALTYPE_ETHIOPIC_AMETE_ALEM,
    CALTYPE_ISO8601,
    CALTYPE_DANGI,
    CALTYPE_ISLAMIC_UMALQURA,
    CALTYPE_ISLAMIC_TBLA,
    CALTYPE_ISLAMIC_RGSA
} ECalType;

U_NAMESPACE_BEGIN

SharedCalendar::~SharedCalendar() {
    delete ptr;
}

template<> U_I18N_API
const SharedCalendar *LocaleCacheKey<SharedCalendar>::createObject(
        const void * /*unusedCreationContext*/, UErrorCode &status) const {
    Calendar *calendar = Calendar::makeInstance(fLoc, status);
    if (U_FAILURE(status)) {
        return NULL;
    }
    SharedCalendar *shared = new SharedCalendar(calendar);
    if (shared == NULL) {
        delete calendar;
        status = U_MEMORY_ALLOCATION_ERROR;
        return NULL;
    }
    shared->addRef();
    return shared;
}

static ECalType getCalendarType(const char *s) {
    for (int i = 0; gCalTypes[i] != NULL; i++) {
        if (uprv_stricmp(s, gCalTypes[i]) == 0) {
            return (ECalType)i;
        }
    }
    return CALTYPE_UNKNOWN;
}

static UBool isStandardSupportedKeyword(const char *keyword, UErrorCode& status) {
    if(U_FAILURE(status)) {
        return FALSE;
    }
    ECalType calType = getCalendarType(keyword);
    return (calType != CALTYPE_UNKNOWN);
}

static void getCalendarKeyword(const UnicodeString &id, char *targetBuffer, int32_t targetBufferSize) {
    UnicodeString calendarKeyword = UNICODE_STRING_SIMPLE("calendar=");
    int32_t calKeyLen = calendarKeyword.length();
    int32_t keyLen = 0;

    int32_t keywordIdx = id.indexOf((UChar)0x003D); /* '=' */
    if (id[0] == 0x40/*'@'*/
        && id.compareBetween(1, keywordIdx+1, calendarKeyword, 0, calKeyLen) == 0)
    {
        keyLen = id.extract(keywordIdx+1, id.length(), targetBuffer, targetBufferSize, US_INV);
    }
    targetBuffer[keyLen] = 0;
}

static ECalType getCalendarTypeForLocale(const char *locid) {
    UErrorCode status = U_ZERO_ERROR;
    ECalType calType = CALTYPE_UNKNOWN;

    //TODO: ULOC_FULL_NAME is out of date and too small..
    char canonicalName[256];

    // canonicalize, so grandfathered variant will be transformed to keywords
    // e.g ja_JP_TRADITIONAL -> ja_JP@calendar=japanese
    int32_t canonicalLen = uloc_canonicalize(locid, canonicalName, sizeof(canonicalName) - 1, &status);
    if (U_FAILURE(status)) {
        return CALTYPE_GREGORIAN;
    }
    canonicalName[canonicalLen] = 0;    // terminate

    char calTypeBuf[32];
    int32_t calTypeBufLen;

    calTypeBufLen = uloc_getKeywordValue(canonicalName, "calendar", calTypeBuf, sizeof(calTypeBuf) - 1, &status);
    if (U_SUCCESS(status)) {
        calTypeBuf[calTypeBufLen] = 0;
        calType = getCalendarType(calTypeBuf);
        if (calType != CALTYPE_UNKNOWN) {
            return calType;
        }
    }
    status = U_ZERO_ERROR;

    // when calendar keyword is not available or not supported, read supplementalData
    // to get the default calendar type for the locale's region
    char region[ULOC_COUNTRY_CAPACITY];
    int32_t regionLen = 0;
    regionLen = uloc_getCountry(canonicalName, region, sizeof(region) - 1, &status);
    if (regionLen == 0) {
        char fullLoc[256];
        uloc_addLikelySubtags(locid, fullLoc, sizeof(fullLoc) - 1, &status);
        regionLen = uloc_getCountry(fullLoc, region, sizeof(region) - 1, &status);
    }
    if (U_FAILURE(status)) {
        return CALTYPE_GREGORIAN;
    }
    region[regionLen] = 0;

    // Read preferred calendar values from supplementalData calendarPreference
    UResourceBundle *rb = ures_openDirect(NULL, "supplementalData", &status);
    ures_getByKey(rb, "calendarPreferenceData", rb, &status);
    UResourceBundle *order = ures_getByKey(rb, region, NULL, &status);
    if (status == U_MISSING_RESOURCE_ERROR && rb != NULL) {
        status = U_ZERO_ERROR;
        order = ures_getByKey(rb, "001", NULL, &status);
    }

    calTypeBuf[0] = 0;
    if (U_SUCCESS(status) && order != NULL) {
        // the first calender type is the default for the region
        int32_t len = 0;
        const UChar *uCalType = ures_getStringByIndex(order, 0, &len, &status);
        if (len < (int32_t)sizeof(calTypeBuf)) {
            u_UCharsToChars(uCalType, calTypeBuf, len);
            *(calTypeBuf + len) = 0; // terminate;
            calType = getCalendarType(calTypeBuf);
        }
    }

    ures_close(order);
    ures_close(rb);

    if (calType == CALTYPE_UNKNOWN) {
        // final fallback
        calType = CALTYPE_GREGORIAN;
    }
    return calType;
}

static Calendar *createStandardCalendar(ECalType calType, const Locale &loc, UErrorCode& status) {
    Calendar *cal = NULL;

    switch (calType) {
        case CALTYPE_GREGORIAN:
            cal = new GregorianCalendar(loc, status);
            break;
        case CALTYPE_JAPANESE:
            cal = new JapaneseCalendar(loc, status);
            break;
        case CALTYPE_BUDDHIST:
            cal = new BuddhistCalendar(loc, status);
            break;
        case CALTYPE_ROC:
            cal = new TaiwanCalendar(loc, status);
            break;
        case CALTYPE_PERSIAN:
            cal = new PersianCalendar(loc, status);
            break;
        case CALTYPE_ISLAMIC_TBLA:
            cal = new IslamicCalendar(loc, status, IslamicCalendar::TBLA);
            break;
        case CALTYPE_ISLAMIC_CIVIL:
            cal = new IslamicCalendar(loc, status, IslamicCalendar::CIVIL);
            break;
        case CALTYPE_ISLAMIC_RGSA:
            // default any region specific not handled individually to islamic
        case CALTYPE_ISLAMIC:
            cal = new IslamicCalendar(loc, status, IslamicCalendar::ASTRONOMICAL);
            break;
        case CALTYPE_ISLAMIC_UMALQURA:
            cal = new IslamicCalendar(loc, status, IslamicCalendar::UMALQURA);
            break;
        case CALTYPE_HEBREW:
            cal = new HebrewCalendar(loc, status);
            break;
        case CALTYPE_CHINESE:
            cal = new ChineseCalendar(loc, status);
            break;
        case CALTYPE_INDIAN:
            cal = new IndianCalendar(loc, status);
            break;
        case CALTYPE_COPTIC:
            cal = new CopticCalendar(loc, status);
            break;
        case CALTYPE_ETHIOPIC:
            cal = new EthiopicCalendar(loc, status, EthiopicCalendar::AMETE_MIHRET_ERA);
            break;
        case CALTYPE_ETHIOPIC_AMETE_ALEM:
            cal = new EthiopicCalendar(loc, status, EthiopicCalendar::AMETE_ALEM_ERA);
            break;
        case CALTYPE_ISO8601:
            cal = new GregorianCalendar(loc, status);
            cal->setFirstDayOfWeek(UCAL_MONDAY);
            cal->setMinimalDaysInFirstWeek(4);
            break;
        case CALTYPE_DANGI:
            cal = new DangiCalendar(loc, status);
            break;
        default:
            status = U_UNSUPPORTED_ERROR;
    }
    return cal;
}


#if !UCONFIG_NO_SERVICE

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

/**
* a Calendar Factory which creates the "basic" calendar types, that is, those
* shipped with ICU.
*/
class BasicCalendarFactory : public LocaleKeyFactory {
public:
    /**
    * @param calendarType static const string (caller owns storage - will be aliased) to calendar type
    */
    BasicCalendarFactory()
        : LocaleKeyFactory(LocaleKeyFactory::INVISIBLE) { }

    virtual ~BasicCalendarFactory();

protected:
    //virtual UBool isSupportedID( const UnicodeString& id, UErrorCode& status) const {
    //  if(U_FAILURE(status)) {
    //    return FALSE;
    //  }
    //  char keyword[ULOC_FULLNAME_CAPACITY];
    //  getCalendarKeyword(id, keyword, (int32_t)sizeof(keyword));
    //  return isStandardSupportedKeyword(keyword, status);
    //}

    virtual void updateVisibleIDs(Hashtable& result, UErrorCode& status) const
    {
        if (U_SUCCESS(status)) {
            for(int32_t i=0;gCalTypes[i] != NULL;i++) {
                UnicodeString id((UChar)0x40); /* '@' a variant character */
                id.append(UNICODE_STRING_SIMPLE("calendar="));
                id.append(UnicodeString(gCalTypes[i], -1, US_INV));
                result.put(id, (void*)this, status);
            }
        }
    }

    virtual UObject* create(const ICUServiceKey& key, const ICUService* /*service*/, UErrorCode& status) const {
#ifdef U_DEBUG_CALSVC
        if(dynamic_cast<const LocaleKey*>(&key) == NULL) {
            fprintf(stderr, "::create - not a LocaleKey!\n");
        }
#endif
        const LocaleKey& lkey = (LocaleKey&)key;
        Locale curLoc;  // current locale
        Locale canLoc;  // Canonical locale

        lkey.currentLocale(curLoc);
        lkey.canonicalLocale(canLoc);

        char keyword[ULOC_FULLNAME_CAPACITY];
        UnicodeString str;

        key.currentID(str);
        getCalendarKeyword(str, keyword, (int32_t) sizeof(keyword));

#ifdef U_DEBUG_CALSVC
        fprintf(stderr, "BasicCalendarFactory::create() - cur %s, can %s\n", (const char*)curLoc.getName(), (const char*)canLoc.getName());
#endif

        if(!isStandardSupportedKeyword(keyword,status)) {  // Do we handle this type?
#ifdef U_DEBUG_CALSVC

            fprintf(stderr, "BasicCalendarFactory - not handling %s.[%s]\n", (const char*) curLoc.getName(), tmp );
#endif
            return NULL;
        }

        return createStandardCalendar(getCalendarType(keyword), canLoc, status);
    }
};

BasicCalendarFactory::~BasicCalendarFactory() {}

/**
* A factory which looks up the DefaultCalendar resource to determine which class of calendar to use
*/

class DefaultCalendarFactory : public ICUResourceBundleFactory {
public:
    DefaultCalendarFactory() : ICUResourceBundleFactory() { }
    virtual ~DefaultCalendarFactory();
protected:
    virtual UObject* create(const ICUServiceKey& key, const ICUService* /*service*/, UErrorCode& status) const  {

        LocaleKey &lkey = (LocaleKey&)key;
        Locale loc;
        lkey.currentLocale(loc);

        UnicodeString *ret = new UnicodeString();
        if (ret == NULL) {
            status = U_MEMORY_ALLOCATION_ERROR;
        } else {
            ret->append((UChar)0x40); // '@' is a variant character
            ret->append(UNICODE_STRING("calendar=", 9));
            ret->append(UnicodeString(gCalTypes[getCalendarTypeForLocale(loc.getName())], -1, US_INV));
        }
        return ret;
    }
};

DefaultCalendarFactory::~DefaultCalendarFactory() {}

// -------------------------------------
class CalendarService : public ICULocaleService {
public:
    CalendarService()
        : ICULocaleService(UNICODE_STRING_SIMPLE("Calendar"))
    {
        UErrorCode status = U_ZERO_ERROR;
        registerFactory(new DefaultCalendarFactory(), status);
    }

    virtual ~CalendarService();

    virtual UObject* cloneInstance(UObject* instance) const {
        UnicodeString *s = dynamic_cast<UnicodeString *>(instance);
        if(s != NULL) {
            return s->clone();
        } else {
#ifdef U_DEBUG_CALSVC_F
            UErrorCode status2 = U_ZERO_ERROR;
            fprintf(stderr, "Cloning a %s calendar with tz=%ld\n", ((Calendar*)instance)->getType(), ((Calendar*)instance)->get(UCAL_ZONE_OFFSET, status2));
#endif
            return ((Calendar*)instance)->clone();
        }
    }

    virtual UObject* handleDefault(const ICUServiceKey& key, UnicodeString* /*actualID*/, UErrorCode& status) const {
        LocaleKey& lkey = (LocaleKey&)key;
        //int32_t kind = lkey.kind();

        Locale loc;
        lkey.canonicalLocale(loc);

#ifdef U_DEBUG_CALSVC
        Locale loc2;
        lkey.currentLocale(loc2);
        fprintf(stderr, "CalSvc:handleDefault for currentLoc %s, canloc %s\n", (const char*)loc.getName(),  (const char*)loc2.getName());
#endif
        Calendar *nc =  new GregorianCalendar(loc, status);

#ifdef U_DEBUG_CALSVC
        UErrorCode status2 = U_ZERO_ERROR;
        fprintf(stderr, "New default calendar has tz=%d\n", ((Calendar*)nc)->get(UCAL_ZONE_OFFSET, status2));
#endif
        return nc;
    }

    virtual UBool isDefault() const {
        return countFactories() == 1;
    }
};

CalendarService::~CalendarService() {}

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

static inline UBool
isCalendarServiceUsed() {
    return !gServiceInitOnce.isReset();
}

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

static void U_CALLCONV
initCalendarService(UErrorCode &status)
{
#ifdef U_DEBUG_CALSVC
        fprintf(stderr, "Spinning up Calendar Service\n");
#endif
    ucln_i18n_registerCleanup(UCLN_I18N_CALENDAR, calendar_cleanup);
    gService = new CalendarService();
    if (gService == NULL) {
            status = U_MEMORY_ALLOCATION_ERROR;
        return;
        }
#ifdef U_DEBUG_CALSVC
        fprintf(stderr, "Registering classes..\n");
#endif

        // Register all basic instances.
    gService->registerFactory(new BasicCalendarFactory(),status);

#ifdef U_DEBUG_CALSVC
        fprintf(stderr, "Done..\n");
#endif

        if(U_FAILURE(status)) {
#ifdef U_DEBUG_CALSVC
            fprintf(stderr, "err (%s) registering classes, deleting service.....\n", u_errorName(status));
#endif
        delete gService;
        gService = NULL;
    }
        }

static ICULocaleService*
getCalendarService(UErrorCode &status)
{
    umtx_initOnce(gServiceInitOnce, &initCalendarService, status);
    return gService;
}

URegistryKey Calendar::registerFactory(ICUServiceFactory* toAdopt, UErrorCode& status)
{
    return getCalendarService(status)->registerFactory(toAdopt, status);
}

UBool Calendar::unregister(URegistryKey key, UErrorCode& status) {
    return getCalendarService(status)->unregister(key, status);
}
#endif /* UCONFIG_NO_SERVICE */

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

static const int32_t kCalendarLimits[UCAL_FIELD_COUNT][4] = {
    //    Minimum  Greatest min      Least max   Greatest max
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // ERA
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // YEAR
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // MONTH
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // WEEK_OF_YEAR
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // WEEK_OF_MONTH
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // DAY_OF_MONTH
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // DAY_OF_YEAR
    {           1,            1,             7,             7  }, // DAY_OF_WEEK
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // DAY_OF_WEEK_IN_MONTH
    {           0,            0,             1,             1  }, // AM_PM
    {           0,            0,            11,            11  }, // HOUR
    {           0,            0,            23,            23  }, // HOUR_OF_DAY
    {           0,            0,            59,            59  }, // MINUTE
    {           0,            0,            59,            59  }, // SECOND
    {           0,            0,           999,           999  }, // MILLISECOND
    {-12*kOneHour, -12*kOneHour,   12*kOneHour,   15*kOneHour  }, // ZONE_OFFSET
    {           0,            0,    1*kOneHour,    1*kOneHour  }, // DST_OFFSET
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // YEAR_WOY
    {           1,            1,             7,             7  }, // DOW_LOCAL
    {/*N/A*/-1,       /*N/A*/-1,     /*N/A*/-1,       /*N/A*/-1}, // EXTENDED_YEAR
    { -0x7F000000,  -0x7F000000,    0x7F000000,    0x7F000000  }, // JULIAN_DAY
    {           0,            0, 24*kOneHour-1, 24*kOneHour-1  }, // MILLISECONDS_IN_DAY
    {           0,            0,             1,             1  }, // IS_LEAP_MONTH
};

// Resource bundle tags read by this class
static const char gMonthNames[] = "monthNames";

// Data flow in Calendar
// ---------------------

// The current time is represented in two ways by Calendar: as UTC
// milliseconds from the epoch start (1 January 1970 0:00 UTC), and as local
// fields such as MONTH, HOUR, AM_PM, etc.  It is possible to compute the
// millis from the fields, and vice versa.  The data needed to do this
// conversion is encapsulated by a TimeZone object owned by the Calendar.
// The data provided by the TimeZone object may also be overridden if the
// user sets the ZONE_OFFSET and/or DST_OFFSET fields directly. The class
// keeps track of what information was most recently set by the caller, and
// uses that to compute any other information as needed.

// If the user sets the fields using set(), the data flow is as follows.
// This is implemented by the Calendar subclass's computeTime() method.
// During this process, certain fields may be ignored.  The disambiguation
// algorithm for resolving which fields to pay attention to is described
// above.

//   local fields (YEAR, MONTH, DATE, HOUR, MINUTE, etc.)
//           |
//           | Using Calendar-specific algorithm
//           V
//   local standard millis
//           |
//           | Using TimeZone or user-set ZONE_OFFSET / DST_OFFSET
//           V
//   UTC millis (in time data member)

// If the user sets the UTC millis using setTime(), the data flow is as
// follows.  This is implemented by the Calendar subclass's computeFields()
// method.

//   UTC millis (in time data member)
//           |
//           | Using TimeZone getOffset()
//           V
//   local standard millis
//           |
//           | Using Calendar-specific algorithm
//           V
//   local fields (YEAR, MONTH, DATE, HOUR, MINUTE, etc.)

// In general, a round trip from fields, through local and UTC millis, and
// back out to fields is made when necessary.  This is implemented by the
// complete() method.  Resolving a partial set of fields into a UTC millis
// value allows all remaining fields to be generated from that value.  If
// the Calendar is lenient, the fields are also renormalized to standard
// ranges when they are regenerated.

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

Calendar::Calendar(UErrorCode& success)
:   UObject(),
fIsTimeSet(FALSE),
fAreFieldsSet(FALSE),
fAreAllFieldsSet(FALSE),
fAreFieldsVirtuallySet(FALSE),
fNextStamp((int32_t)kMinimumUserStamp),
fTime(0),
fLenient(TRUE),
fZone(NULL),
fRepeatedWallTime(UCAL_WALLTIME_LAST),
fSkippedWallTime(UCAL_WALLTIME_LAST)
{
    clear();
    if (U_FAILURE(success)) {
        return;
    }
    fZone = TimeZone::createDefault();
    if (fZone == NULL) {
        success = U_MEMORY_ALLOCATION_ERROR;
    }
    setWeekData(Locale::getDefault(), NULL, success);
}

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

Calendar::Calendar(TimeZone* zone, const Locale& aLocale, UErrorCode& success)
:   UObject(),
fIsTimeSet(FALSE),
fAreFieldsSet(FALSE),
fAreAllFieldsSet(FALSE),
fAreFieldsVirtuallySet(FALSE),
fNextStamp((int32_t)kMinimumUserStamp),
fTime(0),
fLenient(TRUE),
fZone(NULL),
fRepeatedWallTime(UCAL_WALLTIME_LAST),
fSkippedWallTime(UCAL_WALLTIME_LAST)
{
    if (U_FAILURE(success)) {
        return;
    }
    if(zone == 0) {
#if defined (U_DEBUG_CAL)
        fprintf(stderr, "%s:%d: ILLEGAL ARG because timezone cannot be 0\n",
            __FILE__, __LINE__);
#endif
        success = U_ILLEGAL_ARGUMENT_ERROR;
        return;
    }

    clear();
    fZone = zone;
    setWeekData(aLocale, NULL, success);
}

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

Calendar::Calendar(const TimeZone& zone, const Locale& aLocale, UErrorCode& success)
:   UObject(),
fIsTimeSet(FALSE),
fAreFieldsSet(FALSE),
fAreAllFieldsSet(FALSE),
fAreFieldsVirtuallySet(FALSE),
fNextStamp((int32_t)kMinimumUserStamp),
fTime(0),
fLenient(TRUE),
fZone(NULL),
fRepeatedWallTime(UCAL_WALLTIME_LAST),
fSkippedWallTime(UCAL_WALLTIME_LAST)
{
    if (U_FAILURE(success)) {
        return;
    }
    clear();
    fZone = zone.clone();
    if (fZone == NULL) {
        success = U_MEMORY_ALLOCATION_ERROR;
    }
    setWeekData(aLocale, NULL, success);
}

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

Calendar::~Calendar()
{
    delete fZone;
}

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

Calendar::Calendar(const Calendar &source)
:   UObject(source)
{
    fZone = NULL;
    *this = source;
}

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

Calendar &
Calendar::operator=(const Calendar &right)
{
    if (this != &right) {
        uprv_arrayCopy(right.fFields, fFields, UCAL_FIELD_COUNT);
        uprv_arrayCopy(right.fIsSet, fIsSet, UCAL_FIELD_COUNT);
        uprv_arrayCopy(right.fStamp, fStamp, UCAL_FIELD_COUNT);
        fTime                    = right.fTime;
        fIsTimeSet               = right.fIsTimeSet;
        fAreAllFieldsSet         = right.fAreAllFieldsSet;
        fAreFieldsSet            = right.fAreFieldsSet;
        fAreFieldsVirtuallySet   = right.fAreFieldsVirtuallySet;
        fLenient                 = right.fLenient;
        fRepeatedWallTime        = right.fRepeatedWallTime;
        fSkippedWallTime         = right.fSkippedWallTime;
        delete fZone;
        fZone = NULL;
        if (right.fZone != NULL) {
            fZone                = right.fZone->clone();
        }
        fFirstDayOfWeek          = right.fFirstDayOfWeek;
        fMinimalDaysInFirstWeek  = right.fMinimalDaysInFirstWeek;
        fWeekendOnset            = right.fWeekendOnset;
        fWeekendOnsetMillis      = right.fWeekendOnsetMillis;
        fWeekendCease            = right.fWeekendCease;
        fWeekendCeaseMillis      = right.fWeekendCeaseMillis;
        fNextStamp               = right.fNextStamp;
        uprv_strcpy(validLocale, right.validLocale);
        uprv_strcpy(actualLocale, right.actualLocale);
    }

    return *this;
}

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

Calendar* U_EXPORT2
Calendar::createInstance(UErrorCode& success)
{
    return createInstance(TimeZone::createDefault(), Locale::getDefault(), success);
}

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

Calendar* U_EXPORT2
Calendar::createInstance(const TimeZone& zone, UErrorCode& success)
{
    return createInstance(zone, Locale::getDefault(), success);
}

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

Calendar* U_EXPORT2
Calendar::createInstance(const Locale& aLocale, UErrorCode& success)
{
    return createInstance(TimeZone::createDefault(), aLocale, success);
}

// ------------------------------------- Adopting

// Note: this is the bottleneck that actually calls the service routines.

Calendar * U_EXPORT2
Calendar::makeInstance(const Locale& aLocale, UErrorCode& success) {
    if (U_FAILURE(success)) {
        return NULL;
    }

    Locale actualLoc;
    UObject* u = NULL;

#if !UCONFIG_NO_SERVICE
    if (isCalendarServiceUsed()) {
        u = getCalendarService(success)->get(aLocale, LocaleKey::KIND_ANY, &actualLoc, success);
    }
    else
#endif
    {
        u = createStandardCalendar(getCalendarTypeForLocale(aLocale.getName()), aLocale, success);
    }
    Calendar* c = NULL;

    if(U_FAILURE(success) || !u) {
        if(U_SUCCESS(success)) { // Propagate some kind of err
            success = U_INTERNAL_PROGRAM_ERROR;
        }
        return NULL;
    }

#if !UCONFIG_NO_SERVICE
    const UnicodeString* str = dynamic_cast<const UnicodeString*>(u);
    if(str != NULL) {
        // It's a unicode string telling us what type of calendar to load ("gregorian", etc)
        // Create a Locale over this string
        Locale l("");
        LocaleUtility::initLocaleFromName(*str, l);

#ifdef U_DEBUG_CALSVC
        fprintf(stderr, "Calendar::createInstance(%s), looking up [%s]\n", aLocale.getName(), l.getName());
#endif

        Locale actualLoc2;
        delete u;
        u = NULL;

        // Don't overwrite actualLoc, since the actual loc from this call
        // may be something like "@calendar=gregorian" -- TODO investigate
        // further...
        c = (Calendar*)getCalendarService(success)->get(l, LocaleKey::KIND_ANY, &actualLoc2, success);

        if(U_FAILURE(success) || !c) {
            if(U_SUCCESS(success)) {
                success = U_INTERNAL_PROGRAM_ERROR; // Propagate some err
            }
            return NULL;
        }

        str = dynamic_cast<const UnicodeString*>(c);
        if(str != NULL) {
            // recursed! Second lookup returned a UnicodeString.
            // Perhaps DefaultCalendar{} was set to another locale.
#ifdef U_DEBUG_CALSVC
            char tmp[200];
            // Extract a char* out of it..
            int32_t len = str->length();
            int32_t actLen = sizeof(tmp)-1;
            if(len > actLen) {
                len = actLen;
            }
            str->extract(0,len,tmp);
            tmp[len]=0;

            fprintf(stderr, "err - recursed, 2nd lookup was unistring %s\n", tmp);
#endif
            success = U_MISSING_RESOURCE_ERROR;  // requested a calendar type which could NOT be found.
            delete c;
            return NULL;
        }
#ifdef U_DEBUG_CALSVC
        fprintf(stderr, "%p: setting week count data to locale %s, actual locale %s\n", c, (const char*)aLocale.getName(), (const char *)actualLoc.getName());
#endif
        c->setWeekData(aLocale, c->getType(), success);  // set the correct locale (this was an indirected calendar)

        char keyword[ULOC_FULLNAME_CAPACITY];
        UErrorCode tmpStatus = U_ZERO_ERROR;
        l.getKeywordValue("calendar", keyword, ULOC_FULLNAME_CAPACITY, tmpStatus);
        if (U_SUCCESS(tmpStatus) && uprv_strcmp(keyword, "iso8601") == 0) {
            c->setFirstDayOfWeek(UCAL_MONDAY);
            c->setMinimalDaysInFirstWeek(4);
        }
    }
    else
#endif /* UCONFIG_NO_SERVICE */
    {
        // a calendar was returned - we assume the factory did the right thing.
        c = (Calendar*)u;
    }

    return c;
}

Calendar* U_EXPORT2
Calendar::createInstance(TimeZone* zone, const Locale& aLocale, UErrorCode& success)
{
    LocalPointer<TimeZone> zonePtr(zone);
    const SharedCalendar *shared = NULL;
    UnifiedCache::getByLocale(aLocale, shared, success);
    if (U_FAILURE(success)) {
        return NULL;
    }
    Calendar *c = (*shared)->clone();
    shared->removeRef();
    if (c == NULL) {
        success = U_MEMORY_ALLOCATION_ERROR;
        return NULL;
    }

    // Now, reset calendar to default state:
    c->adoptTimeZone(zonePtr.orphan()); //  Set the correct time zone
    c->setTimeInMillis(getNow(), success); // let the new calendar have the current time.

    return c;
}

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

Calendar* U_EXPORT2
Calendar::createInstance(const TimeZone& zone, const Locale& aLocale, UErrorCode& success)
{
    Calendar* c = createInstance(aLocale, success);
    if(U_SUCCESS(success) && c) {
        c->setTimeZone(zone);
    }
    return c;
}

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

void U_EXPORT2
Calendar::getCalendarTypeFromLocale(
        const Locale &aLocale,
        char *typeBuffer,
        int32_t typeBufferSize,
        UErrorCode &success) {
    const SharedCalendar *shared = NULL;
    UnifiedCache::getByLocale(aLocale, shared, success);
    if (U_FAILURE(success)) {
        return;
    }
    uprv_strncpy(typeBuffer, (*shared)->getType(), typeBufferSize);
    shared->removeRef();
    if (typeBuffer[typeBufferSize - 1]) {
        success = U_BUFFER_OVERFLOW_ERROR;
    }
}

UBool
Calendar::operator==(const Calendar& that) const
{
    UErrorCode status = U_ZERO_ERROR;
    return isEquivalentTo(that) &&
        getTimeInMillis(status) == that.getTimeInMillis(status) &&
        U_SUCCESS(status);
}

UBool
Calendar::isEquivalentTo(const Calendar& other) const
{
    return typeid(*this) == typeid(other) &&
        fLenient                == other.fLenient &&
        fRepeatedWallTime       == other.fRepeatedWallTime &&
        fSkippedWallTime        == other.fSkippedWallTime &&
        fFirstDayOfWeek         == other.fFirstDayOfWeek &&
        fMinimalDaysInFirstWeek == other.fMinimalDaysInFirstWeek &&
        fWeekendOnset           == other.fWeekendOnset &&
        fWeekendOnsetMillis     == other.fWeekendOnsetMillis &&
        fWeekendCease           == other.fWeekendCease &&
        fWeekendCeaseMillis     == other.fWeekendCeaseMillis &&
        *fZone                  == *other.fZone;
}

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

UBool
Calendar::equals(const Calendar& when, UErrorCode& status) const
{
    return (this == &when ||
        getTime(status) == when.getTime(status));
}

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

UBool
Calendar::before(const Calendar& when, UErrorCode& status) const
{
    return (this != &when &&
        getTimeInMillis(status) < when.getTimeInMillis(status));
}

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

UBool
Calendar::after(const Calendar& when, UErrorCode& status) const
{
    return (this != &when &&
        getTimeInMillis(status) > when.getTimeInMillis(status));
}

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


const Locale* U_EXPORT2
Calendar::getAvailableLocales(int32_t& count)
{
    return Locale::getAvailableLocales(count);
}

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

StringEnumeration* U_EXPORT2
Calendar::getKeywordValuesForLocale(const char* key,
                    const Locale& locale, UBool commonlyUsed, UErrorCode& status)
{
    // This is a wrapper over ucal_getKeywordValuesForLocale
    UEnumeration *uenum = ucal_getKeywordValuesForLocale(key, locale.getName(),
                                                        commonlyUsed, &status);
    if (U_FAILURE(status)) {
        uenum_close(uenum);
        return NULL;
    }
    return new UStringEnumeration(uenum);
}

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

UDate U_EXPORT2
Calendar::getNow()
{
    return uprv_getUTCtime(); // return as milliseconds
}

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

/**
* Gets this Calendar's current time as a long.
* @return the current time as UTC milliseconds from the epoch.
*/
double
Calendar::getTimeInMillis(UErrorCode& status) const
{
    if(U_FAILURE(status))
        return 0.0;

    if ( ! fIsTimeSet)
        ((Calendar*)this)->updateTime(status);

    /* Test for buffer overflows */
    if(U_FAILURE(status)) {
        return 0.0;
    }
    return fTime;
}

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

/**
* Sets this Calendar's current time from the given long value.
* A status of U_ILLEGAL_ARGUMENT_ERROR is set when millis is
* outside the range permitted by a Calendar object when not in lenient mode.
* when in lenient mode the out of range values are pinned to their respective min/max.
* @param date the new time in UTC milliseconds from the epoch.
*/
void
Calendar::setTimeInMillis( double millis, UErrorCode& status ) {
    if(U_FAILURE(status))
        return;

    if (millis > MAX_MILLIS) {
        if(isLenient()) {
            millis = MAX_MILLIS;
        } else {
		    status = U_ILLEGAL_ARGUMENT_ERROR;
		    return;
        }
    } else if (millis < MIN_MILLIS) {
        if(isLenient()) {
            millis = MIN_MILLIS;
        } else {
    		status = U_ILLEGAL_ARGUMENT_ERROR;
	    	return;
        }
    }

    fTime = millis;
    fAreFieldsSet = fAreAllFieldsSet = FALSE;
    fIsTimeSet = fAreFieldsVirtuallySet = TRUE;

    for (int32_t i=0; i<UCAL_FIELD_COUNT; ++i) {
        fFields[i]     = 0;
        fStamp[i]     = kUnset;
        fIsSet[i]     = FALSE;
    }


}

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

int32_t
Calendar::get(UCalendarDateFields field, UErrorCode& status) const
{
    // field values are only computed when actually requested; for more on when computation
    // of various things happens, see the "data flow in Calendar" description at the top
    // of this file
    if (U_SUCCESS(status)) ((Calendar*)this)->complete(status); // Cast away const
    return U_SUCCESS(status) ? fFields[field] : 0;
}

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

void
Calendar::set(UCalendarDateFields field, int32_t value)
{
    if (fAreFieldsVirtuallySet) {
        UErrorCode ec = U_ZERO_ERROR;
        computeFields(ec);
    }
    fFields[field]     = value;
    /* Ensure that the fNextStamp value doesn't go pass max value for int32_t */
    if (fNextStamp == STAMP_MAX) {
        recalculateStamp();
    }
    fStamp[field]     = fNextStamp++;
    fIsSet[field]     = TRUE; // Remove later
    fIsTimeSet = fAreFieldsSet = fAreFieldsVirtuallySet = FALSE;
}

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

void
Calendar::set(int32_t year, int32_t month, int32_t date)
{
    set(UCAL_YEAR, year);
    set(UCAL_MONTH, month);
    set(UCAL_DATE, date);
}

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

void
Calendar::set(int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute)
{
    set(UCAL_YEAR, year);
    set(UCAL_MONTH, month);
    set(UCAL_DATE, date);
    set(UCAL_HOUR_OF_DAY, hour);
    set(UCAL_MINUTE, minute);
}

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

void
Calendar::set(int32_t year, int32_t month, int32_t date, int32_t hour, int32_t minute, int32_t second)
{
    set(UCAL_YEAR, year);
    set(UCAL_MONTH, month);
    set(UCAL_DATE, date);
    set(UCAL_HOUR_OF_DAY, hour);
    set(UCAL_MINUTE, minute);
    set(UCAL_SECOND, second);
}

// -------------------------------------
// For now the full getRelatedYear implementation is here;
// per #10752 move the non-default implementation to subclasses
// (default implementation will do no year adjustment)

static int32_t gregoYearFromIslamicStart(int32_t year) {
    // ad hoc conversion, improve under #10752
    // rough est for now, ok for grego 1846-2138,
    // otherwise occasionally wrong (for 3% of years)
    int cycle, offset, shift = 0;
    if (year >= 1397) {
        cycle = (year - 1397) / 67;
        offset = (year - 1397) % 67;
        shift = 2*cycle + ((offset >= 33)? 1: 0);
    } else {
        cycle = (year - 1396) / 67 - 1;
        offset = -(year - 1396) % 67;
        shift = 2*cycle + ((offset <= 33)? 1: 0);
    }
    return year + 579 - shift;
}

int32_t Calendar::getRelatedYear(UErrorCode &status) const
{
    if (U_FAILURE(status)) {
        return 0;
    }
    int32_t year = get(UCAL_EXTENDED_YEAR, status);
    if (U_FAILURE(status)) {
        return 0;
    }
    // modify for calendar type
    ECalType type = getCalendarType(getType());
    switch (type) {
        case CALTYPE_PERSIAN:
            year += 622; break;
        case CALTYPE_HEBREW:
            year -= 3760; break;
        case CALTYPE_CHINESE:
            year -= 2637; break;
        case CALTYPE_INDIAN:
            year += 79; break;
        case CALTYPE_COPTIC:
            year += 284; break;
        case CALTYPE_ETHIOPIC:
            year += 8; break;
        case CALTYPE_ETHIOPIC_AMETE_ALEM:
            year -=5492; break;
        case CALTYPE_DANGI:
            year -= 2333; break;
        case CALTYPE_ISLAMIC_CIVIL:
        case CALTYPE_ISLAMIC:
        case CALTYPE_ISLAMIC_UMALQURA:
        case CALTYPE_ISLAMIC_TBLA:
        case CALTYPE_ISLAMIC_RGSA:
            year = gregoYearFromIslamicStart(year); break;
        default:
            // CALTYPE_GREGORIAN
            // CALTYPE_JAPANESE
            // CALTYPE_BUDDHIST
            // CALTYPE_ROC
            // CALTYPE_ISO8601
            // do nothing, EXTENDED_YEAR same as Gregorian
            break;
    }
    return year;
}

// -------------------------------------
// For now the full setRelatedYear implementation is here;
// per #10752 move the non-default implementation to subclasses
// (default implementation will do no year adjustment)

static int32_t firstIslamicStartYearFromGrego(int32_t year) {
    // ad hoc conversion, improve under #10752
    // rough est for now, ok for grego 1846-2138,
    // otherwise occasionally wrong (for 3% of years)
    int cycle, offset, shift = 0;
    if (year >= 1977) {
        cycle = (year - 1977) / 65;
        offset = (year - 1977) % 65;
        shift = 2*cycle + ((offset >= 32)? 1: 0);
    } else {
        cycle = (year - 1976) / 65 - 1;
        offset = -(year - 1976) % 65;
        shift = 2*cycle + ((offset <= 32)? 1: 0);
    }
    return year - 579 + shift;
}
void Calendar::setRelatedYear(int32_t year)
{
    // modify for calendar type
    ECalType type = getCalendarType(getType());
    switch (type) {
        case CALTYPE_PERSIAN:
            year -= 622; break;
        case CALTYPE_HEBREW:
            year += 3760; break;
        case CALTYPE_CHINESE:
            year += 2637; break;
        case CALTYPE_INDIAN:
            year -= 79; break;
        case CALTYPE_COPTIC:
            year -= 284; break;
        case CALTYPE_ETHIOPIC:
            year -= 8; break;
        case CALTYPE_ETHIOPIC_AMETE_ALEM:
            year +=5492; break;
        case CALTYPE_DANGI:
            year += 2333; break;
        case CALTYPE_ISLAMIC_CIVIL:
        case CALTYPE_ISLAMIC:
        case CALTYPE_ISLAMIC_UMALQURA:
        case CALTYPE_ISLAMIC_TBLA:
        case CALTYPE_ISLAMIC_RGSA:
            year = firstIslamicStartYearFromGrego(year); break;
        default:
            // CALTYPE_GREGORIAN
            // CALTYPE_JAPANESE
            // CALTYPE_BUDDHIST
            // CALTYPE_ROC
            // CALTYPE_ISO8601
            // do nothing, EXTENDED_YEAR same as Gregorian
            break;
    }
    // set extended year
    set(UCAL_EXTENDED_YEAR, year);
}

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

void
Calendar::clear()
{
    for (int32_t i=0; i<UCAL_FIELD_COUNT; ++i) {
        fFields[i]     = 0; // Must do this; other code depends on it
        fStamp[i]     = kUnset;
        fIsSet[i]     = FALSE; // Remove later
    }
    fIsTimeSet = fAreFieldsSet = fAreAllFieldsSet = fAreFieldsVirtuallySet = FALSE;
    // fTime is not 'cleared' - may be used if no fields are set.
}

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

void
Calendar::clear(UCalendarDateFields field)
{
    if (fAreFieldsVirtuallySet) {
        UErrorCode ec = U_ZERO_ERROR;
        computeFields(ec);
    }
    fFields[field]         = 0;
    fStamp[field]         = kUnset;
    fIsSet[field]         = FALSE; // Remove later
    fIsTimeSet = fAreFieldsSet = fAreAllFieldsSet = fAreFieldsVirtuallySet = FALSE;
}

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

UBool
Calendar::isSet(UCalendarDateFields field) const
{
    return fAreFieldsVirtuallySet || (fStamp[field] != kUnset);
}


int32_t Calendar::newestStamp(UCalendarDateFields first, UCalendarDateFields last, int32_t bestStampSoFar) const
{
    int32_t bestStamp = bestStampSoFar;
    for (int32_t i=(int32_t)first; i<=(int32_t)last; ++i) {
        if (fStamp[i] > bestStamp) {
            bestStamp = fStamp[i];
        }
    }
    return bestStamp;
}


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

void
Calendar::complete(UErrorCode& status)
{
    if (!fIsTimeSet) {
        updateTime(status);
        /* Test for buffer overflows */
        if(U_FAILURE(status)) {
            return;
        }
    }
    if (!fAreFieldsSet) {
        computeFields(status); // fills in unset fields
        /* Test for buffer overflows */
        if(U_FAILURE(status)) {
            return;
        }
        fAreFieldsSet         = TRUE;
        fAreAllFieldsSet     = TRUE;
    }
}

//-------------------------------------------------------------------------
// 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 #DAY_OF_MONTH 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.
*
* @see #getActualMinimum
* @see #getActualMaximum
* @stable ICU 2.0
*/
void Calendar::pinField(UCalendarDateFields field, UErrorCode& status) {
    int32_t max = getActualMaximum(field, status);
    int32_t min = getActualMinimum(field, status);

    if (fFields[field] > max) {
        set(field, max);
    } else if (fFields[field] < min) {
        set(field, min);
    }
}


void Calendar::computeFields(UErrorCode &ec)
{
  if (U_FAILURE(ec)) {
        return;
    }
    // Compute local wall millis
    double localMillis = internalGetTime();
    int32_t rawOffset, dstOffset;
    getTimeZone().getOffset(localMillis, FALSE, rawOffset, dstOffset, ec);
    localMillis += (rawOffset + dstOffset);

    // Mark fields as set.  Do this before calling handleComputeFields().
    uint32_t mask =   //fInternalSetMask;
        (1 << UCAL_ERA) |
        (1 << UCAL_YEAR) |
        (1 << UCAL_MONTH) |
        (1 << UCAL_DAY_OF_MONTH) | // = UCAL_DATE
        (1 << UCAL_DAY_OF_YEAR) |
        (1 << UCAL_EXTENDED_YEAR);

    for (int32_t i=0; i<UCAL_FIELD_COUNT; ++i) {
        if ((mask & 1) == 0) {
            fStamp[i] = kInternallySet;
            fIsSet[i] = TRUE; // Remove later
        } else {
            fStamp[i] = kUnset;
            fIsSet[i] = FALSE; // Remove later
        }
        mask >>= 1;
    }

    // We used to check for and correct extreme millis values (near
    // Long.MIN_VALUE or Long.MAX_VALUE) here.  Such values would cause
    // overflows from positive to negative (or vice versa) and had to
    // be manually tweaked.  We no longer need to do this because we
    // have limited the range of supported dates to those that have a
    // Julian day that fits into an int.  This allows us to implement a
    // JULIAN_DAY field and also removes some inelegant code. - Liu
    // 11/6/00

    int32_t days =  (int32_t)ClockMath::floorDivide(localMillis, (double)kOneDay);

    internalSet(UCAL_JULIAN_DAY,days + kEpochStartAsJulianDay);

#if defined (U_DEBUG_CAL)
    //fprintf(stderr, "%s:%d- Hmm! Jules @ %d, as per %.0lf millis\n",
    //__FILE__, __LINE__, fFields[UCAL_JULIAN_DAY], localMillis);
#endif

    computeGregorianAndDOWFields(fFields[UCAL_JULIAN_DAY], ec);

    // Call framework method to have subclass compute its fields.
    // These must include, at a minimum, MONTH, DAY_OF_MONTH,
    // EXTENDED_YEAR, YEAR, DAY_OF_YEAR.  This method will call internalSet(),
    // which will update stamp[].
    handleComputeFields(fFields[UCAL_JULIAN_DAY], ec);

    // Compute week-related fields, based on the subclass-computed
    // fields computed by handleComputeFields().
    computeWeekFields(ec);

    // Compute time-related fields.  These are indepent of the date and
    // of the subclass algorithm.  They depend only on the local zone
    // wall milliseconds in day.
    int32_t millisInDay =  (int32_t) (localMillis - (days * kOneDay));
    fFields[UCAL_MILLISECONDS_IN_DAY] = millisInDay;
    fFields[UCAL_MILLISECOND] = millisInDay % 1000;
    millisInDay /= 1000;
    fFields[UCAL_SECOND] = millisInDay % 60;
    millisInDay /= 60;
    fFields[UCAL_MINUTE] = millisInDay % 60;
    millisInDay /= 60;
    fFields[UCAL_HOUR_OF_DAY] = millisInDay;
    fFields[UCAL_AM_PM] = millisInDay / 12; // Assume AM == 0
    fFields[UCAL_HOUR] = millisInDay % 12;
    fFields[UCAL_ZONE_OFFSET] = rawOffset;
    fFields[UCAL_DST_OFFSET] = dstOffset;
}

uint8_t Calendar::julianDayToDayOfWeek(double julian)
{
    // If julian is negative, then julian%7 will be negative, so we adjust
    // accordingly.  We add 1 because Julian day 0 is Monday.
    int8_t dayOfWeek = (int8_t) uprv_fmod(julian + 1, 7);

    uint8_t result = (uint8_t)(dayOfWeek + ((dayOfWeek < 0) ? (7+UCAL_SUNDAY ) : UCAL_SUNDAY));
    return result;
}

/**
* Compute the Gregorian calendar year, month, and day of month from
* the given Julian day.  These values are not stored in fields, but in
* member variables gregorianXxx.  Also compute the DAY_OF_WEEK and
* DOW_LOCAL fields.
*/
void Calendar::computeGregorianAndDOWFields(int32_t julianDay, UErrorCode &ec)
{
    computeGregorianFields(julianDay, ec);

    // Compute day of week: JD 0 = Monday
    int32_t dow = julianDayToDayOfWeek(julianDay);
    internalSet(UCAL_DAY_OF_WEEK,dow);

    // Calculate 1-based localized day of week
    int32_t dowLocal = dow - getFirstDayOfWeek() + 1;
    if (dowLocal < 1) {
        dowLocal += 7;
    }
    internalSet(UCAL_DOW_LOCAL,dowLocal);
    fFields[UCAL_DOW_LOCAL] = dowLocal;
}

/**
* 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.
*/
void Calendar::computeGregorianFields(int32_t julianDay, UErrorCode & /* ec */) {
    int32_t gregorianDayOfWeekUnused;
    Grego::dayToFields(julianDay - kEpochStartAsJulianDay, fGregorianYear, fGregorianMonth, fGregorianDayOfMonth, gregorianDayOfWeekUnused, fGregorianDayOfYear);
}

/**
* 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 Calendar::computeWeekFields(UErrorCode &ec) {
    if(U_FAILURE(ec)) {
        return;
    }
    int32_t eyear = fFields[UCAL_EXTENDED_YEAR];
    int32_t dayOfWeek = fFields[UCAL_DAY_OF_WEEK];
    int32_t dayOfYear = fFields[UCAL_DAY_OF_YEAR];

    // WEEK_OF_YEAR start
    // Compute the week of the year.  For the Gregorian calendar, valid week
    // numbers run from 1 to 52 or 53, depending on the year, the first day
    // of the week, and the minimal days in the first week.  For other
    // calendars, the valid range may be different -- it depends on the year
    // length.  Days at the start of the year may fall into the last week of
    // the previous year; days at the end of the year may fall into the
    // first week of the next year.  ASSUME that the year length is less than
    // 7000 days.
    int32_t yearOfWeekOfYear = eyear;
    int32_t relDow = (dayOfWeek + 7 - getFirstDayOfWeek()) % 7; // 0..6
    int32_t relDowJan1 = (dayOfWeek - dayOfYear + 7001 - getFirstDayOfWeek()) % 7; // 0..6
    int32_t woy = (dayOfYear - 1 + relDowJan1) / 7; // 0..53
    if ((7 - relDowJan1) >= getMinimalDaysInFirstWeek()) {
        ++woy;
    }

    // Adjust for weeks at the year end that overlap into the previous or
    // next calendar year.
    if (woy == 0) {
        // We are the last week of the previous year.
        // Check to see if we are in the last week; if so, we need
        // to handle the case in which we are the first week of the
        // next year.

        int32_t prevDoy = dayOfYear + handleGetYearLength(eyear - 1);
        woy = weekNumber(prevDoy, dayOfWeek);
        yearOfWeekOfYear--;
    } else {
        int32_t lastDoy = handleGetYearLength(eyear);
        // Fast check: For it to be week 1 of the next year, the DOY
        // must be on or after L-5, where L is yearLength(), then it
        // cannot possibly be week 1 of the next year:
        //          L-5                  L
        // doy: 359 360 361 362 363 364 365 001
        // dow:      1   2   3   4   5   6   7
        if (dayOfYear >= (lastDoy - 5)) {
            int32_t lastRelDow = (relDow + lastDoy - dayOfYear) % 7;
            if (lastRelDow < 0) {
                lastRelDow += 7;
            }
            if (((6 - lastRelDow) >= getMinimalDaysInFirstWeek()) &&
                ((dayOfYear + 7 - relDow) > lastDoy)) {
                    woy = 1;
                    yearOfWeekOfYear++;
                }
        }
    }
    fFields[UCAL_WEEK_OF_YEAR] = woy;
    fFields[UCAL_YEAR_WOY] = yearOfWeekOfYear;
    // WEEK_OF_YEAR end

    int32_t dayOfMonth = fFields[UCAL_DAY_OF_MONTH];
    fFields[UCAL_WEEK_OF_MONTH] = weekNumber(dayOfMonth, dayOfWeek);
    fFields[UCAL_DAY_OF_WEEK_IN_MONTH] = (dayOfMonth-1) / 7 + 1;
#if defined (U_DEBUG_CAL)
    if(fFields[UCAL_DAY_OF_WEEK_IN_MONTH]==0) fprintf(stderr, "%s:%d: DOWIM %d on %g\n",
        __FILE__, __LINE__,fFields[UCAL_DAY_OF_WEEK_IN_MONTH], fTime);
#endif
}


int32_t Calendar::weekNumber(int32_t desiredDay, int32_t dayOfPeriod, int32_t dayOfWeek)
{
    // Determine the day of the week of the first day of the period
    // in question (either a year or a month).  Zero represents the
    // first day of the week on this calendar.
    int32_t periodStartDayOfWeek = (dayOfWeek - getFirstDayOfWeek() - dayOfPeriod + 1) % 7;
    if (periodStartDayOfWeek < 0) periodStartDayOfWeek += 7;

    // Compute the week number.  Initially, ignore the first week, which
    // may be fractional (or may not be).  We add periodStartDayOfWeek in
    // order to fill out the first week, if it is fractional.
    int32_t weekNo = (desiredDay + periodStartDayOfWeek - 1)/7;

    // If the first week is long enough, then count it.  If
    // the minimal days in the first week is one, or if the period start
    // is zero, we always increment weekNo.
    if ((7 - periodStartDayOfWeek) >= getMinimalDaysInFirstWeek()) ++weekNo;

    return weekNo;
}

void Calendar::handleComputeFields(int32_t /* julianDay */, UErrorCode &/* status */)
{
    internalSet(UCAL_MONTH, getGregorianMonth());
    internalSet(UCAL_DAY_OF_MONTH, getGregorianDayOfMonth());
    internalSet(UCAL_DAY_OF_YEAR, getGregorianDayOfYear());
    int32_t eyear = getGregorianYear();
    internalSet(UCAL_EXTENDED_YEAR, eyear);
    int32_t era = GregorianCalendar::AD;
    if (eyear < 1) {
        era = GregorianCalendar::BC;
        eyear = 1 - eyear;
    }
    internalSet(UCAL_ERA, era);
    internalSet(UCAL_YEAR, eyear);
}
// -------------------------------------


void Calendar::roll(EDateFields field, int32_t amount, UErrorCode& status)
{
    roll((UCalendarDateFields)field, amount, status);
}

void Calendar::roll(UCalendarDateFields field, int32_t amount, UErrorCode& status)
{
    if (amount == 0) {
        return; // Nothing to do
    }

    complete(status);

    if(U_FAILURE(status)) {
        return;
    }
    switch (field) {
    case UCAL_DAY_OF_MONTH:
    case UCAL_AM_PM:
    case UCAL_MINUTE:
    case UCAL_SECOND:
    case UCAL_MILLISECOND:
    case UCAL_MILLISECONDS_IN_DAY:
    case UCAL_ERA:
        // These are the standard roll instructions.  These work for all
        // simple cases, that is, cases in which the limits are fixed, such
        // as the hour, the day of the month, and the era.
        {
            int32_t min = getActualMinimum(field,status);
            int32_t max = getActualMaximum(field,status);
            int32_t gap = max - min + 1;

            int32_t value = internalGet(field) + amount;
            value = (value - min) % gap;
            if (value < 0) {
                value += gap;
            }
            value += min;

            set(field, value);
            return;
        }

    case UCAL_HOUR:
    case UCAL_HOUR_OF_DAY:
        // Rolling the hour is difficult on the ONSET and CEASE days of
        // daylight savings.  For example, if the change occurs at
        // 2 AM, we have the following progression:
        // ONSET: 12 Std -> 1 Std -> 3 Dst -> 4 Dst
        // CEASE: 12 Dst -> 1 Dst -> 1 Std -> 2 Std
        // To get around this problem we don't use fields; we manipulate
        // the time in millis directly.
        {
            // Assume min == 0 in calculations below
            double start = getTimeInMillis(status);
            int32_t oldHour = internalGet(field);
            int32_t max = getMaximum(field);
            int32_t newHour = (oldHour + amount) % (max + 1);
            if (newHour < 0) {
                newHour += max + 1;
            }
            setTimeInMillis(start + kOneHour * (newHour - oldHour),status);
            return;
        }

    case UCAL_MONTH:
        // Rolling the month involves both pinning the final value
        // and adjusting the DAY_OF_MONTH if necessary.  We only adjust the
        // DAY_OF_MONTH if, after updating the MONTH field, it is illegal.
        // E.g., <jan31>.roll(MONTH, 1) -> <feb28> or <feb29>.
        {
            int32_t max = getActualMaximum(UCAL_MONTH, status);
            int32_t mon = (internalGet(UCAL_MONTH) + amount) % (max+1);

            if (mon < 0) {
                mon += (max + 1);
            }
            set(UCAL_MONTH, mon);

            // Keep the day of month in range.  We don't want to spill over
            // into the next month; e.g., we don't want jan31 + 1 mo -> feb31 ->
            // mar3.
            pinField(UCAL_DAY_OF_MONTH,status);
            return;
        }

    case UCAL_YEAR:
    case UCAL_YEAR_WOY:
        {
            // * If era==0 and years go backwards in time, change sign of amount.
            // * Until we have new API per #9393, we temporarily hardcode knowledge of
            //   which calendars have era 0 years that go backwards.
            UBool era0WithYearsThatGoBackwards = FALSE;
            int32_t era = get(UCAL_ERA, status);
            if (era == 0) {
                const char * calType = getType();
                if ( uprv_strcmp(calType,"gregorian")==0 || uprv_strcmp(calType,"roc")==0 || uprv_strcmp(calType,"coptic")==0 ) {
                    amount = -amount;
                    era0WithYearsThatGoBackwards = TRUE;
                }
            }
            int32_t newYear = internalGet(field) + amount;
            if (era > 0 || newYear >= 1) {
                int32_t maxYear = getActualMaximum(field, status);
                if (maxYear < 32768) {
                    // this era has real bounds, roll should wrap years
                    if (newYear < 1) {
                        newYear = maxYear - ((-newYear) % maxYear);
                    } else if (newYear > maxYear) {
                        newYear = ((newYear - 1) % maxYear) + 1;
                    }
                // else era is unbounded, just pin low year instead of wrapping
                } else if (newYear < 1) {
                    newYear = 1;
                }
            // else we are in era 0 with newYear < 1;
            // calendars with years that go backwards must pin the year value at 0,
            // other calendars can have years < 0 in era 0
            } else if (era0WithYearsThatGoBackwards) {
                newYear = 1;
            }
            set(field, newYear);
            pinField(UCAL_MONTH,status);
            pinField(UCAL_DAY_OF_MONTH,status);
            return;
        }

    case UCAL_EXTENDED_YEAR:
        // Rolling the year can involve pinning the DAY_OF_MONTH.
        set(field, internalGet(field) + amount);
        pinField(UCAL_MONTH,status);
        pinField(UCAL_DAY_OF_MONTH,status);
        return;

    case UCAL_WEEK_OF_MONTH:
        {
            // This is tricky, because during the roll we may have to shift
            // to a different day of the week.  For example:

            //    s  m  t  w  r  f  s
            //          1  2  3  4  5
            //    6  7  8  9 10 11 12

            // When rolling from the 6th or 7th back one week, we go to the
            // 1st (assuming that the first partial week counts).  The same
            // thing happens at the end of the month.

            // The other tricky thing is that we have to figure out whether
            // the first partial week actually counts or not, based on the
            // minimal first days in the week.  And we have to use the
            // correct first day of the week to delineate the week
            // boundaries.

            // Here's our algorithm.  First, we find the real boundaries of
            // the month.  Then we discard the first partial week if it
            // doesn't count in this locale.  Then we fill in the ends with
            // phantom days, so that the first partial week and the last
            // partial week are full weeks.  We then have a nice square
            // block of weeks.  We do the usual rolling within this block,
            // as is done elsewhere in this method.  If we wind up on one of
            // the phantom days that we added, we recognize this and pin to
            // the first or the last day of the month.  Easy, eh?

            // Normalize the DAY_OF_WEEK so that 0 is the first day of the week
            // in this locale.  We have dow in 0..6.
            int32_t dow = internalGet(UCAL_DAY_OF_WEEK) - getFirstDayOfWeek();
            if (dow < 0) dow += 7;

            // Find the day of the week (normalized for locale) for the first
            // of the month.
            int32_t fdm = (dow - internalGet(UCAL_DAY_OF_MONTH) + 1) % 7;
            if (fdm < 0) fdm += 7;

            // Get the first day of the first full week of the month,
            // including phantom days, if any.  Figure out if the first week
            // counts or not; if it counts, then fill in phantom days.  If
            // not, advance to the first real full week (skip the partial week).
            int32_t start;
            if ((7 - fdm) < getMinimalDaysInFirstWeek())
                start = 8 - fdm; // Skip the first partial week
            else
                start = 1 - fdm; // This may be zero or negative

            // Get the day of the week (normalized for locale) for the last
            // day of the month.
            int32_t monthLen = getActualMaximum(UCAL_DAY_OF_MONTH, status);
            int32_t ldm = (monthLen - internalGet(UCAL_DAY_OF_MONTH) + dow) % 7;
            // We know monthLen >= DAY_OF_MONTH so we skip the += 7 step here.

            // Get the limit day for the blocked-off rectangular month; that
            // is, the day which is one past the last day of the month,
            // after the month has already been filled in with phantom days
            // to fill out the last week.  This day has a normalized DOW of 0.
            int32_t limit = monthLen + 7 - ldm;

            // Now roll between start and (limit - 1).
            int32_t gap = limit - start;
            int32_t day_of_month = (internalGet(UCAL_DAY_OF_MONTH) + amount*7 -
                start) % gap;
            if (day_of_month < 0) day_of_month += gap;
            day_of_month += start;

            // Finally, pin to the real start and end of the month.
            if (day_of_month < 1) day_of_month = 1;
            if (day_of_month > monthLen) day_of_month = monthLen;

            // Set the DAY_OF_MONTH.  We rely on the fact that this field
            // takes precedence over everything else (since all other fields
            // are also set at this point).  If this fact changes (if the
            // disambiguation algorithm changes) then we will have to unset
            // the appropriate fields here so that DAY_OF_MONTH is attended
            // to.
            set(UCAL_DAY_OF_MONTH, day_of_month);
            return;
        }
    case UCAL_WEEK_OF_YEAR:
        {
            // This follows the outline of WEEK_OF_MONTH, except it applies
            // to the whole year.  Please see the comment for WEEK_OF_MONTH
            // for general notes.

            // Normalize the DAY_OF_WEEK so that 0 is the first day of the week
            // in this locale.  We have dow in 0..6.
            int32_t dow = internalGet(UCAL_DAY_OF_WEEK) - getFirstDayOfWeek();
            if (dow < 0) dow += 7;

            // Find the day of the week (normalized for locale) for the first
            // of the year.
            int32_t fdy = (dow - internalGet(UCAL_DAY_OF_YEAR) + 1) % 7;
            if (fdy < 0) fdy += 7;

            // Get the first day of the first full week of the year,
            // including phantom days, if any.  Figure out if the first week
            // counts or not; if it counts, then fill in phantom days.  If
            // not, advance to the first real full week (skip the partial week).
            int32_t start;
            if ((7 - fdy) < getMinimalDaysInFirstWeek())
                start = 8 - fdy; // Skip the first partial week
            else
                start = 1 - fdy; // This may be zero or negative

            // Get the day of the week (normalized for locale) for the last
            // day of the year.
            int32_t yearLen = getActualMaximum(UCAL_DAY_OF_YEAR,status);
            int32_t ldy = (yearLen - internalGet(UCAL_DAY_OF_YEAR) + dow) % 7;
            // We know yearLen >= DAY_OF_YEAR so we skip the += 7 step here.

            // Get the limit day for the blocked-off rectangular year; that
            // is, the day which is one past the last day of the year,
            // after the year has already been filled in with phantom days
            // to fill out the last week.  This day has a normalized DOW of 0.
            int32_t limit = yearLen + 7 - ldy;

            // Now roll between start and (limit - 1).
            int32_t gap = limit - start;
            int32_t day_of_year = (internalGet(UCAL_DAY_OF_YEAR) + amount*7 -
                start) % gap;
            if (day_of_year < 0) day_of_year += gap;
            day_of_year += start;

            // Finally, pin to the real start and end of the month.
            if (day_of_year < 1) day_of_year = 1;
            if (day_of_year > yearLen) day_of_year = yearLen;

            // Make sure that the year and day of year are attended to by
            // clearing other fields which would normally take precedence.
            // If the disambiguation algorithm is changed, this section will
            // have to be updated as well.
            set(UCAL_DAY_OF_YEAR, day_of_year);
            clear(UCAL_MONTH);
            return;
        }
    case UCAL_DAY_OF_YEAR:
        {
            // Roll the day of year using millis.  Compute the millis for
            // the start of the year, and get the length of the year.
            double delta = amount * kOneDay; // Scale up from days to millis
            double min2 = internalGet(UCAL_DAY_OF_YEAR)-1;
            min2 *= kOneDay;
            min2 = internalGetTime() - min2;

            //      double min2 = internalGetTime() - (internalGet(UCAL_DAY_OF_YEAR) - 1.0) * kOneDay;
            double newtime;

            double yearLength = getActualMaximum(UCAL_DAY_OF_YEAR,status);
            double oneYear = yearLength;
            oneYear *= kOneDay;
            newtime = uprv_fmod((internalGetTime() + delta - min2), oneYear);
            if (newtime < 0) newtime += oneYear;
            setTimeInMillis(newtime + min2, status);
            return;
        }
    case UCAL_DAY_OF_WEEK:
    case UCAL_DOW_LOCAL:
        {
            // Roll the day of week using millis.  Compute the millis for
            // the start of the week, using the first day of week setting.
            // Restrict the millis to [start, start+7days).
            double delta = amount * kOneDay; // Scale up from days to millis
            // Compute the number of days before the current day in this
            // week.  This will be a value 0..6.
            int32_t leadDays = internalGet(field);
            leadDays -= (field == UCAL_DAY_OF_WEEK) ? getFirstDayOfWeek() : 1;
            if (leadDays < 0) leadDays += 7;
            double min2 = internalGetTime() - leadDays * kOneDay;
            double newtime = uprv_fmod((internalGetTime() + delta - min2), kOneWeek);
            if (newtime < 0) newtime += kOneWeek;
            setTimeInMillis(newtime + min2, status);
            return;
        }
    case UCAL_DAY_OF_WEEK_IN_MONTH:
        {
            // Roll the day of week in the month using millis.  Determine
            // the first day of the week in the month, and then the last,
            // and then roll within that range.
            double delta = amount * kOneWeek; // Scale up from weeks to millis
            // Find the number of same days of the week before this one
            // in this month.
            int32_t preWeeks = (internalGet(UCAL_DAY_OF_MONTH) - 1) / 7;
            // Find the number of same days of the week after this one
            // in this month.
            int32_t postWeeks = (getActualMaximum(UCAL_DAY_OF_MONTH,status) -
                internalGet(UCAL_DAY_OF_MONTH)) / 7;
            // From these compute the min and gap millis for rolling.
            double min2 = internalGetTime() - preWeeks * kOneWeek;
            double gap2 = kOneWeek * (preWeeks + postWeeks + 1); // Must add 1!
            // Roll within this range
            double newtime = uprv_fmod((internalGetTime() + delta - min2), gap2);
            if (newtime < 0) newtime += gap2;
            setTimeInMillis(newtime + min2, status);
            return;
        }
    case UCAL_JULIAN_DAY:
        set(field, internalGet(field) + amount);
        return;
    default:
        // Other fields cannot be rolled by this method
#if defined (U_DEBUG_CAL)
        fprintf(stderr, "%s:%d: ILLEGAL ARG because of roll on non-rollable field %s\n",
            __FILE__, __LINE__,fldName(field));
#endif
        status = U_ILLEGAL_ARGUMENT_ERROR;
    }
}

void Calendar::add(EDateFields field, int32_t amount, UErrorCode& status)
{
    Calendar::add((UCalendarDateFields)field, amount, status);
}

// -------------------------------------
void Calendar::add(UCalendarDateFields field, int32_t amount, UErrorCode& status)
{
    if (amount == 0) {
        return;   // Do nothing!
    }

    // We handle most fields in the same way.  The algorithm is to add
    // a computed amount of millis to the current millis.  The only
    // wrinkle is with DST (and/or a change to the zone's UTC offset, which
    // we'll include with DST) -- for some fields, like the DAY_OF_MONTH,
    // we don't want the wall time to shift due to changes in DST.  If the
    // result of the add operation is to move from DST to Standard, or
    // vice versa, we need to adjust by an hour forward or back,
    // respectively.  For such fields we set keepWallTimeInvariant to TRUE.

    // We only adjust the DST for fields larger than an hour.  For
    // fields smaller than an hour, we cannot adjust for DST without
    // causing problems.  for instance, if you add one hour to April 5,
    // 1998, 1:00 AM, in PST, the time becomes "2:00 AM PDT" (an
    // illegal value), but then the adjustment sees the change and
    // compensates by subtracting an hour.  As a result the time
    // doesn't advance at all.

    // For some fields larger than a day, such as a UCAL_MONTH, we pin the
    // UCAL_DAY_OF_MONTH.  This allows <March 31>.add(UCAL_MONTH, 1) to be
    // <April 30>, rather than <April 31> => <May 1>.

    double delta = amount; // delta in ms
    UBool keepWallTimeInvariant = TRUE;

    switch (field) {
    case UCAL_ERA:
        set(field, get(field, status) + amount);
        pinField(UCAL_ERA, status);
        return;

    case UCAL_YEAR:
    case UCAL_YEAR_WOY:
      {
        // * If era=0 and years go backwards in time, change sign of amount.
        // * Until we have new API per #9393, we temporarily hardcode knowledge of
        //   which calendars have era 0 years that go backwards.
        // * Note that for UCAL_YEAR (but not UCAL_YEAR_WOY) we could instead handle
        //   this by applying the amount to the UCAL_EXTENDED_YEAR field; but since
        //   we would still need to handle UCAL_YEAR_WOY as below, might as well
        //   also handle UCAL_YEAR the same way.
        int32_t era = get(UCAL_ERA, status);
        if (era == 0) {
          const char * calType = getType();
          if ( uprv_strcmp(calType,"gregorian")==0 || uprv_strcmp(calType,"roc")==0 || uprv_strcmp(calType,"coptic")==0 ) {
            amount = -amount;
          }
        }
      }
      // Fall through into normal handling
    case UCAL_EXTENDED_YEAR:
    case UCAL_MONTH:
      {
        UBool oldLenient = isLenient();
        setLenient(TRUE);
        set(field, get(field, status) + amount);
        pinField(UCAL_DAY_OF_MONTH, status);
        if(oldLenient==FALSE) {
          complete(status); /* force recalculate */
          setLenient(oldLenient);
        }
      }
      return;

    case UCAL_WEEK_OF_YEAR:
    case UCAL_WEEK_OF_MONTH:
    case UCAL_DAY_OF_WEEK_IN_MONTH:
        delta *= kOneWeek;
        break;

    case UCAL_AM_PM:
        delta *= 12 * kOneHour;
        break;

    case UCAL_DAY_OF_MONTH:
    case UCAL_DAY_OF_YEAR:
    case UCAL_DAY_OF_WEEK:
    case UCAL_DOW_LOCAL:
    case UCAL_JULIAN_DAY:
        delta *= kOneDay;
        break;

    case UCAL_HOUR_OF_DAY:
    case UCAL_HOUR:
        delta *= kOneHour;
        keepWallTimeInvariant = FALSE;
        break;

    case UCAL_MINUTE:
        delta *= kOneMinute;
        keepWallTimeInvariant = FALSE;
        break;

    case UCAL_SECOND:
        delta *= kOneSecond;
        keepWallTimeInvariant = FALSE;
        break;

    case UCAL_MILLISECOND:
    case UCAL_MILLISECONDS_IN_DAY:
        keepWallTimeInvariant = FALSE;
        break;

    default:
#if defined (U_DEBUG_CAL)
        fprintf(stderr, "%s:%d: ILLEGAL ARG because field %s not addable",
            __FILE__, __LINE__, fldName(field));
#endif
        status = U_ILLEGAL_ARGUMENT_ERROR;
        return;
        //  throw new IllegalArgumentException("Calendar.add(" + fieldName(field) +
        //                                     ") not supported");
    }

    // In order to keep the wall time invariant (for fields where this is
    // appropriate), check the combined DST & ZONE offset before and
    // after the add() operation. If it changes, then adjust the millis
    // to compensate.
    int32_t prevOffset = 0;
    int32_t prevWallTime = 0;
    if (keepWallTimeInvariant) {
        prevOffset = get(UCAL_DST_OFFSET, status) + get(UCAL_ZONE_OFFSET, status);
        prevWallTime = get(UCAL_MILLISECONDS_IN_DAY, status);
    }

    setTimeInMillis(getTimeInMillis(status) + delta, status);

    if (keepWallTimeInvariant) {
        int32_t newWallTime = get(UCAL_MILLISECONDS_IN_DAY, status);
        if (newWallTime != prevWallTime) {
            // There is at least one zone transition between the base
            // time and the result time. As the result, wall time has
            // changed.
            UDate t = internalGetTime();
            int32_t newOffset = get(UCAL_DST_OFFSET, status) + get(UCAL_ZONE_OFFSET, status);
            if (newOffset != prevOffset) {
                // When the difference of the previous UTC offset and
                // the new UTC offset exceeds 1 full day, we do not want
                // to roll over/back the date. For now, this only happens
                // in Samoa (Pacific/Apia) on Dec 30, 2011. See ticket:9452.
                int32_t adjAmount = prevOffset - newOffset;
                adjAmount = adjAmount >= 0 ? adjAmount % (int32_t)kOneDay : -(-adjAmount % (int32_t)kOneDay);
                if (adjAmount != 0) {
                    setTimeInMillis(t + adjAmount, status);
                    newWallTime = get(UCAL_MILLISECONDS_IN_DAY, status);
                }
                if (newWallTime != prevWallTime) {
                    // The result wall time or adjusted wall time was shifted because
                    // the target wall time does not exist on the result date.
                    switch (fSkippedWallTime) {
                    case UCAL_WALLTIME_FIRST:
                        if (adjAmount > 0) {
                            setTimeInMillis(t, status);
                        }
                        break;
                    case UCAL_WALLTIME_LAST:
                        if (adjAmount < 0) {
                            setTimeInMillis(t, status);
                        }
                        break;
                    case UCAL_WALLTIME_NEXT_VALID:
                        UDate tmpT = adjAmount > 0 ? internalGetTime() : t;
                        UDate immediatePrevTrans;
                        UBool hasTransition = getImmediatePreviousZoneTransition(tmpT, &immediatePrevTrans, status);
                        if (U_SUCCESS(status) && hasTransition) {
                            setTimeInMillis(immediatePrevTrans, status);
                        }
                        break;
                    }
                }
            }
        }
    }
}

// -------------------------------------
int32_t Calendar::fieldDifference(UDate when, EDateFields field, UErrorCode& status) {
    return fieldDifference(when, (UCalendarDateFields) field, status);
}

int32_t Calendar::fieldDifference(UDate targetMs, UCalendarDateFields field, UErrorCode& ec) {
    if (U_FAILURE(ec)) return 0;
    int32_t min = 0;
    double startMs = getTimeInMillis(ec);
    // Always add from the start millis.  This accomodates
    // operations like adding years from February 29, 2000 up to
    // February 29, 2004.  If 1, 1, 1, 1 is added to the year
    // field, the DOM gets pinned to 28 and stays there, giving an
    // incorrect DOM difference of 1.  We have to add 1, reset, 2,
    // reset, 3, reset, 4.
    if (startMs < targetMs) {
        int32_t max = 1;
        // Find a value that is too large
        while (U_SUCCESS(ec)) {
            setTimeInMillis(startMs, ec);
            add(field, max, ec);
            double ms = getTimeInMillis(ec);
            if (ms == targetMs) {
                return max;
            } else if (ms > targetMs) {
                break;
            } else if (max < INT32_MAX) {
                min = max;
                max <<= 1;
                if (max < 0) {
                    max = INT32_MAX;
                }
            } else {
                // Field difference too large to fit into int32_t
#if defined (U_DEBUG_CAL)
                fprintf(stderr, "%s:%d: ILLEGAL ARG because field %s's max too large for int32_t\n",
                    __FILE__, __LINE__, fldName(field));
#endif
                ec = U_ILLEGAL_ARGUMENT_ERROR;
            }
        }
        // Do a binary search
        while ((max - min) > 1 && U_SUCCESS(ec)) {
            int32_t t = min + (max - min)/2; // make sure intermediate values don't exceed INT32_MAX
            setTimeInMillis(startMs, ec);
            add(field, t, ec);
            double ms = getTimeInMillis(ec);
            if (ms == targetMs) {
                return t;
            } else if (ms > targetMs) {
                max = t;
            } else {
                min = t;
            }
        }
    } else if (startMs > targetMs) {
        int32_t max = -1;
        // Find a value that is too small
        while (U_SUCCESS(ec)) {
            setTimeInMillis(startMs, ec);
            add(field, max, ec);
            double ms = getTimeInMillis(ec);
            if (ms == targetMs) {
                return max;
            } else if (ms < targetMs) {
                break;
            } else {
                min = max;
                max <<= 1;
                if (max == 0) {
                    // Field difference too large to fit into int32_t
#if defined (U_DEBUG_CAL)
                    fprintf(stderr, "%s:%d: ILLEGAL ARG because field %s's max too large for int32_t\n",
                        __FILE__, __LINE__, fldName(field));
#endif
                    ec = U_ILLEGAL_ARGUMENT_ERROR;
                }
            }
        }
        // Do a binary search
        while ((min - max) > 1 && U_SUCCESS(ec)) {
            int32_t t = min + (max - min)/2; // make sure intermediate values don't exceed INT32_MAX
            setTimeInMillis(startMs, ec);
            add(field, t, ec);
            double ms = getTimeInMillis(ec);
            if (ms == targetMs) {
                return t;
            } else if (ms < targetMs) {
                max = t;
            } else {
                min = t;
            }
        }
    }
    // Set calendar to end point
    setTimeInMillis(startMs, ec);
    add(field, min, ec);

    /* Test for buffer overflows */
    if(U_FAILURE(ec)) {
        return 0;
    }
    return min;
}

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

void
Calendar::adoptTimeZone(TimeZone* zone)
{
    // Do nothing if passed-in zone is NULL
    if (zone == NULL) return;

    // fZone should always be non-null
    delete fZone;
    fZone = zone;

    // if the zone changes, we need to recompute the time fields
    fAreFieldsSet = FALSE;
}

// -------------------------------------
void
Calendar::setTimeZone(const TimeZone& zone)
{
    adoptTimeZone(zone.clone());
}

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

const TimeZone&
Calendar::getTimeZone() const
{
    U_ASSERT(fZone != NULL);
    return *fZone;
}

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

TimeZone*
Calendar::orphanTimeZone()
{
    // we let go of the time zone; the new time zone is the system default time zone
    TimeZone *defaultZone = TimeZone::createDefault();
    if (defaultZone == NULL) {
        // No error handling available. Must keep fZone non-NULL, there are many unchecked uses.
        return NULL;
    }
    TimeZone *z = fZone;
    fZone = defaultZone;
    return z;
}

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

void
Calendar::setLenient(UBool lenient)
{
    fLenient = lenient;
}

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

UBool
Calendar::isLenient() const
{
    return fLenient;
}

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

void
Calendar::setRepeatedWallTimeOption(UCalendarWallTimeOption option)
{
    if (option == UCAL_WALLTIME_LAST || option == UCAL_WALLTIME_FIRST) {
        fRepeatedWallTime = option;
    }
}

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

UCalendarWallTimeOption
Calendar::getRepeatedWallTimeOption(void) const
{
    return fRepeatedWallTime;
}

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

void
Calendar::setSkippedWallTimeOption(UCalendarWallTimeOption option)
{
    fSkippedWallTime = option;
}

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

UCalendarWallTimeOption
Calendar::getSkippedWallTimeOption(void) const
{
    return fSkippedWallTime;
}

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

void
Calendar::setFirstDayOfWeek(UCalendarDaysOfWeek value)
{
    if (fFirstDayOfWeek != value &&
        value >= UCAL_SUNDAY && value <= UCAL_SATURDAY) {
            fFirstDayOfWeek = value;
            fAreFieldsSet = FALSE;
        }
}

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

Calendar::EDaysOfWeek
Calendar::getFirstDayOfWeek() const
{
    return (Calendar::EDaysOfWeek)fFirstDayOfWeek;
}

UCalendarDaysOfWeek
Calendar::getFirstDayOfWeek(UErrorCode & /*status*/) const
{
    return fFirstDayOfWeek;
}
// -------------------------------------

void
Calendar::setMinimalDaysInFirstWeek(uint8_t value)
{
    // Values less than 1 have the same effect as 1; values greater
    // than 7 have the same effect as 7. However, we normalize values
    // so operator== and so forth work.
    if (value < 1) {
        value = 1;
    } else if (value > 7) {
        value = 7;
    }
    if (fMinimalDaysInFirstWeek != value) {
        fMinimalDaysInFirstWeek = value;
        fAreFieldsSet = FALSE;
    }
}

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

uint8_t
Calendar::getMinimalDaysInFirstWeek() const
{
    return fMinimalDaysInFirstWeek;
}

// -------------------------------------
// weekend functions, just dummy implementations for now (for API freeze)

UCalendarWeekdayType
Calendar::getDayOfWeekType(UCalendarDaysOfWeek dayOfWeek, UErrorCode &status) const
{
    if (U_FAILURE(status)) {
        return UCAL_WEEKDAY;
    }
    if (dayOfWeek < UCAL_SUNDAY || dayOfWeek > UCAL_SATURDAY) {
        status = U_ILLEGAL_ARGUMENT_ERROR;
        return UCAL_WEEKDAY;
    }
    if (fWeekendOnset == fWeekendCease) {
        if (dayOfWeek != fWeekendOnset)
            return UCAL_WEEKDAY;
        return (fWeekendOnsetMillis == 0) ? UCAL_WEEKEND : UCAL_WEEKEND_ONSET;
    }
    if (fWeekendOnset < fWeekendCease) {
        if (dayOfWeek < fWeekendOnset || dayOfWeek > fWeekendCease) {
            return UCAL_WEEKDAY;
        }
    } else {
        if (dayOfWeek > fWeekendCease && dayOfWeek < fWeekendOnset) {
            return UCAL_WEEKDAY;
        }
    }
    if (dayOfWeek == fWeekendOnset) {
        return (fWeekendOnsetMillis == 0) ? UCAL_WEEKEND : UCAL_WEEKEND_ONSET;
    }
    if (dayOfWeek == fWeekendCease) {
        return (fWeekendCeaseMillis >= 86400000) ? UCAL_WEEKEND : UCAL_WEEKEND_CEASE;
    }
    return UCAL_WEEKEND;
}

int32_t
Calendar::getWeekendTransition(UCalendarDaysOfWeek dayOfWeek, UErrorCode &status) const
{
    if (U_FAILURE(status)) {
        return 0;
    }
    if (dayOfWeek == fWeekendOnset) {
        return fWeekendOnsetMillis;
    } else if (dayOfWeek == fWeekendCease) {
        return fWeekendCeaseMillis;
    }
    status = U_ILLEGAL_ARGUMENT_ERROR;
    return 0;
}

UBool
Calendar::isWeekend(UDate date, UErrorCode &status) const
{
    if (U_FAILURE(status)) {
        return FALSE;
    }
    // clone the calendar so we don't mess with the real one.
    Calendar *work = (Calendar*)this->clone();
    if (work == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return FALSE;
    }
    UBool result = FALSE;
    work->setTime(date, status);
    if (U_SUCCESS(status)) {
        result = work->isWeekend();
    }
    delete work;
    return result;
}

UBool
Calendar::isWeekend(void) const
{
    UErrorCode status = U_ZERO_ERROR;
    UCalendarDaysOfWeek dayOfWeek = (UCalendarDaysOfWeek)get(UCAL_DAY_OF_WEEK, status);
    UCalendarWeekdayType dayType = getDayOfWeekType(dayOfWeek, status);
    if (U_SUCCESS(status)) {
        switch (dayType) {
            case UCAL_WEEKDAY:
                return FALSE;
            case UCAL_WEEKEND:
                return TRUE;
            case UCAL_WEEKEND_ONSET:
            case UCAL_WEEKEND_CEASE:
                // Use internalGet() because the above call to get() populated all fields.
                {
                    int32_t millisInDay = internalGet(UCAL_MILLISECONDS_IN_DAY);
                    int32_t transitionMillis = getWeekendTransition(dayOfWeek, status);
                    if (U_SUCCESS(status)) {
                        return (dayType == UCAL_WEEKEND_ONSET)?
                            (millisInDay >= transitionMillis):
                            (millisInDay <  transitionMillis);
                    }
                    // else fall through, return FALSE
                }
            default:
                break;
        }
    }
    return FALSE;
}

// ------------------------------------- limits

int32_t
Calendar::getMinimum(EDateFields field) const {
    return getLimit((UCalendarDateFields) field,UCAL_LIMIT_MINIMUM);
}

int32_t
Calendar::getMinimum(UCalendarDateFields field) const
{
    return getLimit(field,UCAL_LIMIT_MINIMUM);
}

// -------------------------------------
int32_t
Calendar::getMaximum(EDateFields field) const
{
    return getLimit((UCalendarDateFields) field,UCAL_LIMIT_MAXIMUM);
}

int32_t
Calendar::getMaximum(UCalendarDateFields field) const
{
    return getLimit(field,UCAL_LIMIT_MAXIMUM);
}

// -------------------------------------
int32_t
Calendar::getGreatestMinimum(EDateFields field) const
{
    return getLimit((UCalendarDateFields)field,UCAL_LIMIT_GREATEST_MINIMUM);
}

int32_t
Calendar::getGreatestMinimum(UCalendarDateFields field) const
{
    return getLimit(field,UCAL_LIMIT_GREATEST_MINIMUM);
}

// -------------------------------------
int32_t
Calendar::getLeastMaximum(EDateFields field) const
{
    return getLimit((UCalendarDateFields) field,UCAL_LIMIT_LEAST_MAXIMUM);
}

int32_t
Calendar::getLeastMaximum(UCalendarDateFields field) const
{
    return getLimit( field,UCAL_LIMIT_LEAST_MAXIMUM);
}

// -------------------------------------
int32_t
Calendar::getActualMinimum(EDateFields field, UErrorCode& status) const
{
    return getActualMinimum((UCalendarDateFields) field, status);
}

int32_t Calendar::getLimit(UCalendarDateFields field, ELimitType limitType) const {
    switch (field) {
    case UCAL_DAY_OF_WEEK:
    case UCAL_AM_PM:
    case UCAL_HOUR:
    case UCAL_HOUR_OF_DAY:
    case UCAL_MINUTE:
    case UCAL_SECOND:
    case UCAL_MILLISECOND:
    case UCAL_ZONE_OFFSET:
    case UCAL_DST_OFFSET:
    case UCAL_DOW_LOCAL:
    case UCAL_JULIAN_DAY:
    case UCAL_MILLISECONDS_IN_DAY:
    case UCAL_IS_LEAP_MONTH:
        return kCalendarLimits[field][limitType];

    case UCAL_WEEK_OF_MONTH:
        {
            int32_t limit;
            if (limitType == UCAL_LIMIT_MINIMUM) {
                limit = getMinimalDaysInFirstWeek() == 1 ? 1 : 0;
            } else if (limitType == UCAL_LIMIT_GREATEST_MINIMUM) {
                limit = 1;
            } else {
                int32_t minDaysInFirst = getMinimalDaysInFirstWeek();
                int32_t daysInMonth = handleGetLimit(UCAL_DAY_OF_MONTH, limitType);
                if (limitType == UCAL_LIMIT_LEAST_MAXIMUM) {
                    limit = (daysInMonth + (7 - minDaysInFirst)) / 7;
                } else { // limitType == UCAL_LIMIT_MAXIMUM
                    limit = (daysInMonth + 6 + (7 - minDaysInFirst)) / 7;
                }
            }
            return limit;
        }
    default:
        return handleGetLimit(field, limitType);
    }
}


int32_t
Calendar::getActualMinimum(UCalendarDateFields field, UErrorCode& status) const
{
    int32_t fieldValue = getGreatestMinimum(field);
    int32_t endValue = getMinimum(field);

    // if we know that the minimum value is always the same, just return it
    if (fieldValue == endValue) {
        return fieldValue;
    }

    // clone the calendar so we don't mess with the real one, and set it to
    // accept anything for the field values
    Calendar *work = (Calendar*)this->clone();
    if (work == NULL) {
        status = U_MEMORY_ALLOCATION_ERROR;
        return 0;
    }
    work->setLenient(TRUE);

    // now try each value from getLeastMaximum() to getMaximum() one by one until
    // we get a value that normalizes to another value.  The last value that
    // normalizes to itself is the actual minimum for the current date
    int32_t result = fieldValue;

    do {
        work->set(field, fieldValue);
        if (work->get(field, status) != fieldValue) {
            break;
        }
        else {
            result = fieldValue;
            fieldValue--;
        }
    } while (fieldValue >= endValue);

    delete work;

    /* Test for buffer overflows */
    if(U_FAILURE(status)) {
        return 0;
    }
    return result;
}

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



/**
* Ensure that each field is within its valid range by calling {@link
* #validateField(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)
*/
void Calendar::validateFields(UErrorCode &status) {
    for (int32_t field = 0; U_SUCCESS(status) && (field < UCAL_FIELD_COUNT); field++) {
        if (fStamp[field] >= kMinimumUserStamp) {
            validateField((UCalendarDateFields)field, 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
* <code>Calendar.validateField()</code>.
* @see #validateField(int, int, int)
*/
void Calendar::validateField(UCalendarDateFields field, UErrorCode &status) {
    int32_t y;
    switch (field) {
    case UCAL_DAY_OF_MONTH:
        y = handleGetExtendedYear();
        validateField(field, 1, handleGetMonthLength(y, internalGet(UCAL_MONTH)), status);
        break;
    case UCAL_DAY_OF_YEAR:
        y = handleGetExtendedYear();
        validateField(field, 1, handleGetYearLength(y), status);
        break;
    case UCAL_DAY_OF_WEEK_IN_MONTH:
        if (internalGet(field) == 0) {
#if defined (U_DEBUG_CAL)
            fprintf(stderr, "%s:%d: ILLEGAL ARG because DOW in month cannot be 0\n",
                __FILE__, __LINE__);
#endif
            status = U_ILLEGAL_ARGUMENT_ERROR; // "DAY_OF_WEEK_IN_MONTH cannot be zero"
            return;
        }
        validateField(field, getMinimum(field), getMaximum(field), status);
        break;
    default:
        validateField(field, getMinimum(field), getMaximum(field), status);
        break;
    }
}

/**
* Validate a single field of this calendar given its minimum and
* maximum allowed value.  If the field is out of range, throw a
* descriptive <code>IllegalArgumentException</code>.  Subclasses may
* use this method in their implementation of {@link
* #validateField(int)}.
*/
void Calendar::validateField(UCalendarDateFields field, int32_t min, int32_t max, UErrorCode& status)
{
    int32_t value = fFields[field];
    if (value < min || value > max) {
#if defined (U_DEBUG_CAL)
        fprintf(stderr, "%s:%d: ILLEGAL ARG because of field %s out of range %d..%d  at %d\n",
            __FILE__, __LINE__,fldName(field),min,max,value);
#endif
        status = U_ILLEGAL_ARGUMENT_ERROR;
        return;
    }
}

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

const UFieldResolutionTable* Calendar::getFieldResolutionTable() const {
    return kDatePrecedence;
}


UCalendarDateFields Calendar::newerField(UCalendarDateFields defaultField, UCalendarDateFields alternateField) const
{
    if (fStamp[alternateField] > fStamp[defaultField]) {
        return alternateField;
    }
    return defaultField;
}

UCalendarDateFields Calendar::resolveFields(const UFieldResolutionTable* precedenceTable) {
    int32_t bestField = UCAL_FIELD_COUNT;
    int32_t tempBestField;
    for (int32_t g=0; precedenceTable[g][0][0] != -1 && (bestField == UCAL_FIELD_COUNT); ++g) {
        int32_t bestStamp = kUnset;
        for (int32_t l=0; precedenceTable[g][l][0] != -1; ++l) {
            int32_t lineStamp = kUnset;
            // Skip over first entry if it is negative
            for (int32_t i=((precedenceTable[g][l][0]>=kResolveRemap)?1:0); precedenceTable[g][l][i]!=-1; ++i) {
                U_ASSERT(precedenceTable[g][l][i] < UCAL_FIELD_COUNT);
                int32_t s = fStamp[precedenceTable[g][l][i]];
                // If any field is unset then don't use this line
                if (s == kUnset) {
                    goto linesInGroup;
                } else if(s > lineStamp) {
                    lineStamp = s;
                }
            }
            // Record new maximum stamp & field no.
            if (lineStamp > bestStamp) {
                tempBestField = precedenceTable[g][l][0]; // First field refers to entire line
                if (tempBestField >= kResolveRemap) {
                    tempBestField &= (kResolveRemap-1);
                    // This check is needed to resolve some issues with UCAL_YEAR precedence mapping
                    if (tempBestField != UCAL_DATE || (fStamp[UCAL_WEEK_OF_MONTH] < fStamp[tempBestField])) {
                        bestField = tempBestField;
                    }
                } else {
                    bestField = tempBestField;
                }

                if (bestField == tempBestField) {
                    bestStamp = lineStamp;
                }
            }
linesInGroup:
            ;
        }
    }
    return (UCalendarDateFields)bestField;
}

const UFieldResolutionTable Calendar::kDatePrecedence[] =
{
    {
        { UCAL_DAY_OF_MONTH, kResolveSTOP },
        { UCAL_WEEK_OF_YEAR, UCAL_DAY_OF_WEEK, kResolveSTOP },
        { UCAL_WEEK_OF_MONTH, UCAL_DAY_OF_WEEK, kResolveSTOP },
        { UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DAY_OF_WEEK, kResolveSTOP },
        { UCAL_WEEK_OF_YEAR, UCAL_DOW_LOCAL, kResolveSTOP },
        { UCAL_WEEK_OF_MONTH, UCAL_DOW_LOCAL, kResolveSTOP },
        { UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DOW_LOCAL, kResolveSTOP },
        { UCAL_DAY_OF_YEAR, kResolveSTOP },
        { kResolveRemap | UCAL_DAY_OF_MONTH, UCAL_YEAR, kResolveSTOP },  // if YEAR is set over YEAR_WOY use DAY_OF_MONTH
        { kResolveRemap | UCAL_WEEK_OF_YEAR, UCAL_YEAR_WOY, kResolveSTOP },  // if YEAR_WOY is set,  calc based on WEEK_OF_YEAR
        { kResolveSTOP }
    },
    {
        { UCAL_WEEK_OF_YEAR, kResolveSTOP },
        { UCAL_WEEK_OF_MONTH, kResolveSTOP },
        { UCAL_DAY_OF_WEEK_IN_MONTH, kResolveSTOP },
        { kResolveRemap | UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DAY_OF_WEEK, kResolveSTOP },
        { kResolveRemap | UCAL_DAY_OF_WEEK_IN_MONTH, UCAL_DOW_LOCAL, kResolveSTOP },
        { kResolveSTOP }
    },
    {{kResolveSTOP}}
};


const UFieldResolutionTable Calendar::kDOWPrecedence[] =
{
    {
        { UCAL_DAY_OF_WEEK,kResolveSTOP, kResolveSTOP },
        { UCAL_DOW_LOCAL,kResolveSTOP, kResolveSTOP },
        {kResolveSTOP}
    },
    {{kResolveSTOP}}
};

// precedence for calculating a year
const UFieldResolutionTable Calendar::kYearPrecedence[] =
{
    {
        { UCAL_YEAR, kResolveSTOP },
        { UCAL_EXTENDED_YEAR, kResolveSTOP },
        { UCAL_YEAR_WOY, UCAL_WEEK_OF_YEAR, kResolveSTOP },  // YEAR_WOY is useless without WEEK_OF_YEAR
        { kResolveSTOP }
    },
    {{kResolveSTOP}}
};


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


void Calendar::computeTime(UErrorCode& status) {
    if (!isLenient()) {
        validateFields(status);
        if (U_FAILURE(status)) {
            return;
        }
    }

    // Compute the Julian day
    int32_t julianDay = computeJulianDay();

    double millis = Grego::julianDayToMillis(julianDay);

#if defined (U_DEBUG_CAL)
    //  int32_t julianInsanityCheck =  (int32_t)ClockMath::floorDivide(millis, kOneDay);
    //  julianInsanityCheck += kEpochStartAsJulianDay;
    //  if(1 || julianInsanityCheck != julianDay) {
    //    fprintf(stderr, "%s:%d- D'oh- computed jules %d, to mills (%s)%.lf, recomputed %d\n",
    //            __FILE__, __LINE__, julianDay, millis<0.0?"NEG":"", millis, julianInsanityCheck);
    //  }
#endif

    int32_t millisInDay;

    // We only use MILLISECONDS_IN_DAY if it has been set by the user.
    // This makes it possible for the caller to set the calendar to a
    // time and call clear(MONTH) to reset the MONTH to January.  This
    // is legacy behavior.  Without this, clear(MONTH) has no effect,
    // since the internally set JULIAN_DAY is used.
    if (fStamp[UCAL_MILLISECONDS_IN_DAY] >= ((int32_t)kMinimumUserStamp) &&
            newestStamp(UCAL_AM_PM, UCAL_MILLISECOND, kUnset) <= fStamp[UCAL_MILLISECONDS_IN_DAY]) {
        millisInDay = internalGet(UCAL_MILLISECONDS_IN_DAY);
    } else {
        millisInDay = computeMillisInDay();
    }

    UDate t = 0;
    if (fStamp[UCAL_ZONE_OFFSET] >= ((int32_t)kMinimumUserStamp) || fStamp[UCAL_DST_OFFSET] >= ((int32_t)kMinimumUserStamp)) {
        t = millis + millisInDay - (internalGet(UCAL_ZONE_OFFSET) + internalGet(UCAL_DST_OFFSET));
    } else {
        // Compute the time zone offset and DST offset.  There are two potential
        // ambiguities here.  We'll assume a 2:00 am (wall time) switchover time
        // for discussion purposes here.
        //
        // 1. The positive offset change such as transition into DST.
        //    Here, a designated time of 2:00 am - 2:59 am does not actually exist.
        //    For this case, skippedWallTime option specifies the behavior.
        //    For example, 2:30 am is interpreted as;
        //      - WALLTIME_LAST(default): 3:30 am (DST) (interpreting 2:30 am as 31 minutes after 1:59 am (STD))
        //      - WALLTIME_FIRST: 1:30 am (STD) (interpreting 2:30 am as 30 minutes before 3:00 am (DST))
        //      - WALLTIME_NEXT_VALID: 3:00 am (DST) (next valid time after 2:30 am on a wall clock)
        // 2. The negative offset change such as transition out of DST.
        //    Here, a designated time of 1:00 am - 1:59 am can be in standard or DST.  Both are valid
        //    representations (the rep jumps from 1:59:59 DST to 1:00:00 Std).
        //    For this case, repeatedWallTime option specifies the behavior.
        //    For example, 1:30 am is interpreted as;
        //      - WALLTIME_LAST(default): 1:30 am (STD) - latter occurrence
        //      - WALLTIME_FIRST: 1:30 am (DST) - former occurrence
        //
        // In addition to above, when calendar is strict (not default), wall time falls into
        // the skipped time range will be processed as an error case.
        //
        // These special cases are mostly handled in #computeZoneOffset(long), except WALLTIME_NEXT_VALID
        // at positive offset change. The protected method computeZoneOffset(long) is exposed to Calendar
        // subclass implementations and marked as @stable. Strictly speaking, WALLTIME_NEXT_VALID
        // should be also handled in the same place, but we cannot change the code flow without deprecating
        // the protected method.
        //
        // We use the TimeZone object, unless the user has explicitly set the ZONE_OFFSET
        // or DST_OFFSET fields; then we use those fields.

        if (!isLenient() || fSkippedWallTime == UCAL_WALLTIME_NEXT_VALID) {
            // When strict, invalidate a wall time falls into a skipped wall time range.
            // When lenient and skipped wall time option is WALLTIME_NEXT_VALID,
            // the result time will be adjusted to the next valid time (on wall clock).
            int32_t zoneOffset = computeZoneOffset(millis, millisInDay, status);
            UDate tmpTime = millis + millisInDay - zoneOffset;

            int32_t raw, dst;
            fZone->getOffset(tmpTime, FALSE, raw, dst, status);

            if (U_SUCCESS(status)) {
                // zoneOffset != (raw + dst) only when the given wall time fall into
                // a skipped wall time range caused by positive zone offset transition.
                if (zoneOffset != (raw + dst)) {
                    if (!isLenient()) {
                        status = U_ILLEGAL_ARGUMENT_ERROR;
                    } else {
                        U_ASSERT(fSkippedWallTime == UCAL_WALLTIME_NEXT_VALID);
                        // Adjust time to the next valid wall clock time.
                        // At this point, tmpTime is on or after the zone offset transition causing
                        // the skipped time range.
                        UDate immediatePrevTransition;
                        UBool hasTransition = getImmediatePreviousZoneTransition(tmpTime, &immediatePrevTransition, status);
                        if (U_SUCCESS(status) && hasTransition) {
                            t = immediatePrevTransition;
                        }
                    }
                } else {
                    t = tmpTime;
                }
            }
        } else {
            t = millis + millisInDay - computeZoneOffset(millis, millisInDay, status);
        }
    }
    if (U_SUCCESS(status)) {
        internalSetTime(t);
    }
}

/**
 * Find the previous zone transtion near the given time.
 */
UBool Calendar::getImmediatePreviousZoneTransition(UDate base, UDate *transitionTime, UErrorCode& status) const {
    BasicTimeZone *btz = getBasicTimeZone();
    if (btz) {
        TimeZoneTransition trans;
        UBool hasTransition = btz->getPreviousTransition(base, TRUE, trans);
        if (hasTransition) {
            *transitionTime = trans.getTime();
            return TRUE;
        } else {
            // Could not find any transitions.
            // Note: This should never happen.
            status = U_INTERNAL_PROGRAM_ERROR;
        }
    } else {
        // If not BasicTimeZone, return unsupported error for now.
        // TODO: We may support non-BasicTimeZone in future.
        status = U_UNSUPPORTED_ERROR;
    }
    return FALSE;
}

/**
* 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.
* @stable ICU 2.0
*/
int32_t Calendar::computeMillisInDay() {
  // Do the time portion of the conversion.

    int32_t millisInDay = 0;

    // Find the best set of fields specifying the time of day.  There
    // are only two possibilities here; the HOUR_OF_DAY or the
    // AM_PM and the HOUR.
    int32_t hourOfDayStamp = fStamp[UCAL_HOUR_OF_DAY];
    int32_t hourStamp = (fStamp[UCAL_HOUR] > fStamp[UCAL_AM_PM])?fStamp[UCAL_HOUR]:fStamp[UCAL_AM_PM];
    int32_t bestStamp = (hourStamp > hourOfDayStamp) ? hourStamp : hourOfDayStamp;

    // Hours
    if (bestStamp != kUnset) {
        if (bestStamp == hourOfDayStamp) {
            // Don't normalize here; let overflow bump into the next period.
            // This is consistent with how we handle other fields.
            millisInDay += internalGet(UCAL_HOUR_OF_DAY);
        } else {
            // Don't normalize here; let overflow bump into the next period.
            // This is consistent with how we handle other fields.
            millisInDay += internalGet(UCAL_HOUR);
            millisInDay += 12 * internalGet(UCAL_AM_PM); // Default works for unset AM_PM
        }
    }

    // We use the fact that unset == 0; we start with millisInDay
    // == HOUR_OF_DAY.
    millisInDay *= 60;
    millisInDay += internalGet(UCAL_MINUTE); // now have minutes
    millisInDay *= 60;
    millisInDay += internalGet(UCAL_SECOND); // now have seconds
    millisInDay *= 1000;
    millisInDay += internalGet(UCAL_MILLISECOND); // now have millis

    return millisInDay;
}

/**
* 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.
* @stable ICU 2.0
*/
int32_t Calendar::computeZoneOffset(double millis, int32_t millisInDay, UErrorCode &ec) {
    int32_t rawOffset, dstOffset;
    UDate wall = millis + millisInDay;
    BasicTimeZone* btz = getBasicTimeZone();
    if (btz) {
        int duplicatedTimeOpt = (fRepeatedWallTime == UCAL_WALLTIME_FIRST) ? BasicTimeZone::kFormer : BasicTimeZone::kLatter;
        int nonExistingTimeOpt = (fSkippedWallTime == UCAL_WALLTIME_FIRST) ? BasicTimeZone::kLatter : BasicTimeZone::kFormer;
        btz->getOffsetFromLocal(wall, nonExistingTimeOpt, duplicatedTimeOpt, rawOffset, dstOffset, ec);
    } else {
        const TimeZone& tz = getTimeZone();
        // By default, TimeZone::getOffset behaves UCAL_WALLTIME_LAST for both.
        tz.getOffset(wall, TRUE, rawOffset, dstOffset, ec);

        UBool sawRecentNegativeShift = FALSE;
        if (fRepeatedWallTime == UCAL_WALLTIME_FIRST) {
            // Check if the given wall time falls into repeated time range
            UDate tgmt = wall - (rawOffset + dstOffset);

            // Any negative zone transition within last 6 hours?
            // Note: The maximum historic negative zone transition is -3 hours in the tz database.
            // 6 hour window would be sufficient for this purpose.
            int32_t tmpRaw, tmpDst;
            tz.getOffset(tgmt - 6*60*60*1000, FALSE, tmpRaw, tmpDst, ec);
            int32_t offsetDelta = (rawOffset + dstOffset) - (tmpRaw + tmpDst);

            U_ASSERT(offsetDelta < -6*60*60*1000);
            if (offsetDelta < 0) {
                sawRecentNegativeShift = TRUE;
                // Negative shift within last 6 hours. When UCAL_WALLTIME_FIRST is used and the given wall time falls
                // into the repeated time range, use offsets before the transition.
                // Note: If it does not fall into the repeated time range, offsets remain unchanged below.
                tz.getOffset(wall + offsetDelta, TRUE, rawOffset, dstOffset, ec);
            }
        }
        if (!sawRecentNegativeShift && fSkippedWallTime == UCAL_WALLTIME_FIRST) {
            // When skipped wall time option is WALLTIME_FIRST,
            // recalculate offsets from the resolved time (non-wall).
            // When the given wall time falls into skipped wall time,
            // the offsets will be based on the zone offsets AFTER
            // the transition (which means, earliest possibe interpretation).
            UDate tgmt = wall - (rawOffset + dstOffset);
            tz.getOffset(tgmt, FALSE, rawOffset, dstOffset, ec);
        }
    }
    return rawOffset + dstOffset;
}

int32_t Calendar::computeJulianDay()
{
    // We want to see if any of the date fields is newer than the
    // JULIAN_DAY.  If not, then we use JULIAN_DAY.  If so, then we do
    // the normal resolution.  We only use JULIAN_DAY if it has been
    // set by the user.  This makes it possible for the caller to set
    // the calendar to a time and call clear(MONTH) to reset the MONTH
    // to January.  This is legacy behavior.  Without this,
    // clear(MONTH) has no effect, since the internally set JULIAN_DAY
    // is used.
    if (fStamp[UCAL_JULIAN_DAY] >= (int32_t)kMinimumUserStamp) {
        int32_t bestStamp = newestStamp(UCAL_ERA, UCAL_DAY_OF_WEEK_IN_MONTH, kUnset);
        bestStamp = newestStamp(UCAL_YEAR_WOY, UCAL_EXTENDED_YEAR, bestStamp);
        if (bestStamp <= fStamp[UCAL_JULIAN_DAY]) {
            return internalGet(UCAL_JULIAN_DAY);
        }
    }

    UCalendarDateFields bestField = resolveFields(getFieldResolutionTable());
    if (bestField == UCAL_FIELD_COUNT) {
        bestField = UCAL_DAY_OF_MONTH;
    }

    return handleComputeJulianDay(bestField);
}

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

int32_t Calendar::handleComputeJulianDay(UCalendarDateFields bestField)  {
    UBool useMonth = (bestField == UCAL_DAY_OF_MONTH ||
        bestField == UCAL_WEEK_OF_MONTH ||
        bestField == UCAL_DAY_OF_WEEK_IN_MONTH);
    int32_t year;

    if (bestField == UCAL_WEEK_OF_YEAR) {
        year = internalGet(UCAL_YEAR_WOY, handleGetExtendedYear());
        internalSet(UCAL_EXTENDED_YEAR, year);
    } else {
        year = handleGetExtendedYear();
        internalSet(UCAL_EXTENDED_YEAR, year);
    }

#if defined (U_DEBUG_CAL)
    fprintf(stderr, "%s:%d: bestField= %s - y=%d\n", __FILE__, __LINE__, fldName(bestField), year);
#endif

    // Get the Julian day of the day BEFORE the start of this year.
    // If useMonth is true, get the day before the start of the month.

    // give calendar subclass a chance to have a default 'first' month
    int32_t month;

    if(isSet(UCAL_MONTH)) {
        month = internalGet(UCAL_MONTH);
    } else {
        month = getDefaultMonthInYear(year);
    }

    int32_t julianDay = handleComputeMonthStart(year, useMonth ? month : 0, useMonth);

    if (bestField == UCAL_DAY_OF_MONTH) {

        // give calendar subclass a chance to have a default 'first' dom
        int32_t dayOfMonth;
        if(isSet(UCAL_DAY_OF_MONTH)) {
            dayOfMonth = internalGet(UCAL_DAY_OF_MONTH,1);
        } else {
            dayOfMonth = getDefaultDayInMonth(year, month);
        }
        return julianDay + dayOfMonth;
    }

    if (bestField == UCAL_DAY_OF_YEAR) {
        return julianDay + internalGet(UCAL_DAY_OF_YEAR);
    }

    int32_t firstDayOfWeek = getFirstDayOfWeek(); // Localized fdw

    // At this point julianDay is the 0-based day BEFORE the first day of
    // January 1, year 1 of the given calendar.  If julianDay == 0, it
    // specifies (Jan. 1, 1) - 1, in whatever calendar we are using (Julian
    // or Gregorian). (or it is before the month we are in, if useMonth is True)

    // At this point we need to process the WEEK_OF_MONTH or
    // WEEK_OF_YEAR, which are similar, or the DAY_OF_WEEK_IN_MONTH.
    // First, perform initial shared computations.  These locate the
    // first week of the period.

    // Get the 0-based localized DOW of day one of the month or year.
    // Valid range 0..6.
    int32_t first = julianDayToDayOfWeek(julianDay + 1) - firstDayOfWeek;
    if (first < 0) {
        first += 7;
    }

    int32_t dowLocal = getLocalDOW();

    // Find the first target DOW (dowLocal) in the month or year.
    // Actually, it may be just before the first of the month or year.
    // It will be an integer from -5..7.
    int32_t date = 1 - first + dowLocal;

    if (bestField == UCAL_DAY_OF_WEEK_IN_MONTH) {
        // Adjust the target DOW to be in the month or year.
        if (date < 1) {
            date += 7;
        }

        // The only trickiness occurs if the day-of-week-in-month is
        // negative.
        int32_t dim = internalGet(UCAL_DAY_OF_WEEK_IN_MONTH, 1);
        if (dim >= 0) {
            date += 7*(dim - 1);

        } else {
            // Move date to the last of this day-of-week in this month,
            // then back up as needed.  If dim==-1, we don't back up at
            // all.  If dim==-2, we back up once, etc.  Don't back up
            // past the first of the given day-of-week in this month.
            // Note that we handle -2, -3, etc. correctly, even though
            // values < -1 are technically disallowed.
            int32_t m = internalGet(UCAL_MONTH, UCAL_JANUARY);
            int32_t monthLength = handleGetMonthLength(year, m);
            date += ((monthLength - date) / 7 + dim + 1) * 7;
        }
    } else {
#if defined (U_DEBUG_CAL)
        fprintf(stderr, "%s:%d - bf= %s\n", __FILE__, __LINE__, fldName(bestField));
#endif

        if(bestField == UCAL_WEEK_OF_YEAR) {  // ------------------------------------- WOY -------------
            if(!isSet(UCAL_YEAR_WOY) ||  // YWOY not set at all or
                ( (resolveFields(kYearPrecedence) != UCAL_YEAR_WOY) // YWOY doesn't have precedence
                && (fStamp[UCAL_YEAR_WOY]!=kInternallySet) ) ) // (excluding where all fields are internally set - then YWOY is used)
            {
                // need to be sure to stay in 'real' year.
                int32_t woy = internalGet(bestField);

                int32_t nextJulianDay = handleComputeMonthStart(year+1, 0, FALSE); // jd of day before jan 1
                int32_t nextFirst = julianDayToDayOfWeek(nextJulianDay + 1) - firstDayOfWeek;

                if (nextFirst < 0) { // 0..6 ldow of Jan 1
                    nextFirst += 7;
                }

                if(woy==1) {  // FIRST WEEK ---------------------------------
#if defined (U_DEBUG_CAL)
                    fprintf(stderr, "%s:%d - woy=%d, yp=%d, nj(%d)=%d, nf=%d", __FILE__, __LINE__,
                        internalGet(bestField), resolveFields(kYearPrecedence), year+1,
                        nextJulianDay, nextFirst);

                    fprintf(stderr, " next: %d DFW,  min=%d   \n", (7-nextFirst), getMinimalDaysInFirstWeek() );
#endif

                    // nextFirst is now the localized DOW of Jan 1  of y-woy+1
                    if((nextFirst > 0) &&   // Jan 1 starts on FDOW
                        (7-nextFirst) >= getMinimalDaysInFirstWeek()) // or enough days in the week
                    {
                        // Jan 1 of (yearWoy+1) is in yearWoy+1 - recalculate JD to next year
#if defined (U_DEBUG_CAL)
                        fprintf(stderr, "%s:%d - was going to move JD from %d to %d [d%d]\n", __FILE__, __LINE__,
                            julianDay, nextJulianDay, (nextJulianDay-julianDay));
#endif
                        julianDay = nextJulianDay;

                        // recalculate 'first' [0-based local dow of jan 1]
                        first = julianDayToDayOfWeek(julianDay + 1) - firstDayOfWeek;
                        if (first < 0) {
                            first += 7;
                        }
                        // recalculate date.
                        date = 1 - first + dowLocal;
                    }
                } else if(woy>=getLeastMaximum(bestField)) {
                    // could be in the last week- find out if this JD would overstep
                    int32_t testDate = date;
                    if ((7 - first) < getMinimalDaysInFirstWeek()) {
                        testDate += 7;
                    }

                    // Now adjust for the week number.
                    testDate += 7 * (woy - 1);

#if defined (U_DEBUG_CAL)
                    fprintf(stderr, "%s:%d - y=%d, y-1=%d doy%d, njd%d (C.F. %d)\n",
                        __FILE__, __LINE__, year, year-1, testDate, julianDay+testDate, nextJulianDay);
#endif
                    if(julianDay+testDate > nextJulianDay) { // is it past Dec 31?  (nextJulianDay is day BEFORE year+1's  Jan 1)
                        // Fire up the calculating engines.. retry YWOY = (year-1)
                        julianDay = handleComputeMonthStart(year-1, 0, FALSE); // jd before Jan 1 of previous year
                        first = julianDayToDayOfWeek(julianDay + 1) - firstDayOfWeek; // 0 based local dow   of first week

                        if(first < 0) { // 0..6
                            first += 7;
                        }
                        date = 1 - first + dowLocal;

#if defined (U_DEBUG_CAL)
                        fprintf(stderr, "%s:%d - date now %d, jd%d, ywoy%d\n",
                            __FILE__, __LINE__, date, julianDay, year-1);
#endif


                    } /* correction needed */
                } /* leastmaximum */
            } /* resolvefields(year) != year_woy */
        } /* bestfield != week_of_year */

        // assert(bestField == WEEK_OF_MONTH || bestField == WEEK_OF_YEAR)
        // Adjust for minimal days in first week
        if ((7 - first) < getMinimalDaysInFirstWeek()) {
            date += 7;
        }

        // Now adjust for the week number.
        date += 7 * (internalGet(bestField) - 1);
    }

    return julianDay + date;
}

int32_t
Calendar::getDefaultMonthInYear(int32_t /*eyear*/)
{
    return 0;
}

int32_t
Calendar::getDefaultDayInMonth(int32_t /*eyear*/, int32_t /*month*/)
{
    return 1;
}


int32_t Calendar::getLocalDOW()
{
  // Get zero-based localized DOW, valid range 0..6.  This is the DOW
    // we are looking for.
    int32_t dowLocal = 0;
    switch (resolveFields(kDOWPrecedence)) {
    case UCAL_DAY_OF_WEEK:
        dowLocal = internalGet(UCAL_DAY_OF_WEEK) - fFirstDayOfWeek;
        break;
    case UCAL_DOW_LOCAL:
        dowLocal = internalGet(UCAL_DOW_LOCAL) - 1;
        break;
    default:
        break;
    }
    dowLocal = dowLocal % 7;
    if (dowLocal < 0) {
        dowLocal += 7;
    }
    return dowLocal;
}

int32_t Calendar::handleGetExtendedYearFromWeekFields(int32_t yearWoy, int32_t woy)
{
    // We have UCAL_YEAR_WOY and UCAL_WEEK_OF_YEAR - from those, determine
    // what year we fall in, so that other code can set it properly.
    // (code borrowed from computeWeekFields and handleComputeJulianDay)
    //return yearWoy;

    // First, we need a reliable DOW.
    UCalendarDateFields bestField = resolveFields(kDatePrecedence); // !! Note: if subclasses have a different table, they should override handleGetExtendedYearFromWeekFields

    // Now, a local DOW
    int32_t dowLocal = getLocalDOW(); // 0..6
    int32_t firstDayOfWeek = getFirstDayOfWeek(); // Localized fdw
    int32_t jan1Start = handleComputeMonthStart(yearWoy, 0, FALSE);
    int32_t nextJan1Start = handleComputeMonthStart(yearWoy+1, 0, FALSE); // next year's Jan1 start

    // At this point julianDay is the 0-based day BEFORE the first day of
    // January 1, year 1 of the given calendar.  If julianDay == 0, it
    // specifies (Jan. 1, 1) - 1, in whatever calendar we are using (Julian
    // or Gregorian). (or it is before the month we are in, if useMonth is True)

    // At this point we need to process the WEEK_OF_MONTH or
    // WEEK_OF_YEAR, which are similar, or the DAY_OF_WEEK_IN_MONTH.
    // First, perform initial shared computations.  These locate the
    // first week of the period.