295 lines
9.9 KiB
C++
295 lines
9.9 KiB
C++
/*
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*****************************************************************************
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* Copyright (C) 2007-2008, International Business Machines Corporation
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* and others. All Rights Reserved.
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*****************************************************************************
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*
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* File CHNSECAL.H
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*
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* Modification History:
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*
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* Date Name Description
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* 9/18/2007 ajmacher ported from java ChineseCalendar
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*****************************************************************************
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*/
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#ifndef CHNSECAL_H
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#define CHNSECAL_H
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_FORMATTING
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#include "unicode/calendar.h"
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U_NAMESPACE_BEGIN
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/**
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* <code>ChineseCalendar</code> is a concrete subclass of {@link Calendar}
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* that implements a traditional Chinese calendar. The traditional Chinese
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* calendar is a lunisolar calendar: Each month starts on a new moon, and
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* the months are numbered according to solar events, specifically, to
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* guarantee that month 11 always contains the winter solstice. In order
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* to accomplish this, leap months are inserted in certain years. Leap
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* months are numbered the same as the month they follow. The decision of
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* which month is a leap month depends on the relative movements of the sun
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* and moon.
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*
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* <p>This class defines one addition field beyond those defined by
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* <code>Calendar</code>: The <code>IS_LEAP_MONTH</code> field takes the
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* value of 0 for normal months, or 1 for leap months.
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*
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* <p>All astronomical computations are performed with respect to a time
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* zone of GMT+8:00 and a longitude of 120 degrees east. Although some
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* calendars implement a historically more accurate convention of using
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* Beijing's local longitude (116 degrees 25 minutes east) and time zone
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* (GMT+7:45:40) for dates before 1929, we do not implement this here.
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*
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* <p>Years are counted in two different ways in the Chinese calendar. The
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* first method is by sequential numbering from the 61st year of the reign
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* of Huang Di, 2637 BCE, which is designated year 1 on the Chinese
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* calendar. The second method uses 60-year cycles from the same starting
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* point, which is designated year 1 of cycle 1. In this class, the
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* <code>EXTENDED_YEAR</code> field contains the sequential year count.
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* The <code>ERA</code> field contains the cycle number, and the
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* <code>YEAR</code> field contains the year of the cycle, a value between
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* 1 and 60.
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*
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* <p>There is some variation in what is considered the starting point of
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* the calendar, with some sources starting in the first year of the reign
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* of Huang Di, rather than the 61st. This gives continuous year numbers
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* 60 years greater and cycle numbers one greater than what this class
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* implements.
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*
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* <p>Because <code>ChineseCalendar</code> defines an additional field and
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* redefines the way the <code>ERA</code> field is used, it requires a new
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* format class, <code>ChineseDateFormat</code>. As always, use the
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* methods <code>DateFormat.getXxxInstance(Calendar cal,...)</code> to
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* obtain a formatter for this calendar.
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*
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* <p>References:<ul>
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*
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* <li>Dershowitz and Reingold, <i>Calendrical Calculations</i>,
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* Cambridge University Press, 1997</li>
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*
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* <li>Helmer Aslaksen's
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* <a href="http://www.math.nus.edu.sg/aslaksen/calendar/chinese.shtml">
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* Chinese Calendar page</a></li>
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*
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* <li>The <a href="http://www.tondering.dk/claus/calendar.html">
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* Calendar FAQ</a></li>
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*
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* </ul>
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*
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* <p>
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* This class should not be subclassed.</p>
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* <p>
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* ChineseCalendar usually should be instantiated using
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* {@link com.ibm.icu.util.Calendar#getInstance(ULocale)} passing in a <code>ULocale</code>
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* with the tag <code>"@calendar=chinese"</code>.</p>
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*
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* @see com.ibm.icu.text.ChineseDateFormat
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* @see com.ibm.icu.util.Calendar
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* @author Alan Liu
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* @stable ICU 2.8
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*/
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class ChineseCalendar : public Calendar {
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public:
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//-------------------------------------------------------------------------
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// Constructors...
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//-------------------------------------------------------------------------
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/**
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* Constructs an ChineseCalendar based on the current time in the default time zone
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* with the given locale.
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*
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* @param aLocale The given locale.
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* @param success Indicates the status of ChineseCalendar object construction.
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* Returns U_ZERO_ERROR if constructed successfully.
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* @internal
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*/
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ChineseCalendar(const Locale& aLocale, UErrorCode &success);
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/**
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* Copy Constructor
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* @internal
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*/
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ChineseCalendar(const ChineseCalendar& other);
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/**
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* Destructor.
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* @internal
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*/
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virtual ~ChineseCalendar();
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// clone
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virtual Calendar* clone() const;
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private:
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//-------------------------------------------------------------------------
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// Internal data....
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//-------------------------------------------------------------------------
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UBool isLeapYear;
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//----------------------------------------------------------------------
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// Calendar framework
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//----------------------------------------------------------------------
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protected:
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virtual int32_t handleGetLimit(UCalendarDateFields field, ELimitType limitType) const;
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virtual int32_t handleGetMonthLength(int32_t extendedYear, int32_t month) const;
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virtual int32_t handleComputeMonthStart(int32_t eyear, int32_t month, UBool useMonth) const;
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virtual int32_t handleGetExtendedYear();
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virtual void handleComputeFields(int32_t julianDay, UErrorCode &status);
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virtual const UFieldResolutionTable* getFieldResolutionTable() const;
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public:
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virtual void add(UCalendarDateFields field, int32_t amount, UErrorCode &status);
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virtual void add(EDateFields field, int32_t amount, UErrorCode &status);
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virtual void roll(UCalendarDateFields field, int32_t amount, UErrorCode &status);
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virtual void roll(EDateFields field, int32_t amount, UErrorCode &status);
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//----------------------------------------------------------------------
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// Internal methods & astronomical calculations
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//----------------------------------------------------------------------
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private:
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static const UFieldResolutionTable CHINESE_DATE_PRECEDENCE[];
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static double daysToMillis(double days);
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static double millisToDays(double millis);
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virtual int32_t winterSolstice(int32_t gyear) const;
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virtual int32_t newMoonNear(double days, UBool after) const;
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virtual int32_t synodicMonthsBetween(int32_t day1, int32_t day2) const;
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virtual int32_t majorSolarTerm(int32_t days) const;
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virtual UBool hasNoMajorSolarTerm(int32_t newMoon) const;
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virtual UBool isLeapMonthBetween(int32_t newMoon1, int32_t newMoon2) const;
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virtual void computeChineseFields(int32_t days, int32_t gyear,
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int32_t gmonth, UBool setAllFields);
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virtual int32_t newYear(int32_t gyear) const;
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virtual void offsetMonth(int32_t newMoon, int32_t dom, int32_t delta);
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// UObject stuff
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public:
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/**
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* @return The class ID for this object. All objects of a given class have the
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* same class ID. Objects of other classes have different class IDs.
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* @internal
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*/
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virtual UClassID getDynamicClassID(void) const;
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/**
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* Return the class ID for this class. This is useful only for comparing to a return
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* value from getDynamicClassID(). For example:
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*
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* Base* polymorphic_pointer = createPolymorphicObject();
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* if (polymorphic_pointer->getDynamicClassID() ==
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* Derived::getStaticClassID()) ...
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*
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* @return The class ID for all objects of this class.
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* @internal
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*/
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U_I18N_API static UClassID U_EXPORT2 getStaticClassID(void);
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/**
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* return the calendar type, "chinese".
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*
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* @return calendar type
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* @internal
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*/
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virtual const char * getType() const;
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protected:
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/**
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* (Overrides Calendar) Return true if the current date for this Calendar is in
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* Daylight Savings Time. Recognizes DST_OFFSET, if it is set.
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*
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* @param status Fill-in parameter which receives the status of this operation.
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* @return True if the current date for this Calendar is in Daylight Savings Time,
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* false, otherwise.
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* @internal
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*/
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virtual UBool inDaylightTime(UErrorCode& status) const;
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/**
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* Returns TRUE because the Islamic Calendar does have a default century
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* @internal
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*/
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virtual UBool haveDefaultCentury() const;
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/**
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* Returns the date of the start of the default century
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* @return start of century - in milliseconds since epoch, 1970
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* @internal
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*/
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virtual UDate defaultCenturyStart() const;
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/**
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* Returns the year in which the default century begins
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* @internal
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*/
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virtual int32_t defaultCenturyStartYear() const;
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private: // default century stuff.
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/**
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* The system maintains a static default century start date. This is initialized
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* the first time it is used. Before then, it is set to SYSTEM_DEFAULT_CENTURY to
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* indicate an uninitialized state. Once the system default century date and year
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* are set, they do not change.
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*/
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static UDate fgSystemDefaultCenturyStart;
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/**
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* See documentation for systemDefaultCenturyStart.
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*/
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static int32_t fgSystemDefaultCenturyStartYear;
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/**
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* Default value that indicates the defaultCenturyStartYear is unitialized
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*/
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static const int32_t fgSystemDefaultCenturyYear;
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/**
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* start of default century, as a date
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*/
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static const UDate fgSystemDefaultCentury;
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/**
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* Returns the beginning date of the 100-year window that dates
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* with 2-digit years are considered to fall within.
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*/
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UDate internalGetDefaultCenturyStart(void) const;
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/**
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* Returns the first year of the 100-year window that dates with
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* 2-digit years are considered to fall within.
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*/
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int32_t internalGetDefaultCenturyStartYear(void) const;
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/**
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* Initializes the 100-year window that dates with 2-digit years
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* are considered to fall within so that its start date is 80 years
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* before the current time.
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*/
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static void initializeSystemDefaultCentury(void);
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ChineseCalendar(); // default constructor not implemented
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};
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U_NAMESPACE_END
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#endif
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#endif
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