Check in the pristine copy of ICU 4.6...

icu46/source/i18n/chnsecal.h

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