icuSources/i18n/unicode/timezone.h

   1 /*************************************************************************
   2 * Copyright (c) 1997-2010, International Business Machines Corporation
   3 * and others. All Rights Reserved.
   4 **************************************************************************
   5 *
   6 * File TIMEZONE.H
   7 *
   8 * Modification History:
   9 *
  10 *   Date        Name        Description
  11 *   04/21/97    aliu        Overhauled header.
  12 *   07/09/97    helena      Changed createInstance to createDefault.
  13 *   08/06/97    aliu        Removed dependency on internal header for Hashtable.
  14 *   08/10/98    stephen        Changed getDisplayName() API conventions to match
  15 *   08/19/98    stephen        Changed createTimeZone() to never return 0
  16 *   09/02/98    stephen        Sync to JDK 1.2 8/31
  17 *                            - Added getOffset(... monthlen ...)
  18 *                            - Added hasSameRules()
  19 *   09/15/98    stephen        Added getStaticClassID
  20 *   12/03/99    aliu        Moved data out of static table into icudata.dll.
  21 *                           Hashtable replaced by new static data structures.
  22 *   12/14/99    aliu        Made GMT public.
  23 *   08/15/01    grhoten     Made GMT private and added the getGMT() function
  24 **************************************************************************
  25 */
  26
  27 #ifndef TIMEZONE_H
  28 #define TIMEZONE_H
  29
  30 #include "unicode/utypes.h"
  31
  32 /**
  33  * \file
  34  * \brief C++ API: TimeZone object
  35  */
  36
  37 #if !UCONFIG_NO_FORMATTING
  38
  39 #include "unicode/uobject.h"
  40 #include "unicode/unistr.h"
  41 #include "unicode/ures.h"
  42
  43 U_NAMESPACE_BEGIN
  44
  45 class StringEnumeration;
  46
  47 /**
  48  *
  49  * <code>TimeZone</code> represents a time zone offset, and also figures out daylight
  50  * savings.
  51  *
  52  * <p>
  53  * Typically, you get a <code>TimeZone</code> using <code>createDefault</code>
  54  * which creates a <code>TimeZone</code> based on the time zone where the program
  55  * is running. For example, for a program running in Japan, <code>createDefault</code>
  56  * creates a <code>TimeZone</code> object based on Japanese Standard Time.
  57  *
  58  * <p>
  59  * You can also get a <code>TimeZone</code> using <code>createTimeZone</code> along
  60  * with a time zone ID. For instance, the time zone ID for the US Pacific
  61  * Time zone is "America/Los_Angeles". So, you can get a Pacific Time <code>TimeZone</code> object
  62  * with:
  63  * \htmlonly<blockquote>\endhtmlonly
  64  * <pre>
  65  * TimeZone *tz = TimeZone::createTimeZone("America/Los_Angeles");
  66  * </pre>
  67  * \htmlonly</blockquote>\endhtmlonly
  68  * You can use <code>getAvailableIDs</code> method to iterate through
  69  * all the supported time zone IDs. You can then choose a
  70  * supported ID to get a <code>TimeZone</code>.
  71  * If the time zone you want is not represented by one of the
  72  * supported IDs, then you can create a custom time zone ID with
  73  * the following syntax:
  74  *
  75  * \htmlonly<blockquote>\endhtmlonly
  76  * <pre>
  77  * GMT[+|-]hh[[:]mm]
  78  * </pre>
  79  * \htmlonly</blockquote>\endhtmlonly
  80  *
  81  * For example, you might specify GMT+14:00 as a custom
  82  * time zone ID.  The <code>TimeZone</code> that is returned
  83  * when you specify a custom time zone ID does not include
  84  * daylight savings time.
  85  *
  86  * TimeZone is an abstract class representing a time zone.  A TimeZone is needed for
  87  * Calendar to produce local time for a particular time zone.  A TimeZone comprises
  88  * three basic pieces of information:
  89  * <ul>
  90  *    <li>A time zone offset; that, is the number of milliseconds to add or subtract
  91  *      from a time expressed in terms of GMT to convert it to the same time in that
  92  *      time zone (without taking daylight savings time into account).</li>
  93  *    <li>Logic necessary to take daylight savings time into account if daylight savings
  94  *      time is observed in that time zone (e.g., the days and hours on which daylight
  95  *      savings time begins and ends).</li>
  96  *    <li>An ID.  This is a text string that uniquely identifies the time zone.</li>
  97  * </ul>
  98  *
  99  * (Only the ID is actually implemented in TimeZone; subclasses of TimeZone may handle
 100  * daylight savings time and GMT offset in different ways.  Currently we only have one
 101  * TimeZone subclass: SimpleTimeZone.)
 102  * <P>
 103  * The TimeZone class contains a static list containing a TimeZone object for every
 104  * combination of GMT offset and daylight-savings time rules currently in use in the
 105  * world, each with a unique ID.  Each ID consists of a region (usually a continent or
 106  * ocean) and a city in that region, separated by a slash, (for example, US Pacific
 107  * Time is "America/Los_Angeles.")  Because older versions of this class used
 108  * three- or four-letter abbreviations instead, there is also a table that maps the older
 109  * abbreviations to the newer ones (for example, "PST" maps to "America/Los_Angeles").
 110  * Anywhere the API requires an ID, you can use either form.
 111  * <P>
 112  * To create a new TimeZone, you call the factory function TimeZone::createTimeZone()
 113  * and pass it a time zone ID.  You can use the createEnumeration() function to
 114  * obtain a list of all the time zone IDs recognized by createTimeZone().
 115  * <P>
 116  * You can also use TimeZone::createDefault() to create a TimeZone.  This function uses
 117  * platform-specific APIs to produce a TimeZone for the time zone corresponding to
 118  * the client's computer's physical location.  For example, if you're in Japan (assuming
 119  * your machine is set up correctly), TimeZone::createDefault() will return a TimeZone
 120  * for Japanese Standard Time ("Asia/Tokyo").
 121  */
 122 class U_I18N_API TimeZone : public UObject {
 123 public:
 124     /**
 125      * @stable ICU 2.0
 126      */
 127     virtual ~TimeZone();
 128
 129     /**
 130      * The GMT time zone has a raw offset of zero and does not use daylight
 131      * savings time. This is a commonly used time zone.
 132      * @return the GMT time zone.
 133      * @stable ICU 2.0
 134      */
 135     static const TimeZone* U_EXPORT2 getGMT(void);
 136
 137     /**
 138      * Creates a <code>TimeZone</code> for the given ID.
 139      * @param ID the ID for a <code>TimeZone</code>, such as "America/Los_Angeles",
 140      * or a custom ID such as "GMT-8:00".
 141      * @return the specified <code>TimeZone</code>, or the GMT zone if the given ID
 142      * cannot be understood.  Return result guaranteed to be non-null.  If you
 143      * require that the specific zone asked for be returned, check the ID of the
 144      * return result.
 145      * @stable ICU 2.0
 146      */
 147     static TimeZone* U_EXPORT2 createTimeZone(const UnicodeString& ID);
 148
 149     /**
 150      * Returns an enumeration over all recognized time zone IDs. (i.e.,
 151      * all strings that createTimeZone() accepts)
 152      *
 153      * @return an enumeration object, owned by the caller.
 154      * @stable ICU 2.4
 155      */
 156     static StringEnumeration* U_EXPORT2 createEnumeration();
 157
 158     /**
 159      * Returns an enumeration over time zone IDs with a given raw
 160      * offset from GMT.  There may be several times zones with the
 161      * same GMT offset that differ in the way they handle daylight
 162      * savings time.  For example, the state of Arizona doesn't
 163      * observe daylight savings time.  If you ask for the time zone
 164      * IDs corresponding to GMT-7:00, you'll get back an enumeration
 165      * over two time zone IDs: "America/Denver," which corresponds to
 166      * Mountain Standard Time in the winter and Mountain Daylight Time
 167      * in the summer, and "America/Phoenix", which corresponds to
 168      * Mountain Standard Time year-round, even in the summer.
 169      *
 170      * @param rawOffset an offset from GMT in milliseconds, ignoring
 171      * the effect of daylight savings time, if any
 172      * @return an enumeration object, owned by the caller
 173      * @stable ICU 2.4
 174      */
 175     static StringEnumeration* U_EXPORT2 createEnumeration(int32_t rawOffset);
 176
 177     /**
 178      * Returns an enumeration over time zone IDs associated with the
 179      * given country.  Some zones are affiliated with no country
 180      * (e.g., "UTC"); these may also be retrieved, as a group.
 181      *
 182      * @param country The ISO 3166 two-letter country code, or NULL to
 183      * retrieve zones not affiliated with any country.
 184      * @return an enumeration object, owned by the caller
 185      * @stable ICU 2.4
 186      */
 187     static StringEnumeration* U_EXPORT2 createEnumeration(const char* country);
 188
 189     /**
 190      * Returns the number of IDs in the equivalency group that
 191      * includes the given ID.  An equivalency group contains zones
 192      * that have the same GMT offset and rules.
 193      *
 194      * <p>The returned count includes the given ID; it is always >= 1.
 195      * The given ID must be a system time zone.  If it is not, returns
 196      * zero.
 197      * @param id a system time zone ID
 198      * @return the number of zones in the equivalency group containing
 199      * 'id', or zero if 'id' is not a valid system ID
 200      * @see #getEquivalentID
 201      * @stable ICU 2.0
 202      */
 203     static int32_t U_EXPORT2 countEquivalentIDs(const UnicodeString& id);
 204
 205     /**
 206      * Returns an ID in the equivalency group that
 207      * includes the given ID.  An equivalency group contains zones
 208      * that have the same GMT offset and rules.
 209      *
 210      * <p>The given index must be in the range 0..n-1, where n is the
 211      * value returned by <code>countEquivalentIDs(id)</code>.  For
 212      * some value of 'index', the returned value will be equal to the
 213      * given id.  If the given id is not a valid system time zone, or
 214      * if 'index' is out of range, then returns an empty string.
 215      * @param id a system time zone ID
 216      * @param index a value from 0 to n-1, where n is the value
 217      * returned by <code>countEquivalentIDs(id)</code>
 218      * @return the ID of the index-th zone in the equivalency group
 219      * containing 'id', or an empty string if 'id' is not a valid
 220      * system ID or 'index' is out of range
 221      * @see #countEquivalentIDs
 222      * @stable ICU 2.0
 223      */
 224     static const UnicodeString U_EXPORT2 getEquivalentID(const UnicodeString& id,
 225                                                int32_t index);
 226
 227     /**
 228      * Creates a new copy of the default TimeZone for this host. Unless the default time
 229      * zone has already been set using adoptDefault() or setDefault(), the default is
 230      * determined by querying the system using methods in TPlatformUtilities. If the
 231      * system routines fail, or if they specify a TimeZone or TimeZone offset which is not
 232      * recognized, the TimeZone indicated by the ID kLastResortID is instantiated
 233      * and made the default.
 234      *
 235      * @return   A default TimeZone. Clients are responsible for deleting the time zone
 236      *           object returned.
 237      * @stable ICU 2.0
 238      */
 239     static TimeZone* U_EXPORT2 createDefault(void);
 240
 241     /**
 242      * Sets the default time zone (i.e., what's returned by createDefault()) to be the
 243      * specified time zone.  If NULL is specified for the time zone, the default time
 244      * zone is set to the default host time zone.  This call adopts the TimeZone object
 245      * passed in; the clent is no longer responsible for deleting it.
 246      *
 247      * @param zone  A pointer to the new TimeZone object to use as the default.
 248      * @stable ICU 2.0
 249      */
 250     static void U_EXPORT2 adoptDefault(TimeZone* zone);
 251
 252     /**
 253      * Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted;
 254      * the caller remains responsible for deleting it.
 255      *
 256      * @param zone  The given timezone.
 257      * @system
 258      */
 259     static void U_EXPORT2 setDefault(const TimeZone& zone);
 260
 261     /**
 262      * Returns the timezone data version currently used by ICU.
 263      * @param status Output param to filled in with a success or an error.
 264      * @return the version string, such as "2007f"
 265      * @stable ICU 3.8
 266      */
 267     static const char* U_EXPORT2 getTZDataVersion(UErrorCode& status);
 268
 269     /**
 270      * Returns the canonical system timezone ID or the normalized
 271      * custom time zone ID for the given time zone ID.
 272      * @param id            The input time zone ID to be canonicalized.
 273      * @param canonicalID   Receives the canonical system time zone ID
 274      *                      or the custom time zone ID in normalized format.
 275      * @param status        Recevies the status.  When the given time zone ID
 276      *                      is neither a known system time zone ID nor a
 277      *                      valid custom time zone ID, U_ILLEGAL_ARGUMENT_ERROR
 278      *                      is set.
 279      * @return A reference to the result.
 280      * @stable ICU 4.0
 281      */
 282     static UnicodeString& U_EXPORT2 getCanonicalID(const UnicodeString& id,
 283         UnicodeString& canonicalID, UErrorCode& status);
 284
 285     /**
 286      * Returns the canonical system time zone ID or the normalized
 287      * custom time zone ID for the given time zone ID.
 288      * @param id            The input time zone ID to be canonicalized.
 289      * @param canonicalID   Receives the canonical system time zone ID
 290      *                      or the custom time zone ID in normalized format.
 291      * @param isSystemID    Receives if the given ID is a known system
 292      *                      time zone ID.
 293      * @param status        Recevies the status.  When the given time zone ID
 294      *                      is neither a known system time zone ID nor a
 295      *                      valid custom time zone ID, U_ILLEGAL_ARGUMENT_ERROR
 296      *                      is set.
 297      * @return A reference to the result.
 298      * @stable ICU 4.0
 299      */
 300     static UnicodeString& U_EXPORT2 getCanonicalID(const UnicodeString& id,
 301         UnicodeString& canonicalID, UBool& isSystemID, UErrorCode& status);
 302
 303     /**
 304      * Returns true if the two TimeZones are equal.  (The TimeZone version only compares
 305      * IDs, but subclasses are expected to also compare the fields they add.)
 306      *
 307      * @param that  The TimeZone object to be compared with.
 308      * @return      True if the given TimeZone is equal to this TimeZone; false
 309      *              otherwise.
 310      * @stable ICU 2.0
 311      */
 312     virtual UBool operator==(const TimeZone& that) const;
 313
 314     /**
 315      * Returns true if the two TimeZones are NOT equal; that is, if operator==() returns
 316      * false.
 317      *
 318      * @param that  The TimeZone object to be compared with.
 319      * @return      True if the given TimeZone is not equal to this TimeZone; false
 320      *              otherwise.
 321      * @stable ICU 2.0
 322      */
 323     UBool operator!=(const TimeZone& that) const {return !operator==(that);}
 324
 325     /**
 326      * Returns the TimeZone's adjusted GMT offset (i.e., the number of milliseconds to add
 327      * to GMT to get local time in this time zone, taking daylight savings time into
 328      * account) as of a particular reference date.  The reference date is used to determine
 329      * whether daylight savings time is in effect and needs to be figured into the offset
 330      * that is returned (in other words, what is the adjusted GMT offset in this time zone
 331      * at this particular date and time?).  For the time zones produced by createTimeZone(),
 332      * the reference data is specified according to the Gregorian calendar, and the date
 333      * and time fields are local standard time.
 334      *
 335      * <p>Note: Don't call this method. Instead, call the getOffset(UDate...) overload,
 336      * which returns both the raw and the DST offset for a given time. This method
 337      * is retained only for backward compatibility.
 338      *
 339      * @param era        The reference date's era
 340      * @param year       The reference date's year
 341      * @param month      The reference date's month (0-based; 0 is January)
 342      * @param day        The reference date's day-in-month (1-based)
 343      * @param dayOfWeek  The reference date's day-of-week (1-based; 1 is Sunday)
 344      * @param millis     The reference date's milliseconds in day, local standard time
 345      * @param status     Output param to filled in with a success or an error.
 346      * @return           The offset in milliseconds to add to GMT to get local time.
 347      * @stable ICU 2.0
 348      */
 349     virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day,
 350                               uint8_t dayOfWeek, int32_t millis, UErrorCode& status) const = 0;
 351
 352     /**
 353      * Gets the time zone offset, for current date, modified in case of
 354      * daylight savings. This is the offset to add *to* UTC to get local time.
 355      *
 356      * <p>Note: Don't call this method. Instead, call the getOffset(UDate...) overload,
 357      * which returns both the raw and the DST offset for a given time. This method
 358      * is retained only for backward compatibility.
 359      *
 360      * @param era the era of the given date.
 361      * @param year the year in the given date.
 362      * @param month the month in the given date.
 363      * Month is 0-based. e.g., 0 for January.
 364      * @param day the day-in-month of the given date.
 365      * @param dayOfWeek the day-of-week of the given date.
 366      * @param milliseconds the millis in day in <em>standard</em> local time.
 367      * @param monthLength the length of the given month in days.
 368      * @param status     Output param to filled in with a success or an error.
 369      * @return the offset to add *to* GMT to get local time.
 370      * @stable ICU 2.0
 371      */
 372     virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day,
 373                            uint8_t dayOfWeek, int32_t milliseconds,
 374                            int32_t monthLength, UErrorCode& status) const = 0;
 375
 376     /**
 377      * Returns the time zone raw and GMT offset for the given moment
 378      * in time.  Upon return, local-millis = GMT-millis + rawOffset +
 379      * dstOffset.  All computations are performed in the proleptic
 380      * Gregorian calendar.  The default implementation in the TimeZone
 381      * class delegates to the 8-argument getOffset().
 382      *
 383      * @param date moment in time for which to return offsets, in
 384      * units of milliseconds from January 1, 1970 0:00 GMT, either GMT
 385      * time or local wall time, depending on `local'.
 386      * @param local if true, `date' is local wall time; otherwise it
 387      * is in GMT time.
 388      * @param rawOffset output parameter to receive the raw offset, that
 389      * is, the offset not including DST adjustments
 390      * @param dstOffset output parameter to receive the DST offset,
 391      * that is, the offset to be added to `rawOffset' to obtain the
 392      * total offset between local and GMT time. If DST is not in
 393      * effect, this value is zero; otherwise it is a positive value,
 394      * typically one hour.
 395      * @param ec input-output error code
 396      *
 397      * @stable ICU 2.8
 398      */
 399     virtual void getOffset(UDate date, UBool local, int32_t& rawOffset,
 400                            int32_t& dstOffset, UErrorCode& ec) const;
 401
 402     /**
 403      * Sets the TimeZone's raw GMT offset (i.e., the number of milliseconds to add
 404      * to GMT to get local time, before taking daylight savings time into account).
 405      *
 406      * @param offsetMillis  The new raw GMT offset for this time zone.
 407      * @stable ICU 2.0
 408      */
 409     virtual void setRawOffset(int32_t offsetMillis) = 0;
 410
 411     /**
 412      * Returns the TimeZone's raw GMT offset (i.e., the number of milliseconds to add
 413      * to GMT to get local time, before taking daylight savings time into account).
 414      *
 415      * @return   The TimeZone's raw GMT offset.
 416      * @stable ICU 2.0
 417      */
 418     virtual int32_t getRawOffset(void) const = 0;
 419
 420     /**
 421      * Fills in "ID" with the TimeZone's ID.
 422      *
 423      * @param ID  Receives this TimeZone's ID.
 424      * @return    A reference to 'ID'
 425      * @stable ICU 2.0
 426      */
 427     UnicodeString& getID(UnicodeString& ID) const;
 428
 429     /**
 430      * Sets the TimeZone's ID to the specified value.  This doesn't affect any other
 431      * fields (for example, if you say<
 432      * blockquote><pre>
 433      * .     TimeZone* foo = TimeZone::createTimeZone("America/New_York");
 434      * .     foo.setID("America/Los_Angeles");
 435      * </pre>\htmlonly</blockquote>\endhtmlonly
 436      * the time zone's GMT offset and daylight-savings rules don't change to those for
 437      * Los Angeles.  They're still those for New York.  Only the ID has changed.)
 438      *
 439      * @param ID  The new time zone ID.
 440      * @stable ICU 2.0
 441      */
 442     void setID(const UnicodeString& ID);
 443
 444     /**
 445      * Enum for use with getDisplayName
 446      * @stable ICU 2.4
 447      */
 448     enum EDisplayType {
 449         /**
 450          * Selector for short display name
 451          * @stable ICU 2.4
 452          */
 453         SHORT = 1,
 454         /**
 455          * Selector for long display name
 456          * @stable ICU 2.4
 457          */
 458         LONG,
 459         /**
 460          * Selector for short generic display name
 461          * @stable ICU 4.4
 462          */
 463         SHORT_GENERIC,
 464         /**
 465          * Selector for long generic display name
 466          * @stable ICU 4.4
 467          */
 468         LONG_GENERIC,
 469         /**
 470          * Selector for short display name derived
 471          * from time zone offset
 472          * @stable ICU 4.4
 473          */
 474         SHORT_GMT,
 475         /**
 476          * Selector for long display name derived
 477          * from time zone offset
 478          * @stable ICU 4.4
 479          */
 480         LONG_GMT,
 481         /**
 482          * Selector for short display name derived
 483          * from the time zone's fallback name
 484          * @stable ICU 4.4
 485          */
 486         SHORT_COMMONLY_USED,
 487         /**
 488          * Selector for long display name derived
 489          * from the time zone's fallback name
 490          * @stable ICU 4.4
 491          */
 492         GENERIC_LOCATION
 493     };
 494
 495     /**
 496      * Returns a name of this time zone suitable for presentation to the user
 497      * in the default locale.
 498      * This method returns the long name, not including daylight savings.
 499      * If the display name is not available for the locale,
 500      * then this method returns a string in the format
 501      * <code>GMT[+-]hh:mm</code>.
 502      * @param result the human-readable name of this time zone in the default locale.
 503      * @return       A reference to 'result'.
 504      * @stable ICU 2.0
 505      */
 506     UnicodeString& getDisplayName(UnicodeString& result) const;
 507
 508     /**
 509      * Returns a name of this time zone suitable for presentation to the user
 510      * in the specified locale.
 511      * This method returns the long name, not including daylight savings.
 512      * If the display name is not available for the locale,
 513      * then this method returns a string in the format
 514      * <code>GMT[+-]hh:mm</code>.
 515      * @param locale the locale in which to supply the display name.
 516      * @param result the human-readable name of this time zone in the given locale
 517      *               or in the default locale if the given locale is not recognized.
 518      * @return       A reference to 'result'.
 519      * @stable ICU 2.0
 520      */
 521     UnicodeString& getDisplayName(const Locale& locale, UnicodeString& result) const;
 522
 523     /**
 524      * Returns a name of this time zone suitable for presentation to the user
 525      * in the default locale.
 526      * If the display name is not available for the locale,
 527      * then this method returns a string in the format
 528      * <code>GMT[+-]hh:mm</code>.
 529      * @param daylight if true, return the daylight savings name.
 530      * @param style
 531      * @param result the human-readable name of this time zone in the default locale.
 532      * @return       A reference to 'result'.
 533      * @stable ICU 2.0
 534      */
 535     UnicodeString& getDisplayName(UBool daylight, EDisplayType style, UnicodeString& result) const;
 536
 537     /**
 538      * Returns a name of this time zone suitable for presentation to the user
 539      * in the specified locale.
 540      * If the display name is not available for the locale,
 541      * then this method returns a string in the format
 542      * <code>GMT[+-]hh:mm</code>.
 543      * @param daylight if true, return the daylight savings name.
 544      * @param style
 545      * @param locale the locale in which to supply the display name.
 546      * @param result the human-readable name of this time zone in the given locale
 547      *               or in the default locale if the given locale is not recognized.
 548      * @return       A refence to 'result'.
 549      * @stable ICU 2.0
 550      */
 551     UnicodeString& getDisplayName(UBool daylight, EDisplayType style, const Locale& locale, UnicodeString& result) const;
 552
 553     /**
 554      * Queries if this time zone uses daylight savings time.
 555      * @return true if this time zone uses daylight savings time,
 556      * false, otherwise.
 557      * @stable ICU 2.0
 558      */
 559     virtual UBool useDaylightTime(void) const = 0;
 560
 561     /**
 562      * Queries if the given date is in daylight savings time in
 563      * this time zone.
 564      * This method is wasteful since it creates a new GregorianCalendar and
 565      * deletes it each time it is called. This is a deprecated method
 566      * and provided only for Java compatibility.
 567      *
 568      * @param date the given UDate.
 569      * @param status Output param filled in with success/error code.
 570      * @return true if the given date is in daylight savings time,
 571      * false, otherwise.
 572      * @deprecated ICU 2.4. Use Calendar::inDaylightTime() instead.
 573      */
 574     virtual UBool inDaylightTime(UDate date, UErrorCode& status) const = 0;
 575
 576     /**
 577      * Returns true if this zone has the same rule and offset as another zone.
 578      * That is, if this zone differs only in ID, if at all.
 579      * @param other the <code>TimeZone</code> object to be compared with
 580      * @return true if the given zone is the same as this one,
 581      * with the possible exception of the ID
 582      * @stable ICU 2.0
 583      */
 584     virtual UBool hasSameRules(const TimeZone& other) const;
 585
 586     /**
 587      * Clones TimeZone objects polymorphically. Clients are responsible for deleting
 588      * the TimeZone object cloned.
 589      *
 590      * @return   A new copy of this TimeZone object.
 591      * @stable ICU 2.0
 592      */
 593     virtual TimeZone* clone(void) const = 0;
 594
 595     /**
 596      * Return the class ID for this class.  This is useful only for
 597      * comparing to a return value from getDynamicClassID().
 598      * @return The class ID for all objects of this class.
 599      * @stable ICU 2.0
 600      */
 601     static UClassID U_EXPORT2 getStaticClassID(void);
 602
 603     /**
 604      * Returns a unique class ID POLYMORPHICALLY. This method is to
 605      * implement a simple version of RTTI, since not all C++ compilers support genuine
 606      * RTTI. Polymorphic operator==() and clone() methods call this method.
 607      * <P>
 608      * Concrete subclasses of TimeZone must use the UOBJECT_DEFINE_RTTI_IMPLEMENTATION
 609      *  macro from uobject.h in their implementation to provide correct RTTI information.
 610      * @return   The class ID for this object. All objects of a given class have the
 611      *           same class ID. Objects of other classes have different class IDs.
 612      * @stable ICU 2.0
 613      */
 614     virtual UClassID getDynamicClassID(void) const = 0;
 615
 616     /**
 617      * Returns the amount of time to be added to local standard time
 618      * to get local wall clock time.
 619      * <p>
 620      * The default implementation always returns 3600000 milliseconds
 621      * (i.e., one hour) if this time zone observes Daylight Saving
 622      * Time. Otherwise, 0 (zero) is returned.
 623      * <p>
 624      * If an underlying TimeZone implementation subclass supports
 625      * historical Daylight Saving Time changes, this method returns
 626      * the known latest daylight saving value.
 627      *
 628      * @return the amount of saving time in milliseconds
 629      * @stable ICU 3.6
 630      */
 631     virtual int32_t getDSTSavings() const;
 632
 633 protected:
 634
 635     /**
 636      * Default constructor.  ID is initialized to the empty string.
 637      * @stable ICU 2.0
 638      */
 639     TimeZone();
 640
 641     /**
 642      * Construct a TimeZone with a given ID.
 643      * @param id a system time zone ID
 644      * @stable ICU 2.0
 645      */
 646     TimeZone(const UnicodeString &id);
 647
 648     /**
 649      * Copy constructor.
 650      * @param source the object to be copied.
 651      * @stable ICU 2.0
 652      */
 653     TimeZone(const TimeZone& source);
 654
 655     /**
 656      * Default assignment operator.
 657      * @param right the object to be copied.
 658      * @stable ICU 2.0
 659      */
 660     TimeZone& operator=(const TimeZone& right);
 661
 662     /**
 663      * Utility function. For internally loading rule data.
 664      * @param top Top resource bundle for tz data
 665      * @param ruleid ID of rule to load
 666      * @param oldbundle Old bundle to reuse or NULL
 667      * @param status Status parameter
 668      * @return either a new bundle or *oldbundle
 669      * @internal
 670      */
 671     static UResourceBundle* loadRule(const UResourceBundle* top, const UnicodeString& ruleid, UResourceBundle* oldbundle, UErrorCode&status);
 672
 673 private:
 674     friend class ZoneMeta;
 675
 676
 677     static TimeZone*        createCustomTimeZone(const UnicodeString&); // Creates a time zone based on the string.
 678
 679     /**
 680      * Resolve a link in Olson tzdata.  When the given id is known and it's not a link,
 681      * the id itself is returned.  When the given id is known and it is a link, then
 682      * dereferenced zone id is returned.  When the given id is unknown, then it returns
 683      * NULL.
 684      * @param id zone id string
 685      * @return the dereferenced zone or NULL
 686      */
 687     static const UChar* dereferOlsonLink(const UnicodeString& id);
 688
 689     /**
 690      * Returns the region code associated with the given zone.
 691      * @param id zone id string
 692      * @return the region associated with the given zone
 693      */
 694     static const UChar* getRegion(const UnicodeString& id);
 695
 696     /**
 697      * Parses the given custom time zone identifier
 698      * @param id id A string of the form GMT[+-]hh:mm, GMT[+-]hhmm, or
 699      * GMT[+-]hh.
 700      * @param sign Receves parsed sign, 1 for positive, -1 for negative.
 701      * @param hour Receives parsed hour field
 702      * @param minute Receives parsed minute field
 703      * @param second Receives parsed second field
 704      * @return Returns TRUE when the given custom id is valid.
 705      */
 706     static UBool parseCustomID(const UnicodeString& id, int32_t& sign, int32_t& hour,
 707         int32_t& min, int32_t& sec);
 708
 709     /**
 710      * Parse a custom time zone identifier and return the normalized
 711      * custom time zone identifier for the given custom id string.
 712      * @param id a string of the form GMT[+-]hh:mm, GMT[+-]hhmm, or
 713      * GMT[+-]hh.
 714      * @param normalized Receives the normalized custom ID
 715      * @param status Receives the status.  When the input ID string is invalid,
 716      * U_ILLEGAL_ARGUMENT_ERROR is set.
 717      * @return The normalized custom id string.
 718     */
 719     static UnicodeString& getCustomID(const UnicodeString& id, UnicodeString& normalized,
 720         UErrorCode& status);
 721
 722     /**
 723      * Returns the normalized custome time zone ID for the given offset fields.
 724      * @param hour offset hours
 725      * @param min offset minutes
 726      * @param sec offset seconds
 727      * @param netative sign of the offset, TRUE for negative offset.
 728      * @param id Receves the format result (normalized custom ID)
 729      * @return The reference to id
 730      */
 731     static UnicodeString& formatCustomID(int32_t hour, int32_t min, int32_t sec,
 732         UBool negative, UnicodeString& id);
 733
 734     /**
 735      * Responsible for setting up DEFAULT_ZONE.  Uses routines in TPlatformUtilities
 736      * (i.e., platform-specific calls) to get the current system time zone.  Failing
 737      * that, uses the platform-specific default time zone.  Failing that, uses GMT.
 738      */
 739     static void             initDefault(void);
 740
 741     // See source file for documentation
 742     /**
 743      * Lookup the given name in our system zone table.  If found,
 744      * instantiate a new zone of that name and return it.  If not
 745      * found, return 0.
 746      * @param name tthe given name of a system time zone.
 747      * @return the TimeZone indicated by the 'name'.
 748      */
 749     static TimeZone*        createSystemTimeZone(const UnicodeString& name);
 750
 751     UnicodeString           fID;    // this time zone's ID
 752
 753 };
 754
 755
 756 // -------------------------------------
 757
 758 inline UnicodeString&
 759 TimeZone::getID(UnicodeString& ID) const
 760 {
 761     ID = fID;
 762     return ID;
 763 }
 764
 765 // -------------------------------------
 766
 767 inline void
 768 TimeZone::setID(const UnicodeString& ID)
 769 {
 770     fID = ID;
 771 }
 772 U_NAMESPACE_END
 773
 774 #endif /* #if !UCONFIG_NO_FORMATTING */
 775
 776 #endif //_TIMEZONE
 777 //eof