1 /*************************************************************************
2 * Copyright (c) 1997-2012, 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 #include "unicode/ucal.h"
43
44 U_NAMESPACE_BEGIN
45
46 class StringEnumeration;
47
48 /**
49 *
50 * <code>TimeZone</code> represents a time zone offset, and also figures out daylight
51 * savings.
52 *
53 * <p>
54 * Typically, you get a <code>TimeZone</code> using <code>createDefault</code>
55 * which creates a <code>TimeZone</code> based on the time zone where the program
56 * is running. For example, for a program running in Japan, <code>createDefault</code>
57 * creates a <code>TimeZone</code> object based on Japanese Standard Time.
58 *
59 * <p>
60 * You can also get a <code>TimeZone</code> using <code>createTimeZone</code> along
61 * with a time zone ID. For instance, the time zone ID for the US Pacific
62 * Time zone is "America/Los_Angeles". So, you can get a Pacific Time <code>TimeZone</code> object
63 * with:
64 * \htmlonly<blockquote>\endhtmlonly
65 * <pre>
66 * TimeZone *tz = TimeZone::createTimeZone("America/Los_Angeles");
67 * </pre>
68 * \htmlonly</blockquote>\endhtmlonly
69 * You can use <code>getAvailableIDs</code> method to iterate through
70 * all the supported time zone IDs, or getCanonicalID method to check
71 * if a time zone ID is supported or not. You can then choose a
72 * supported ID to get a <code>TimeZone</code>.
73 * If the time zone you want is not represented by one of the
74 * supported IDs, then you can create a custom time zone ID with
75 * the following syntax:
76 *
77 * \htmlonly<blockquote>\endhtmlonly
78 * <pre>
79 * GMT[+|-]hh[[:]mm]
80 * </pre>
81 * \htmlonly</blockquote>\endhtmlonly
82 *
83 * For example, you might specify GMT+14:00 as a custom
84 * time zone ID. The <code>TimeZone</code> that is returned
85 * when you specify a custom time zone ID uses the specified
86 * offset from GMT(=UTC) and does not observe daylight saving
87 * time. For example, you might specify GMT+14:00 as a custom
88 * time zone ID to create a TimeZone representing 14 hours ahead
89 * of GMT (with no daylight saving time). In addition,
90 * <code>getCanonicalID</code> can also be used to
91 * normalize a custom time zone ID.
92 *
93 * TimeZone is an abstract class representing a time zone. A TimeZone is needed for
94 * Calendar to produce local time for a particular time zone. A TimeZone comprises
95 * three basic pieces of information:
96 * <ul>
97 * <li>A time zone offset; that, is the number of milliseconds to add or subtract
98 * from a time expressed in terms of GMT to convert it to the same time in that
99 * time zone (without taking daylight savings time into account).</li>
100 * <li>Logic necessary to take daylight savings time into account if daylight savings
101 * time is observed in that time zone (e.g., the days and hours on which daylight
102 * savings time begins and ends).</li>
103 * <li>An ID. This is a text string that uniquely identifies the time zone.</li>
104 * </ul>
105 *
106 * (Only the ID is actually implemented in TimeZone; subclasses of TimeZone may handle
107 * daylight savings time and GMT offset in different ways. Currently we have the following
108 * TimeZone subclasses: RuleBasedTimeZone, SimpleTimeZone, and VTimeZone.)
109 * <P>
110 * The TimeZone class contains a static list containing a TimeZone object for every
111 * combination of GMT offset and daylight-savings time rules currently in use in the
112 * world, each with a unique ID. Each ID consists of a region (usually a continent or
113 * ocean) and a city in that region, separated by a slash, (for example, US Pacific
114 * Time is "America/Los_Angeles.") Because older versions of this class used
115 * three- or four-letter abbreviations instead, there is also a table that maps the older
116 * abbreviations to the newer ones (for example, "PST" maps to "America/Los_Angeles").
117 * Anywhere the API requires an ID, you can use either form.
118 * <P>
119 * To create a new TimeZone, you call the factory function TimeZone::createTimeZone()
120 * and pass it a time zone ID. You can use the createEnumeration() function to
121 * obtain a list of all the time zone IDs recognized by createTimeZone().
122 * <P>
123 * You can also use TimeZone::createDefault() to create a TimeZone. This function uses
124 * platform-specific APIs to produce a TimeZone for the time zone corresponding to
125 * the client's computer's physical location. For example, if you're in Japan (assuming
126 * your machine is set up correctly), TimeZone::createDefault() will return a TimeZone
127 * for Japanese Standard Time ("Asia/Tokyo").
128 */
129 class U_I18N_API TimeZone : public UObject {
130 public:
131 /**
132 * @stable ICU 2.0
133 */
134 virtual ~TimeZone();
135
136 #ifndef U_HIDE_DRAFT_API
137 /**
138 * Returns the "unknown" time zone.
139 * It behaves like the GMT/UTC time zone but has the
140 * <code>UCAL_UNKNOWN_ZONE_ID</code> = "Etc/Unknown".
141 * createTimeZone() returns a mutable clone of this time zone if the input ID is not recognized.
142 *
143 * @return the "unknown" time zone.
144 * @see UCAL_UNKNOWN_ZONE_ID
145 * @see createTimeZone
146 * @see getGMT
147 * @draft ICU 49
148 */
149 static const TimeZone& U_EXPORT2 getUnknown();
150 #endif /* U_HIDE_DRAFT_API */
151
152 /**
153 * The GMT (=UTC) time zone has a raw offset of zero and does not use daylight
154 * savings time. This is a commonly used time zone.
155 *
156 * <p>Note: For backward compatibility reason, the ID used by the time
157 * zone returned by this method is "GMT", although the ICU's canonical
158 * ID for the GMT time zone is "Etc/GMT".
159 *
160 * @return the GMT/UTC time zone.
161 * @see getUnknown
162 * @stable ICU 2.0
163 */
164 static const TimeZone* U_EXPORT2 getGMT(void);
165
166 /**
167 * Creates a <code>TimeZone</code> for the given ID.
168 * @param ID the ID for a <code>TimeZone</code>, such as "America/Los_Angeles",
169 * or a custom ID such as "GMT-8:00".
170 * @return the specified <code>TimeZone</code>, or a mutable clone of getUnknown()
171 * if the given ID cannot be understood or if the given ID is "Etc/Unknown".
172 * The return result is guaranteed to be non-NULL.
173 * If you require that the specific zone asked for be returned,
174 * compare the result with getUnknown() or check the ID of the return result.
175 * @stable ICU 2.0
176 */
177 static TimeZone* U_EXPORT2 createTimeZone(const UnicodeString& ID);
178
179 /**
180 * Returns an enumeration over system time zone IDs with the given
181 * filter conditions.
182 * @param zoneType The system time zone type.
183 * @param region The ISO 3166 two-letter country code or UN M.49
184 * three-digit area code. When NULL, no filtering
185 * done by region.
186 * @param rawOffset An offset from GMT in milliseconds, ignoring
187 * the effect of daylight savings time, if any.
188 * When NULL, no filtering done by zone offset.
189 * @param ec Output param to filled in with a success or
190 * an error.
191 * @return an enumeration object, owned by the caller.
192 * @stable ICU 4.8
193 */
194 static StringEnumeration* U_EXPORT2 createTimeZoneIDEnumeration(
195 USystemTimeZoneType zoneType,
196 const char* region,
197 const int32_t* rawOffset,
198 UErrorCode& ec);
199
200 /**
201 * Returns an enumeration over all recognized time zone IDs. (i.e.,
202 * all strings that createTimeZone() accepts)
203 *
204 * @return an enumeration object, owned by the caller.
205 * @stable ICU 2.4
206 */
207 static StringEnumeration* U_EXPORT2 createEnumeration();
208
209 /**
210 * Returns an enumeration over time zone IDs with a given raw
211 * offset from GMT. There may be several times zones with the
212 * same GMT offset that differ in the way they handle daylight
213 * savings time. For example, the state of Arizona doesn't
214 * observe daylight savings time. If you ask for the time zone
215 * IDs corresponding to GMT-7:00, you'll get back an enumeration
216 * over two time zone IDs: "America/Denver," which corresponds to
217 * Mountain Standard Time in the winter and Mountain Daylight Time
218 * in the summer, and "America/Phoenix", which corresponds to
219 * Mountain Standard Time year-round, even in the summer.
220 *
221 * @param rawOffset an offset from GMT in milliseconds, ignoring
222 * the effect of daylight savings time, if any
223 * @return an enumeration object, owned by the caller
224 * @stable ICU 2.4
225 */
226 static StringEnumeration* U_EXPORT2 createEnumeration(int32_t rawOffset);
227
228 /**
229 * Returns an enumeration over time zone IDs associated with the
230 * given country. Some zones are affiliated with no country
231 * (e.g., "UTC"); these may also be retrieved, as a group.
232 *
233 * @param country The ISO 3166 two-letter country code, or NULL to
234 * retrieve zones not affiliated with any country.
235 * @return an enumeration object, owned by the caller
236 * @stable ICU 2.4
237 */
238 static StringEnumeration* U_EXPORT2 createEnumeration(const char* country);
239
240 /**
241 * Returns the number of IDs in the equivalency group that
242 * includes the given ID. An equivalency group contains zones
243 * that have the same GMT offset and rules.
244 *
245 * <p>The returned count includes the given ID; it is always >= 1.
246 * The given ID must be a system time zone. If it is not, returns
247 * zero.
248 * @param id a system time zone ID
249 * @return the number of zones in the equivalency group containing
250 * 'id', or zero if 'id' is not a valid system ID
251 * @see #getEquivalentID
252 * @stable ICU 2.0
253 */
254 static int32_t U_EXPORT2 countEquivalentIDs(const UnicodeString& id);
255
256 /**
257 * Returns an ID in the equivalency group that
258 * includes the given ID. An equivalency group contains zones
259 * that have the same GMT offset and rules.
260 *
261 * <p>The given index must be in the range 0..n-1, where n is the
262 * value returned by <code>countEquivalentIDs(id)</code>. For
263 * some value of 'index', the returned value will be equal to the
264 * given id. If the given id is not a valid system time zone, or
265 * if 'index' is out of range, then returns an empty string.
266 * @param id a system time zone ID
267 * @param index a value from 0 to n-1, where n is the value
268 * returned by <code>countEquivalentIDs(id)</code>
269 * @return the ID of the index-th zone in the equivalency group
270 * containing 'id', or an empty string if 'id' is not a valid
271 * system ID or 'index' is out of range
272 * @see #countEquivalentIDs
273 * @stable ICU 2.0
274 */
275 static const UnicodeString U_EXPORT2 getEquivalentID(const UnicodeString& id,
276 int32_t index);
277
278 /**
279 * Creates a new copy of the default TimeZone for this host. Unless the default time
280 * zone has already been set using adoptDefault() or setDefault(), the default is
281 * determined by querying the system using methods in TPlatformUtilities. If the
282 * system routines fail, or if they specify a TimeZone or TimeZone offset which is not
283 * recognized, the TimeZone indicated by the ID kLastResortID is instantiated
284 * and made the default.
285 *
286 * @return A default TimeZone. Clients are responsible for deleting the time zone
287 * object returned.
288 * @stable ICU 2.0
289 */
290 static TimeZone* U_EXPORT2 createDefault(void);
291
292 /**
293 * Sets the default time zone (i.e., what's returned by createDefault()) to be the
294 * specified time zone. If NULL is specified for the time zone, the default time
295 * zone is set to the default host time zone. This call adopts the TimeZone object
296 * passed in; the clent is no longer responsible for deleting it.
297 *
298 * @param zone A pointer to the new TimeZone object to use as the default.
299 * @stable ICU 2.0
300 */
301 static void U_EXPORT2 adoptDefault(TimeZone* zone);
302
303 #ifndef U_HIDE_SYSTEM_API
304 /**
305 * Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted;
306 * the caller remains responsible for deleting it.
307 *
308 * @param zone The given timezone.
309 * @system
310 * @stable ICU 2.0
311 */
312 static void U_EXPORT2 setDefault(const TimeZone& zone);
313 #endif /* U_HIDE_SYSTEM_API */
314
315 /**
316 * Returns the timezone data version currently used by ICU.
317 * @param status Output param to filled in with a success or an error.
318 * @return the version string, such as "2007f"
319 * @stable ICU 3.8
320 */
321 static const char* U_EXPORT2 getTZDataVersion(UErrorCode& status);
322
323 /**
324 * Returns the canonical system timezone ID or the normalized
325 * custom time zone ID for the given time zone ID.
326 * @param id The input time zone ID to be canonicalized.
327 * @param canonicalID Receives the canonical system time zone ID
328 * or the custom time zone ID in normalized format.
329 * @param status Recevies the status. When the given time zone ID
330 * is neither a known system time zone ID nor a
331 * valid custom time zone ID, U_ILLEGAL_ARGUMENT_ERROR
332 * is set.
333 * @return A reference to the result.
334 * @stable ICU 4.0
335 */
336 static UnicodeString& U_EXPORT2 getCanonicalID(const UnicodeString& id,
337 UnicodeString& canonicalID, UErrorCode& status);
338
339 /**
340 * Returns the canonical system time zone ID or the normalized
341 * custom time zone ID for the given time zone ID.
342 * @param id The input time zone ID to be canonicalized.
343 * @param canonicalID Receives the canonical system time zone ID
344 * or the custom time zone ID in normalized format.
345 * @param isSystemID Receives if the given ID is a known system
346 * time zone ID.
347 * @param status Recevies the status. When the given time zone ID
348 * is neither a known system time zone ID nor a
349 * valid custom time zone ID, U_ILLEGAL_ARGUMENT_ERROR
350 * is set.
351 * @return A reference to the result.
352 * @stable ICU 4.0
353 */
354 static UnicodeString& U_EXPORT2 getCanonicalID(const UnicodeString& id,
355 UnicodeString& canonicalID, UBool& isSystemID, UErrorCode& status);
356
357 /**
358 * Returns true if the two TimeZones are equal. (The TimeZone version only compares
359 * IDs, but subclasses are expected to also compare the fields they add.)
360 *
361 * @param that The TimeZone object to be compared with.
362 * @return True if the given TimeZone is equal to this TimeZone; false
363 * otherwise.
364 * @stable ICU 2.0
365 */
366 virtual UBool operator==(const TimeZone& that) const;
367
368 /**
369 * Returns true if the two TimeZones are NOT equal; that is, if operator==() returns
370 * false.
371 *
372 * @param that The TimeZone object to be compared with.
373 * @return True if the given TimeZone is not equal to this TimeZone; false
374 * otherwise.
375 * @stable ICU 2.0
376 */
377 UBool operator!=(const TimeZone& that) const {return !operator==(that);}
378
379 /**
380 * Returns the TimeZone's adjusted GMT offset (i.e., the number of milliseconds to add
381 * to GMT to get local time in this time zone, taking daylight savings time into
382 * account) as of a particular reference date. The reference date is used to determine
383 * whether daylight savings time is in effect and needs to be figured into the offset
384 * that is returned (in other words, what is the adjusted GMT offset in this time zone
385 * at this particular date and time?). For the time zones produced by createTimeZone(),
386 * the reference data is specified according to the Gregorian calendar, and the date
387 * and time fields are local standard time.
388 *
389 * <p>Note: Don't call this method. Instead, call the getOffset(UDate...) overload,
390 * which returns both the raw and the DST offset for a given time. This method
391 * is retained only for backward compatibility.
392 *
393 * @param era The reference date's era
394 * @param year The reference date's year
395 * @param month The reference date's month (0-based; 0 is January)
396 * @param day The reference date's day-in-month (1-based)
397 * @param dayOfWeek The reference date's day-of-week (1-based; 1 is Sunday)
398 * @param millis The reference date's milliseconds in day, local standard time
399 * @param status Output param to filled in with a success or an error.
400 * @return The offset in milliseconds to add to GMT to get local time.
401 * @stable ICU 2.0
402 */
403 virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day,
404 uint8_t dayOfWeek, int32_t millis, UErrorCode& status) const = 0;
405
406 /**
407 * Gets the time zone offset, for current date, modified in case of
408 * daylight savings. This is the offset to add *to* UTC to get local time.
409 *
410 * <p>Note: Don't call this method. Instead, call the getOffset(UDate...) overload,
411 * which returns both the raw and the DST offset for a given time. This method
412 * is retained only for backward compatibility.
413 *
414 * @param era the era of the given date.
415 * @param year the year in the given date.
416 * @param month the month in the given date.
417 * Month is 0-based. e.g., 0 for January.
418 * @param day the day-in-month of the given date.
419 * @param dayOfWeek the day-of-week of the given date.
420 * @param milliseconds the millis in day in <em>standard</em> local time.
421 * @param monthLength the length of the given month in days.
422 * @param status Output param to filled in with a success or an error.
423 * @return the offset to add *to* GMT to get local time.
424 * @stable ICU 2.0
425 */
426 virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day,
427 uint8_t dayOfWeek, int32_t milliseconds,
428 int32_t monthLength, UErrorCode& status) const = 0;
429
430 /**
431 * Returns the time zone raw and GMT offset for the given moment
432 * in time. Upon return, local-millis = GMT-millis + rawOffset +
433 * dstOffset. All computations are performed in the proleptic
434 * Gregorian calendar. The default implementation in the TimeZone
435 * class delegates to the 8-argument getOffset().
436 *
437 * @param date moment in time for which to return offsets, in
438 * units of milliseconds from January 1, 1970 0:00 GMT, either GMT
439 * time or local wall time, depending on `local'.
440 * @param local if true, `date' is local wall time; otherwise it
441 * is in GMT time.
442 * @param rawOffset output parameter to receive the raw offset, that
443 * is, the offset not including DST adjustments
444 * @param dstOffset output parameter to receive the DST offset,
445 * that is, the offset to be added to `rawOffset' to obtain the
446 * total offset between local and GMT time. If DST is not in
447 * effect, this value is zero; otherwise it is a positive value,
448 * typically one hour.
449 * @param ec input-output error code
450 *
451 * @stable ICU 2.8
452 */
453 virtual void getOffset(UDate date, UBool local, int32_t& rawOffset,
454 int32_t& dstOffset, UErrorCode& ec) const;
455
456 /**
457 * Sets the TimeZone's raw GMT offset (i.e., the number of milliseconds to add
458 * to GMT to get local time, before taking daylight savings time into account).
459 *
460 * @param offsetMillis The new raw GMT offset for this time zone.
461 * @stable ICU 2.0
462 */
463 virtual void setRawOffset(int32_t offsetMillis) = 0;
464
465 /**
466 * Returns the TimeZone's raw GMT offset (i.e., the number of milliseconds to add
467 * to GMT to get local time, before taking daylight savings time into account).
468 *
469 * @return The TimeZone's raw GMT offset.
470 * @stable ICU 2.0
471 */
472 virtual int32_t getRawOffset(void) const = 0;
473
474 /**
475 * Fills in "ID" with the TimeZone's ID.
476 *
477 * @param ID Receives this TimeZone's ID.
478 * @return A reference to 'ID'
479 * @stable ICU 2.0
480 */
481 UnicodeString& getID(UnicodeString& ID) const;
482
483 /**
484 * Sets the TimeZone's ID to the specified value. This doesn't affect any other
485 * fields (for example, if you say<
486 * blockquote><pre>
487 * . TimeZone* foo = TimeZone::createTimeZone("America/New_York");
488 * . foo.setID("America/Los_Angeles");
489 * </pre>\htmlonly</blockquote>\endhtmlonly
490 * the time zone's GMT offset and daylight-savings rules don't change to those for
491 * Los Angeles. They're still those for New York. Only the ID has changed.)
492 *
493 * @param ID The new time zone ID.
494 * @stable ICU 2.0
495 */
496 void setID(const UnicodeString& ID);
497
498 /**
499 * Enum for use with getDisplayName
500 * @stable ICU 2.4
501 */
502 enum EDisplayType {
503 /**
504 * Selector for short display name
505 * @stable ICU 2.4
506 */
507 SHORT = 1,
508 /**
509 * Selector for long display name
510 * @stable ICU 2.4
511 */
512 LONG,
513 /**
514 * Selector for short generic display name
515 * @stable ICU 4.4
516 */
517 SHORT_GENERIC,
518 /**
519 * Selector for long generic display name
520 * @stable ICU 4.4
521 */
522 LONG_GENERIC,
523 /**
524 * Selector for short display name derived
525 * from time zone offset
526 * @stable ICU 4.4
527 */
528 SHORT_GMT,
529 /**
530 * Selector for long display name derived
531 * from time zone offset
532 * @stable ICU 4.4
533 */
534 LONG_GMT,
535 /**
536 * Selector for short display name derived
537 * from the time zone's fallback name
538 * @stable ICU 4.4
539 */
540 SHORT_COMMONLY_USED,
541 /**
542 * Selector for long display name derived
543 * from the time zone's fallback name
544 * @stable ICU 4.4
545 */
546 GENERIC_LOCATION
547 };
548
549 /**
550 * Returns a name of this time zone suitable for presentation to the user
551 * in the default locale.
552 * This method returns the long name, not including daylight savings.
553 * If the display name is not available for the locale,
554 * then this method returns a string in the format
555 * <code>GMT[+-]hh:mm</code>.
556 * @param result the human-readable name of this time zone in the default locale.
557 * @return A reference to 'result'.
558 * @stable ICU 2.0
559 */
560 UnicodeString& getDisplayName(UnicodeString& result) const;
561
562 /**
563 * Returns a name of this time zone suitable for presentation to the user
564 * in the specified locale.
565 * This method returns the long name, not including daylight savings.
566 * If the display name is not available for the locale,
567 * then this method returns a string in the format
568 * <code>GMT[+-]hh:mm</code>.
569 * @param locale the locale in which to supply the display name.
570 * @param result the human-readable name of this time zone in the given locale
571 * or in the default locale if the given locale is not recognized.
572 * @return A reference to 'result'.
573 * @stable ICU 2.0
574 */
575 UnicodeString& getDisplayName(const Locale& locale, UnicodeString& result) const;
576
577 /**
578 * Returns a name of this time zone suitable for presentation to the user
579 * in the default locale.
580 * If the display name is not available for the locale,
581 * then this method returns a string in the format
582 * <code>GMT[+-]hh:mm</code>.
583 * @param daylight if true, return the daylight savings name.
584 * @param style
585 * @param result the human-readable name of this time zone in the default locale.
586 * @return A reference to 'result'.
587 * @stable ICU 2.0
588 */
589 UnicodeString& getDisplayName(UBool daylight, EDisplayType style, UnicodeString& result) const;
590
591 /**
592 * Returns a name of this time zone suitable for presentation to the user
593 * in the specified locale.
594 * If the display name is not available for the locale,
595 * then this method returns a string in the format
596 * <code>GMT[+-]hh:mm</code>.
597 * @param daylight if true, return the daylight savings name.
598 * @param style
599 * @param locale the locale in which to supply the display name.
600 * @param result the human-readable name of this time zone in the given locale
601 * or in the default locale if the given locale is not recognized.
602 * @return A refence to 'result'.
603 * @stable ICU 2.0
604 */
605 UnicodeString& getDisplayName(UBool daylight, EDisplayType style, const Locale& locale, UnicodeString& result) const;
606
607 /**
608 * Queries if this time zone uses daylight savings time.
609 * @return true if this time zone uses daylight savings time,
610 * false, otherwise.
611 * <p><strong>Note:</strong>The default implementation of
612 * ICU TimeZone uses the tz database, which supports historic
613 * rule changes, for system time zones. With the implementation,
614 * there are time zones that used daylight savings time in the
615 * past, but no longer used currently. For example, Asia/Tokyo has
616 * never used daylight savings time since 1951. Most clients would
617 * expect that this method to return <code>FALSE</code> for such case.
618 * The default implementation of this method returns <code>TRUE</code>
619 * when the time zone uses daylight savings time in the current
620 * (Gregorian) calendar year.
621 * <p>In Java 7, <code>observesDaylightTime()</code> was added in
622 * addition to <code>useDaylightTime()</code>. In Java, <code>useDaylightTime()</code>
623 * only checks if daylight saving time is observed by the last known
624 * rule. This specification might not be what most users would expect
625 * if daylight saving time is currently observed, but not scheduled
626 * in future. In this case, Java's <code>userDaylightTime()</code> returns
627 * <code>false</code>. To resolve the issue, Java 7 added <code>observesDaylightTime()</code>,
628 * which takes the current rule into account. The method <code>observesDaylightTime()</code>
629 * was added in ICU4J for supporting API signature compatibility with JDK.
630 * In general, ICU4C also provides JDK compatible methods, but the current
631 * implementation <code>userDaylightTime()</code> serves the purpose
632 * (takes the current rule into account), <code>observesDaylightTime()</code>
633 * is not added in ICU4C. In addition to <code>useDaylightTime()</code>, ICU4C
634 * <code>BasicTimeZone</code> class (Note that <code>TimeZone::createTimeZone(const UnicodeString &ID)</code>
635 * always returns a <code>BasicTimeZone</code>) provides a series of methods allowing
636 * historic and future time zone rule iteration, so you can check if daylight saving
637 * time is observed or not within a given period.
638 *
639 * @stable ICU 2.0
640 */
641 virtual UBool useDaylightTime(void) const = 0;
642
643 /**
644 * Queries if the given date is in daylight savings time in
645 * this time zone.
646 * This method is wasteful since it creates a new GregorianCalendar and
647 * deletes it each time it is called. This is a deprecated method
648 * and provided only for Java compatibility.
649 *
650 * @param date the given UDate.
651 * @param status Output param filled in with success/error code.
652 * @return true if the given date is in daylight savings time,
653 * false, otherwise.
654 * @deprecated ICU 2.4. Use Calendar::inDaylightTime() instead.
655 */
656 virtual UBool inDaylightTime(UDate date, UErrorCode& status) const = 0;
657
658 /**
659 * Returns true if this zone has the same rule and offset as another zone.
660 * That is, if this zone differs only in ID, if at all.
661 * @param other the <code>TimeZone</code> object to be compared with
662 * @return true if the given zone is the same as this one,
663 * with the possible exception of the ID
664 * @stable ICU 2.0
665 */
666 virtual UBool hasSameRules(const TimeZone& other) const;
667
668 /**
669 * Clones TimeZone objects polymorphically. Clients are responsible for deleting
670 * the TimeZone object cloned.
671 *
672 * @return A new copy of this TimeZone object.
673 * @stable ICU 2.0
674 */
675 virtual TimeZone* clone(void) const = 0;
676
677 /**
678 * Return the class ID for this class. This is useful only for
679 * comparing to a return value from getDynamicClassID().
680 * @return The class ID for all objects of this class.
681 * @stable ICU 2.0
682 */
683 static UClassID U_EXPORT2 getStaticClassID(void);
684
685 /**
686 * Returns a unique class ID POLYMORPHICALLY. This method is to
687 * implement a simple version of RTTI, since not all C++ compilers support genuine
688 * RTTI. Polymorphic operator==() and clone() methods call this method.
689 * <P>
690 * Concrete subclasses of TimeZone must use the UOBJECT_DEFINE_RTTI_IMPLEMENTATION
691 * macro from uobject.h in their implementation to provide correct RTTI information.
692 * @return The class ID for this object. All objects of a given class have the
693 * same class ID. Objects of other classes have different class IDs.
694 * @stable ICU 2.0
695 */
696 virtual UClassID getDynamicClassID(void) const = 0;
697
698 /**
699 * Returns the amount of time to be added to local standard time
700 * to get local wall clock time.
701 * <p>
702 * The default implementation always returns 3600000 milliseconds
703 * (i.e., one hour) if this time zone observes Daylight Saving
704 * Time. Otherwise, 0 (zero) is returned.
705 * <p>
706 * If an underlying TimeZone implementation subclass supports
707 * historical Daylight Saving Time changes, this method returns
708 * the known latest daylight saving value.
709 *
710 * @return the amount of saving time in milliseconds
711 * @stable ICU 3.6
712 */
713 virtual int32_t getDSTSavings() const;
714
715 /**
716 * Gets the region code associated with the given
717 * system time zone ID. The region code is either ISO 3166
718 * 2-letter country code or UN M.49 3-digit area code.
719 * When the time zone is not associated with a specific location,
720 * for example - "Etc/UTC", "EST5EDT", then this method returns
721 * "001" (UN M.49 area code for World).
722 *
723 * @param id The system time zone ID.
724 * @param region Output buffer for receiving the region code.
725 * @param capacity The size of the output buffer.
726 * @param status Receives the status. When the given time zone ID
727 * is not a known system time zone ID,
728 * U_ILLEGAL_ARGUMENT_ERROR is set.
729 * @return The length of the output region code.
730 * @stable ICU 4.8
731 */
732 static int32_t U_EXPORT2 getRegion(const UnicodeString& id,
733 char *region, int32_t capacity, UErrorCode& status);
734
735 protected:
736
737 /**
738 * Default constructor. ID is initialized to the empty string.
739 * @stable ICU 2.0
740 */
741 TimeZone();
742
743 /**
744 * Construct a TimeZone with a given ID.
745 * @param id a system time zone ID
746 * @stable ICU 2.0
747 */
748 TimeZone(const UnicodeString &id);
749
750 /**
751 * Copy constructor.
752 * @param source the object to be copied.
753 * @stable ICU 2.0
754 */
755 TimeZone(const TimeZone& source);
756
757 /**
758 * Default assignment operator.
759 * @param right the object to be copied.
760 * @stable ICU 2.0
761 */
762 TimeZone& operator=(const TimeZone& right);
763
764 #ifndef U_HIDE_INTERNAL_API
765 /**
766 * Utility function. For internally loading rule data.
767 * @param top Top resource bundle for tz data
768 * @param ruleid ID of rule to load
769 * @param oldbundle Old bundle to reuse or NULL
770 * @param status Status parameter
771 * @return either a new bundle or *oldbundle
772 * @internal
773 */
774 static UResourceBundle* loadRule(const UResourceBundle* top, const UnicodeString& ruleid, UResourceBundle* oldbundle, UErrorCode&status);
775 #endif /* U_HIDE_INTERNAL_API */
776
777 private:
778 friend class ZoneMeta;
779
780
781 static TimeZone* createCustomTimeZone(const UnicodeString&); // Creates a time zone based on the string.
782
783 /**
784 * Finds the given ID in the Olson tzdata. If the given ID is found in the tzdata,
785 * returns the pointer to the ID resource. This method is exposed through ZoneMeta class
786 * for ICU internal implementation and useful for building hashtable using a time zone
787 * ID as a key.
788 * @param id zone id string
789 * @return the pointer of the ID resource, or NULL.
790 */
791 static const UChar* findID(const UnicodeString& id);
792
793 /**
794 * Resolve a link in Olson tzdata. When the given id is known and it's not a link,
795 * the id itself is returned. When the given id is known and it is a link, then
796 * dereferenced zone id is returned. When the given id is unknown, then it returns
797 * NULL.
798 * @param id zone id string
799 * @return the dereferenced zone or NULL
800 */
801 static const UChar* dereferOlsonLink(const UnicodeString& id);
802
803 /**
804 * Returns the region code associated with the given zone,
805 * or NULL if the zone is not known.
806 * @param id zone id string
807 * @return the region associated with the given zone
808 */
809 static const UChar* getRegion(const UnicodeString& id);
810
811 /**
812 * Returns the region code associated with the given zone,
813 * or NULL if the zone is not known.
814 * @param id zone id string
815 * @param status Status parameter
816 * @return the region associated with the given zone
817 */
818 static const UChar* getRegion(const UnicodeString& id, UErrorCode& status);
819
820 /**
821 * Parses the given custom time zone identifier
822 * @param id id A string of the form GMT[+-]hh:mm, GMT[+-]hhmm, or
823 * GMT[+-]hh.
824 * @param sign Receves parsed sign, 1 for positive, -1 for negative.
825 * @param hour Receives parsed hour field
826 * @param minute Receives parsed minute field
827 * @param second Receives parsed second field
828 * @return Returns TRUE when the given custom id is valid.
829 */
830 static UBool parseCustomID(const UnicodeString& id, int32_t& sign, int32_t& hour,
831 int32_t& minute, int32_t& second);
832
833 /**
834 * Parse a custom time zone identifier and return the normalized
835 * custom time zone identifier for the given custom id string.
836 * @param id a string of the form GMT[+-]hh:mm, GMT[+-]hhmm, or
837 * GMT[+-]hh.
838 * @param normalized Receives the normalized custom ID
839 * @param status Receives the status. When the input ID string is invalid,
840 * U_ILLEGAL_ARGUMENT_ERROR is set.
841 * @return The normalized custom id string.
842 */
843 static UnicodeString& getCustomID(const UnicodeString& id, UnicodeString& normalized,
844 UErrorCode& status);
845
846 /**
847 * Returns the normalized custome time zone ID for the given offset fields.
848 * @param hour offset hours
849 * @param min offset minutes
850 * @param sec offset seconds
851 * @param negative sign of the offset, TRUE for negative offset.
852 * @param id Receves the format result (normalized custom ID)
853 * @return The reference to id
854 */
855 static UnicodeString& formatCustomID(int32_t hour, int32_t min, int32_t sec,
856 UBool negative, UnicodeString& id);
857
858 /**
859 * Responsible for setting up DEFAULT_ZONE. Uses routines in TPlatformUtilities
860 * (i.e., platform-specific calls) to get the current system time zone. Failing
861 * that, uses the platform-specific default time zone. Failing that, uses GMT.
862 */
863 static void initDefault(void);
864
865 // See source file for documentation
866 /**
867 * Lookup the given name in our system zone table. If found,
868 * instantiate a new zone of that name and return it. If not
869 * found, return 0.
870 * @param name tthe given name of a system time zone.
871 * @return the TimeZone indicated by the 'name'.
872 */
873 static TimeZone* createSystemTimeZone(const UnicodeString& name);
874 static TimeZone* createSystemTimeZone(const UnicodeString& name, UErrorCode& ec);
875
876 UnicodeString fID; // this time zone's ID
877
878 friend class TZEnumeration;
879 };
880
881
882 // -------------------------------------
883
884 inline UnicodeString&
getID(UnicodeString & ID)885 TimeZone::getID(UnicodeString& ID) const
886 {
887 ID = fID;
888 return ID;
889 }
890
891 // -------------------------------------
892
893 inline void
setID(const UnicodeString & ID)894 TimeZone::setID(const UnicodeString& ID)
895 {
896 fID = ID;
897 }
898 U_NAMESPACE_END
899
900 #endif /* #if !UCONFIG_NO_FORMATTING */
901
902 #endif //_TIMEZONE
903 //eof
904