1 /************************************************************************* 2 * Copyright (c) 1997-2013, 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 /** 137 * Returns the "unknown" time zone. 138 * It behaves like the GMT/UTC time zone but has the 139 * <code>UCAL_UNKNOWN_ZONE_ID</code> = "Etc/Unknown". 140 * createTimeZone() returns a mutable clone of this time zone if the input ID is not recognized. 141 * 142 * @return the "unknown" time zone. 143 * @see UCAL_UNKNOWN_ZONE_ID 144 * @see createTimeZone 145 * @see getGMT 146 * @stable ICU 49 147 */ 148 static const TimeZone& U_EXPORT2 getUnknown(); 149 150 /** 151 * The GMT (=UTC) time zone has a raw offset of zero and does not use daylight 152 * savings time. This is a commonly used time zone. 153 * 154 * <p>Note: For backward compatibility reason, the ID used by the time 155 * zone returned by this method is "GMT", although the ICU's canonical 156 * ID for the GMT time zone is "Etc/GMT". 157 * 158 * @return the GMT/UTC time zone. 159 * @see getUnknown 160 * @stable ICU 2.0 161 */ 162 static const TimeZone* U_EXPORT2 getGMT(void); 163 164 /** 165 * Creates a <code>TimeZone</code> for the given ID. 166 * @param ID the ID for a <code>TimeZone</code>, such as "America/Los_Angeles", 167 * or a custom ID such as "GMT-8:00". 168 * @return the specified <code>TimeZone</code>, or a mutable clone of getUnknown() 169 * if the given ID cannot be understood or if the given ID is "Etc/Unknown". 170 * The return result is guaranteed to be non-NULL. 171 * If you require that the specific zone asked for be returned, 172 * compare the result with getUnknown() or check the ID of the return result. 173 * @stable ICU 2.0 174 */ 175 static TimeZone* U_EXPORT2 createTimeZone(const UnicodeString& ID); 176 177 /** 178 * Returns an enumeration over system time zone IDs with the given 179 * filter conditions. 180 * @param zoneType The system time zone type. 181 * @param region The ISO 3166 two-letter country code or UN M.49 182 * three-digit area code. When NULL, no filtering 183 * done by region. 184 * @param rawOffset An offset from GMT in milliseconds, ignoring 185 * the effect of daylight savings time, if any. 186 * When NULL, no filtering done by zone offset. 187 * @param ec Output param to filled in with a success or 188 * an error. 189 * @return an enumeration object, owned by the caller. 190 * @stable ICU 4.8 191 */ 192 static StringEnumeration* U_EXPORT2 createTimeZoneIDEnumeration( 193 USystemTimeZoneType zoneType, 194 const char* region, 195 const int32_t* rawOffset, 196 UErrorCode& ec); 197 198 /** 199 * Returns an enumeration over all recognized time zone IDs. (i.e., 200 * all strings that createTimeZone() accepts) 201 * 202 * @return an enumeration object, owned by the caller. 203 * @stable ICU 2.4 204 */ 205 static StringEnumeration* U_EXPORT2 createEnumeration(); 206 207 /** 208 * Returns an enumeration over time zone IDs with a given raw 209 * offset from GMT. There may be several times zones with the 210 * same GMT offset that differ in the way they handle daylight 211 * savings time. For example, the state of Arizona doesn't 212 * observe daylight savings time. If you ask for the time zone 213 * IDs corresponding to GMT-7:00, you'll get back an enumeration 214 * over two time zone IDs: "America/Denver," which corresponds to 215 * Mountain Standard Time in the winter and Mountain Daylight Time 216 * in the summer, and "America/Phoenix", which corresponds to 217 * Mountain Standard Time year-round, even in the summer. 218 * 219 * @param rawOffset an offset from GMT in milliseconds, ignoring 220 * the effect of daylight savings time, if any 221 * @return an enumeration object, owned by the caller 222 * @stable ICU 2.4 223 */ 224 static StringEnumeration* U_EXPORT2 createEnumeration(int32_t rawOffset); 225 226 /** 227 * Returns an enumeration over time zone IDs associated with the 228 * given country. Some zones are affiliated with no country 229 * (e.g., "UTC"); these may also be retrieved, as a group. 230 * 231 * @param country The ISO 3166 two-letter country code, or NULL to 232 * retrieve zones not affiliated with any country. 233 * @return an enumeration object, owned by the caller 234 * @stable ICU 2.4 235 */ 236 static StringEnumeration* U_EXPORT2 createEnumeration(const char* country); 237 238 /** 239 * Returns the number of IDs in the equivalency group that 240 * includes the given ID. An equivalency group contains zones 241 * that have the same GMT offset and rules. 242 * 243 * <p>The returned count includes the given ID; it is always >= 1. 244 * The given ID must be a system time zone. If it is not, returns 245 * zero. 246 * @param id a system time zone ID 247 * @return the number of zones in the equivalency group containing 248 * 'id', or zero if 'id' is not a valid system ID 249 * @see #getEquivalentID 250 * @stable ICU 2.0 251 */ 252 static int32_t U_EXPORT2 countEquivalentIDs(const UnicodeString& id); 253 254 /** 255 * Returns an ID in the equivalency group that 256 * includes the given ID. An equivalency group contains zones 257 * that have the same GMT offset and rules. 258 * 259 * <p>The given index must be in the range 0..n-1, where n is the 260 * value returned by <code>countEquivalentIDs(id)</code>. For 261 * some value of 'index', the returned value will be equal to the 262 * given id. If the given id is not a valid system time zone, or 263 * if 'index' is out of range, then returns an empty string. 264 * @param id a system time zone ID 265 * @param index a value from 0 to n-1, where n is the value 266 * returned by <code>countEquivalentIDs(id)</code> 267 * @return the ID of the index-th zone in the equivalency group 268 * containing 'id', or an empty string if 'id' is not a valid 269 * system ID or 'index' is out of range 270 * @see #countEquivalentIDs 271 * @stable ICU 2.0 272 */ 273 static const UnicodeString U_EXPORT2 getEquivalentID(const UnicodeString& id, 274 int32_t index); 275 276 /** 277 * Creates a new copy of the default TimeZone for this host. Unless the default time 278 * zone has already been set using adoptDefault() or setDefault(), the default is 279 * determined by querying the system using methods in TPlatformUtilities. If the 280 * system routines fail, or if they specify a TimeZone or TimeZone offset which is not 281 * recognized, the TimeZone indicated by the ID kLastResortID is instantiated 282 * and made the default. 283 * 284 * @return A default TimeZone. Clients are responsible for deleting the time zone 285 * object returned. 286 * @stable ICU 2.0 287 */ 288 static TimeZone* U_EXPORT2 createDefault(void); 289 290 /** 291 * Sets the default time zone (i.e., what's returned by createDefault()) to be the 292 * specified time zone. If NULL is specified for the time zone, the default time 293 * zone is set to the default host time zone. This call adopts the TimeZone object 294 * passed in; the clent is no longer responsible for deleting it. 295 * 296 * @param zone A pointer to the new TimeZone object to use as the default. 297 * @stable ICU 2.0 298 */ 299 static void U_EXPORT2 adoptDefault(TimeZone* zone); 300 301 #ifndef U_HIDE_SYSTEM_API 302 /** 303 * Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted; 304 * the caller remains responsible for deleting it. 305 * 306 * @param zone The given timezone. 307 * @system 308 * @stable ICU 2.0 309 */ 310 static void U_EXPORT2 setDefault(const TimeZone& zone); 311 #endif /* U_HIDE_SYSTEM_API */ 312 313 /** 314 * Returns the timezone data version currently used by ICU. 315 * @param status Output param to filled in with a success or an error. 316 * @return the version string, such as "2007f" 317 * @stable ICU 3.8 318 */ 319 static const char* U_EXPORT2 getTZDataVersion(UErrorCode& status); 320 321 /** 322 * Returns the canonical system timezone ID or the normalized 323 * custom time zone ID for the given time zone ID. 324 * @param id The input time zone ID to be canonicalized. 325 * @param canonicalID Receives the canonical system time zone ID 326 * or the custom time zone ID in normalized format. 327 * @param status Recevies the status. When the given time zone ID 328 * is neither a known system time zone ID nor a 329 * valid custom time zone ID, U_ILLEGAL_ARGUMENT_ERROR 330 * is set. 331 * @return A reference to the result. 332 * @stable ICU 4.0 333 */ 334 static UnicodeString& U_EXPORT2 getCanonicalID(const UnicodeString& id, 335 UnicodeString& canonicalID, UErrorCode& status); 336 337 /** 338 * Returns the canonical system time zone ID or the normalized 339 * custom time zone ID for the given time zone ID. 340 * @param id The input time zone ID to be canonicalized. 341 * @param canonicalID Receives the canonical system time zone ID 342 * or the custom time zone ID in normalized format. 343 * @param isSystemID Receives if the given ID is a known system 344 * time zone ID. 345 * @param status Recevies the status. When the given time zone ID 346 * is neither a known system time zone ID nor a 347 * valid custom time zone ID, U_ILLEGAL_ARGUMENT_ERROR 348 * is set. 349 * @return A reference to the result. 350 * @stable ICU 4.0 351 */ 352 static UnicodeString& U_EXPORT2 getCanonicalID(const UnicodeString& id, 353 UnicodeString& canonicalID, UBool& isSystemID, UErrorCode& status); 354 355 /** 356 * Returns true if the two TimeZones are equal. (The TimeZone version only compares 357 * IDs, but subclasses are expected to also compare the fields they add.) 358 * 359 * @param that The TimeZone object to be compared with. 360 * @return True if the given TimeZone is equal to this TimeZone; false 361 * otherwise. 362 * @stable ICU 2.0 363 */ 364 virtual UBool operator==(const TimeZone& that) const; 365 366 /** 367 * Returns true if the two TimeZones are NOT equal; that is, if operator==() returns 368 * false. 369 * 370 * @param that The TimeZone object to be compared with. 371 * @return True if the given TimeZone is not equal to this TimeZone; false 372 * otherwise. 373 * @stable ICU 2.0 374 */ 375 UBool operator!=(const TimeZone& that) const {return !operator==(that);} 376 377 /** 378 * Returns the TimeZone's adjusted GMT offset (i.e., the number of milliseconds to add 379 * to GMT to get local time in this time zone, taking daylight savings time into 380 * account) as of a particular reference date. The reference date is used to determine 381 * whether daylight savings time is in effect and needs to be figured into the offset 382 * that is returned (in other words, what is the adjusted GMT offset in this time zone 383 * at this particular date and time?). For the time zones produced by createTimeZone(), 384 * the reference data is specified according to the Gregorian calendar, and the date 385 * and time fields are local standard time. 386 * 387 * <p>Note: Don't call this method. Instead, call the getOffset(UDate...) overload, 388 * which returns both the raw and the DST offset for a given time. This method 389 * is retained only for backward compatibility. 390 * 391 * @param era The reference date's era 392 * @param year The reference date's year 393 * @param month The reference date's month (0-based; 0 is January) 394 * @param day The reference date's day-in-month (1-based) 395 * @param dayOfWeek The reference date's day-of-week (1-based; 1 is Sunday) 396 * @param millis The reference date's milliseconds in day, local standard time 397 * @param status Output param to filled in with a success or an error. 398 * @return The offset in milliseconds to add to GMT to get local time. 399 * @stable ICU 2.0 400 */ 401 virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day, 402 uint8_t dayOfWeek, int32_t millis, UErrorCode& status) const = 0; 403 404 /** 405 * Gets the time zone offset, for current date, modified in case of 406 * daylight savings. This is the offset to add *to* UTC to get local time. 407 * 408 * <p>Note: Don't call this method. Instead, call the getOffset(UDate...) overload, 409 * which returns both the raw and the DST offset for a given time. This method 410 * is retained only for backward compatibility. 411 * 412 * @param era the era of the given date. 413 * @param year the year in the given date. 414 * @param month the month in the given date. 415 * Month is 0-based. e.g., 0 for January. 416 * @param day the day-in-month of the given date. 417 * @param dayOfWeek the day-of-week of the given date. 418 * @param milliseconds the millis in day in <em>standard</em> local time. 419 * @param monthLength the length of the given month in days. 420 * @param status Output param to filled in with a success or an error. 421 * @return the offset to add *to* GMT to get local time. 422 * @stable ICU 2.0 423 */ 424 virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day, 425 uint8_t dayOfWeek, int32_t milliseconds, 426 int32_t monthLength, UErrorCode& status) const = 0; 427 428 /** 429 * Returns the time zone raw and GMT offset for the given moment 430 * in time. Upon return, local-millis = GMT-millis + rawOffset + 431 * dstOffset. All computations are performed in the proleptic 432 * Gregorian calendar. The default implementation in the TimeZone 433 * class delegates to the 8-argument getOffset(). 434 * 435 * @param date moment in time for which to return offsets, in 436 * units of milliseconds from January 1, 1970 0:00 GMT, either GMT 437 * time or local wall time, depending on `local'. 438 * @param local if true, `date' is local wall time; otherwise it 439 * is in GMT time. 440 * @param rawOffset output parameter to receive the raw offset, that 441 * is, the offset not including DST adjustments 442 * @param dstOffset output parameter to receive the DST offset, 443 * that is, the offset to be added to `rawOffset' to obtain the 444 * total offset between local and GMT time. If DST is not in 445 * effect, this value is zero; otherwise it is a positive value, 446 * typically one hour. 447 * @param ec input-output error code 448 * 449 * @stable ICU 2.8 450 */ 451 virtual void getOffset(UDate date, UBool local, int32_t& rawOffset, 452 int32_t& dstOffset, UErrorCode& ec) const; 453 454 /** 455 * Sets the TimeZone's raw GMT offset (i.e., the number of milliseconds to add 456 * to GMT to get local time, before taking daylight savings time into account). 457 * 458 * @param offsetMillis The new raw GMT offset for this time zone. 459 * @stable ICU 2.0 460 */ 461 virtual void setRawOffset(int32_t offsetMillis) = 0; 462 463 /** 464 * Returns the TimeZone's raw GMT offset (i.e., the number of milliseconds to add 465 * to GMT to get local time, before taking daylight savings time into account). 466 * 467 * @return The TimeZone's raw GMT offset. 468 * @stable ICU 2.0 469 */ 470 virtual int32_t getRawOffset(void) const = 0; 471 472 /** 473 * Fills in "ID" with the TimeZone's ID. 474 * 475 * @param ID Receives this TimeZone's ID. 476 * @return A reference to 'ID' 477 * @stable ICU 2.0 478 */ 479 UnicodeString& getID(UnicodeString& ID) const; 480 481 /** 482 * Sets the TimeZone's ID to the specified value. This doesn't affect any other 483 * fields (for example, if you say< 484 * blockquote><pre> 485 * . TimeZone* foo = TimeZone::createTimeZone("America/New_York"); 486 * . foo.setID("America/Los_Angeles"); 487 * </pre>\htmlonly</blockquote>\endhtmlonly 488 * the time zone's GMT offset and daylight-savings rules don't change to those for 489 * Los Angeles. They're still those for New York. Only the ID has changed.) 490 * 491 * @param ID The new time zone ID. 492 * @stable ICU 2.0 493 */ 494 void setID(const UnicodeString& ID); 495 496 /** 497 * Enum for use with getDisplayName 498 * @stable ICU 2.4 499 */ 500 enum EDisplayType { 501 /** 502 * Selector for short display name 503 * @stable ICU 2.4 504 */ 505 SHORT = 1, 506 /** 507 * Selector for long display name 508 * @stable ICU 2.4 509 */ 510 LONG, 511 /** 512 * Selector for short generic display name 513 * @stable ICU 4.4 514 */ 515 SHORT_GENERIC, 516 /** 517 * Selector for long generic display name 518 * @stable ICU 4.4 519 */ 520 LONG_GENERIC, 521 /** 522 * Selector for short display name derived 523 * from time zone offset 524 * @stable ICU 4.4 525 */ 526 SHORT_GMT, 527 /** 528 * Selector for long display name derived 529 * from time zone offset 530 * @stable ICU 4.4 531 */ 532 LONG_GMT, 533 /** 534 * Selector for short display name derived 535 * from the time zone's fallback name 536 * @stable ICU 4.4 537 */ 538 SHORT_COMMONLY_USED, 539 /** 540 * Selector for long display name derived 541 * from the time zone's fallback name 542 * @stable ICU 4.4 543 */ 544 GENERIC_LOCATION 545 }; 546 547 /** 548 * Returns a name of this time zone suitable for presentation to the user 549 * in the default locale. 550 * This method returns the long name, not including daylight savings. 551 * If the display name is not available for the locale, 552 * then this method returns a string in the format 553 * <code>GMT[+-]hh:mm</code>. 554 * @param result the human-readable name of this time zone in the default locale. 555 * @return A reference to 'result'. 556 * @stable ICU 2.0 557 */ 558 UnicodeString& getDisplayName(UnicodeString& result) const; 559 560 /** 561 * Returns a name of this time zone suitable for presentation to the user 562 * in the specified locale. 563 * This method returns the long name, not including daylight savings. 564 * If the display name is not available for the locale, 565 * then this method returns a string in the format 566 * <code>GMT[+-]hh:mm</code>. 567 * @param locale the locale in which to supply the display name. 568 * @param result the human-readable name of this time zone in the given locale 569 * or in the default locale if the given locale is not recognized. 570 * @return A reference to 'result'. 571 * @stable ICU 2.0 572 */ 573 UnicodeString& getDisplayName(const Locale& locale, UnicodeString& result) const; 574 575 /** 576 * Returns a name of this time zone suitable for presentation to the user 577 * in the default locale. 578 * If the display name is not available for the locale, 579 * then this method returns a string in the format 580 * <code>GMT[+-]hh:mm</code>. 581 * @param daylight if true, return the daylight savings name. 582 * @param style 583 * @param result the human-readable name of this time zone in the default locale. 584 * @return A reference to 'result'. 585 * @stable ICU 2.0 586 */ 587 UnicodeString& getDisplayName(UBool daylight, EDisplayType style, UnicodeString& result) const; 588 589 /** 590 * Returns a name of this time zone suitable for presentation to the user 591 * in the specified locale. 592 * If the display name is not available for the locale, 593 * then this method returns a string in the format 594 * <code>GMT[+-]hh:mm</code>. 595 * @param daylight if true, return the daylight savings name. 596 * @param style 597 * @param locale the locale in which to supply the display name. 598 * @param result the human-readable name of this time zone in the given locale 599 * or in the default locale if the given locale is not recognized. 600 * @return A refence to 'result'. 601 * @stable ICU 2.0 602 */ 603 UnicodeString& getDisplayName(UBool daylight, EDisplayType style, const Locale& locale, UnicodeString& result) const; 604 605 /** 606 * Queries if this time zone uses daylight savings time. 607 * @return true if this time zone uses daylight savings time, 608 * false, otherwise. 609 * <p><strong>Note:</strong>The default implementation of 610 * ICU TimeZone uses the tz database, which supports historic 611 * rule changes, for system time zones. With the implementation, 612 * there are time zones that used daylight savings time in the 613 * past, but no longer used currently. For example, Asia/Tokyo has 614 * never used daylight savings time since 1951. Most clients would 615 * expect that this method to return <code>FALSE</code> for such case. 616 * The default implementation of this method returns <code>TRUE</code> 617 * when the time zone uses daylight savings time in the current 618 * (Gregorian) calendar year. 619 * <p>In Java 7, <code>observesDaylightTime()</code> was added in 620 * addition to <code>useDaylightTime()</code>. In Java, <code>useDaylightTime()</code> 621 * only checks if daylight saving time is observed by the last known 622 * rule. This specification might not be what most users would expect 623 * if daylight saving time is currently observed, but not scheduled 624 * in future. In this case, Java's <code>userDaylightTime()</code> returns 625 * <code>false</code>. To resolve the issue, Java 7 added <code>observesDaylightTime()</code>, 626 * which takes the current rule into account. The method <code>observesDaylightTime()</code> 627 * was added in ICU4J for supporting API signature compatibility with JDK. 628 * In general, ICU4C also provides JDK compatible methods, but the current 629 * implementation <code>userDaylightTime()</code> serves the purpose 630 * (takes the current rule into account), <code>observesDaylightTime()</code> 631 * is not added in ICU4C. In addition to <code>useDaylightTime()</code>, ICU4C 632 * <code>BasicTimeZone</code> class (Note that <code>TimeZone::createTimeZone(const UnicodeString &ID)</code> 633 * always returns a <code>BasicTimeZone</code>) provides a series of methods allowing 634 * historic and future time zone rule iteration, so you can check if daylight saving 635 * time is observed or not within a given period. 636 * 637 * @stable ICU 2.0 638 */ 639 virtual UBool useDaylightTime(void) const = 0; 640 641 /** 642 * Queries if the given date is in daylight savings time in 643 * this time zone. 644 * This method is wasteful since it creates a new GregorianCalendar and 645 * deletes it each time it is called. This is a deprecated method 646 * and provided only for Java compatibility. 647 * 648 * @param date the given UDate. 649 * @param status Output param filled in with success/error code. 650 * @return true if the given date is in daylight savings time, 651 * false, otherwise. 652 * @deprecated ICU 2.4. Use Calendar::inDaylightTime() instead. 653 */ 654 virtual UBool inDaylightTime(UDate date, UErrorCode& status) const = 0; 655 656 /** 657 * Returns true if this zone has the same rule and offset as another zone. 658 * That is, if this zone differs only in ID, if at all. 659 * @param other the <code>TimeZone</code> object to be compared with 660 * @return true if the given zone is the same as this one, 661 * with the possible exception of the ID 662 * @stable ICU 2.0 663 */ 664 virtual UBool hasSameRules(const TimeZone& other) const; 665 666 /** 667 * Clones TimeZone objects polymorphically. Clients are responsible for deleting 668 * the TimeZone object cloned. 669 * 670 * @return A new copy of this TimeZone object. 671 * @stable ICU 2.0 672 */ 673 virtual TimeZone* clone(void) const = 0; 674 675 /** 676 * Return the class ID for this class. This is useful only for 677 * comparing to a return value from getDynamicClassID(). 678 * @return The class ID for all objects of this class. 679 * @stable ICU 2.0 680 */ 681 static UClassID U_EXPORT2 getStaticClassID(void); 682 683 /** 684 * Returns a unique class ID POLYMORPHICALLY. This method is to 685 * implement a simple version of RTTI, since not all C++ compilers support genuine 686 * RTTI. Polymorphic operator==() and clone() methods call this method. 687 * <P> 688 * Concrete subclasses of TimeZone must use the UOBJECT_DEFINE_RTTI_IMPLEMENTATION 689 * macro from uobject.h in their implementation to provide correct RTTI information. 690 * @return The class ID for this object. All objects of a given class have the 691 * same class ID. Objects of other classes have different class IDs. 692 * @stable ICU 2.0 693 */ 694 virtual UClassID getDynamicClassID(void) const = 0; 695 696 /** 697 * Returns the amount of time to be added to local standard time 698 * to get local wall clock time. 699 * <p> 700 * The default implementation always returns 3600000 milliseconds 701 * (i.e., one hour) if this time zone observes Daylight Saving 702 * Time. Otherwise, 0 (zero) is returned. 703 * <p> 704 * If an underlying TimeZone implementation subclass supports 705 * historical Daylight Saving Time changes, this method returns 706 * the known latest daylight saving value. 707 * 708 * @return the amount of saving time in milliseconds 709 * @stable ICU 3.6 710 */ 711 virtual int32_t getDSTSavings() const; 712 713 /** 714 * Gets the region code associated with the given 715 * system time zone ID. The region code is either ISO 3166 716 * 2-letter country code or UN M.49 3-digit area code. 717 * When the time zone is not associated with a specific location, 718 * for example - "Etc/UTC", "EST5EDT", then this method returns 719 * "001" (UN M.49 area code for World). 720 * 721 * @param id The system time zone ID. 722 * @param region Output buffer for receiving the region code. 723 * @param capacity The size of the output buffer. 724 * @param status Receives the status. When the given time zone ID 725 * is not a known system time zone ID, 726 * U_ILLEGAL_ARGUMENT_ERROR is set. 727 * @return The length of the output region code. 728 * @stable ICU 4.8 729 */ 730 static int32_t U_EXPORT2 getRegion(const UnicodeString& id, 731 char *region, int32_t capacity, UErrorCode& status); 732 733 protected: 734 735 /** 736 * Default constructor. ID is initialized to the empty string. 737 * @stable ICU 2.0 738 */ 739 TimeZone(); 740 741 /** 742 * Construct a TimeZone with a given ID. 743 * @param id a system time zone ID 744 * @stable ICU 2.0 745 */ 746 TimeZone(const UnicodeString &id); 747 748 /** 749 * Copy constructor. 750 * @param source the object to be copied. 751 * @stable ICU 2.0 752 */ 753 TimeZone(const TimeZone& source); 754 755 /** 756 * Default assignment operator. 757 * @param right the object to be copied. 758 * @stable ICU 2.0 759 */ 760 TimeZone& operator=(const TimeZone& right); 761 762 #ifndef U_HIDE_INTERNAL_API 763 /** 764 * Utility function. For internally loading rule data. 765 * @param top Top resource bundle for tz data 766 * @param ruleid ID of rule to load 767 * @param oldbundle Old bundle to reuse or NULL 768 * @param status Status parameter 769 * @return either a new bundle or *oldbundle 770 * @internal 771 */ 772 static UResourceBundle* loadRule(const UResourceBundle* top, const UnicodeString& ruleid, UResourceBundle* oldbundle, UErrorCode&status); 773 #endif /* U_HIDE_INTERNAL_API */ 774 775 private: 776 friend class ZoneMeta; 777 778 779 static TimeZone* createCustomTimeZone(const UnicodeString&); // Creates a time zone based on the string. 780 781 /** 782 * Finds the given ID in the Olson tzdata. If the given ID is found in the tzdata, 783 * returns the pointer to the ID resource. This method is exposed through ZoneMeta class 784 * for ICU internal implementation and useful for building hashtable using a time zone 785 * ID as a key. 786 * @param id zone id string 787 * @return the pointer of the ID resource, or NULL. 788 */ 789 static const UChar* findID(const UnicodeString& id); 790 791 /** 792 * Resolve a link in Olson tzdata. When the given id is known and it's not a link, 793 * the id itself is returned. When the given id is known and it is a link, then 794 * dereferenced zone id is returned. When the given id is unknown, then it returns 795 * NULL. 796 * @param id zone id string 797 * @return the dereferenced zone or NULL 798 */ 799 static const UChar* dereferOlsonLink(const UnicodeString& id); 800 801 /** 802 * Returns the region code associated with the given zone, 803 * or NULL if the zone is not known. 804 * @param id zone id string 805 * @return the region associated with the given zone 806 */ 807 static const UChar* getRegion(const UnicodeString& id); 808 809 /** 810 * Returns the region code associated with the given zone, 811 * or NULL if the zone is not known. 812 * @param id zone id string 813 * @param status Status parameter 814 * @return the region associated with the given zone 815 */ 816 static const UChar* getRegion(const UnicodeString& id, UErrorCode& status); 817 818 /** 819 * Parses the given custom time zone identifier 820 * @param id id A string of the form GMT[+-]hh:mm, GMT[+-]hhmm, or 821 * GMT[+-]hh. 822 * @param sign Receves parsed sign, 1 for positive, -1 for negative. 823 * @param hour Receives parsed hour field 824 * @param minute Receives parsed minute field 825 * @param second Receives parsed second field 826 * @return Returns TRUE when the given custom id is valid. 827 */ 828 static UBool parseCustomID(const UnicodeString& id, int32_t& sign, int32_t& hour, 829 int32_t& minute, int32_t& second); 830 831 /** 832 * Parse a custom time zone identifier and return the normalized 833 * custom time zone identifier for the given custom id string. 834 * @param id a string of the form GMT[+-]hh:mm, GMT[+-]hhmm, or 835 * GMT[+-]hh. 836 * @param normalized Receives the normalized custom ID 837 * @param status Receives the status. When the input ID string is invalid, 838 * U_ILLEGAL_ARGUMENT_ERROR is set. 839 * @return The normalized custom id string. 840 */ 841 static UnicodeString& getCustomID(const UnicodeString& id, UnicodeString& normalized, 842 UErrorCode& status); 843 844 /** 845 * Returns the normalized custome time zone ID for the given offset fields. 846 * @param hour offset hours 847 * @param min offset minutes 848 * @param sec offset seconds 849 * @param negative sign of the offset, TRUE for negative offset. 850 * @param id Receves the format result (normalized custom ID) 851 * @return The reference to id 852 */ 853 static UnicodeString& formatCustomID(int32_t hour, int32_t min, int32_t sec, 854 UBool negative, UnicodeString& id); 855 856 /** 857 * Responsible for setting up DEFAULT_ZONE. Uses routines in TPlatformUtilities 858 * (i.e., platform-specific calls) to get the current system time zone. Failing 859 * that, uses the platform-specific default time zone. Failing that, uses GMT. 860 */ 861 static void initDefault(void); 862 863 // See source file for documentation 864 /** 865 * Lookup the given name in our system zone table. If found, 866 * instantiate a new zone of that name and return it. If not 867 * found, return 0. 868 * @param name tthe given name of a system time zone. 869 * @return the TimeZone indicated by the 'name'. 870 */ 871 static TimeZone* createSystemTimeZone(const UnicodeString& name); 872 static TimeZone* createSystemTimeZone(const UnicodeString& name, UErrorCode& ec); 873 874 UnicodeString fID; // this time zone's ID 875 876 friend class TZEnumeration; 877 }; 878 879 880 // ------------------------------------- 881 882 inline UnicodeString& 883 TimeZone::getID(UnicodeString& ID) const 884 { 885 ID = fID; 886 return ID; 887 } 888 889 // ------------------------------------- 890 891 inline void 892 TimeZone::setID(const UnicodeString& ID) 893 { 894 fID = ID; 895 } 896 U_NAMESPACE_END 897 898 #endif /* #if !UCONFIG_NO_FORMATTING */ 899 900 #endif //_TIMEZONE 901 //eof 902
