TimeZone represents a time zone offset, and also figures out daylight
* savings.
*
*
* Typically, you get a TimeZone using createDefault
* which creates a TimeZone based on the time zone where the program
* is running. For example, for a program running in Japan, createDefault
* creates a TimeZone object based on Japanese Standard Time.
*
*
* You can also get a TimeZone using createTimeZone along
* with a time zone ID. For instance, the time zone ID for the Pacific
* Standard Time zone is "PST". So, you can get a PST TimeZone object
* with:
*
*
* TimeZone *tz = TimeZone::createTimeZone("PST");
*
*
* You can use getAvailableIDs method to iterate through
* all the supported time zone IDs. You can then choose a
* supported ID to get a TimeZone.
* If the time zone you want is not represented by one of the
* supported IDs, then you can create a custom time zone ID with
* the following syntax:
*
* ** * For example, you might specify GMT+14:00 as a custom * time zone ID. The* GMT[+|-]hh[[:]mm] **
TimeZone that is returned
* when you specify a custom time zone ID does not include
* daylight savings time.
*
* TimeZone is an abstract class representing a time zone. A TimeZone is needed for
* Calendar to produce local time for a particular time zone. A TimeZone comprises
* three basic pieces of information:* The TimeZone class contains a static list containing a TimeZone object for every * combination of GMT offset and daylight-savings time rules currently in use in the * world, each with a unique ID. Each ID consists of a region (usually a continent or * ocean) and a city in that region, separated by a slash, (for example, Pacific * Standard Time is "America/Los_Angeles.") Because older versions of this class used * three- or four-letter abbreviations instead, there is also a table that maps the older * abbreviations to the newer ones (for example, "PST" maps to "America/LosAngeles"). * Anywhere the API requires an ID, you can use either form. *
* To create a new TimeZone, you call the factory function TimeZone::createTimeZone() * and pass it a time zone ID. You can use the createAvailableIDs() function to * obtain a list of all the time zone IDs recognized by createTimeZone(). *
* You can also use TimeZone::createDefault() to create a TimeZone. This function uses
* platform-specific APIs to produce a TimeZone for the time zone corresponding to
* the client's computer's physical location. For example, if you're in Japan (assuming
* your machine is set up correctly), TimeZone::createDefault() will return a TimeZone
* for Japanese Standard Time ("Asia/Tokyo").
*/
class U_I18N_API TimeZone {
public:
/**
* @stable
*/
virtual ~TimeZone();
/**
* The GMT zone has a raw offset of zero and does not use daylight
* savings time.
*/
static const TimeZone* GMT;
/**
* Creates a TimeZone for the given ID.
* @param ID the ID for a TimeZone, either an abbreviation such as
* "PST", a full name such as "America/Los_Angeles", or a custom ID
* such as "GMT-8:00".
* @return the specified TimeZone, or the GMT zone if the given ID
* cannot be understood. Return result guaranteed to be non-null. If you
* require that the specific zone asked for be returned, check the ID of the
* return result.
* @stable
*/
static TimeZone* createTimeZone(const UnicodeString& ID);
/**
* Returns a list of time zone IDs, one for each time zone with a given GMT offset.
* The return value is a list because there may be several times zones with the same
* GMT offset that differ in the way they handle daylight savings time. For example,
* the state of Arizona doesn't observe Daylight Savings time. So if you ask for
* the time zone IDs corresponding to GMT-7:00, you'll get back two time zone IDs:
* "America/Denver," which corresponds to Mountain Standard Time in the winter and
* Mountain Daylight Time in the summer, and "America/Phoenix", which corresponds to
* Mountain Standard Time year-round, even in the summer.
*
* The caller owns the list that is returned, but does not own the strings contained * in that list. Delete the array, but DON'T delete the elements in the array. * * @param rawOffset An offset from GMT in milliseconds. * @param numIDs Receives the number of items in the array that is returned. * @return An array of UnicodeString pointers, where each UnicodeString is * a time zone ID for a time zone with the given GMT offset. If * there is no timezone that matches the GMT offset * specified, NULL is returned. * @stable */ static const UnicodeString** const createAvailableIDs(int32_t rawOffset, int32_t& numIDs); /** * Returns a list of all time zone IDs supported by the TimeZone class (i.e., all * IDs that it's legal to pass to createTimeZone()). The caller owns the list that * is returned, but does not own the strings contained in that list. Delete the array, * but DON'T delete the elements in the array. * * @param numIDs Receives the number of zone IDs returned. * @return An array of UnicodeString pointers, where each is a time zone ID * supported by the TimeZone class. * @stable */ static const UnicodeString** const createAvailableIDs(int32_t& numIDs); /** * Creates a new copy of the default TimeZone for this host. Unless the default time * zone has already been set using adoptDefault() or setDefault(), the default is * determined by querying the system using methods in TPlatformUtilities. If the * system routines fail, or if they specify a TimeZone or TimeZone offset which is not * recognized, the TimeZone indicated by the ID kLastResortID is instantiated * and made the default. * * @return A default TimeZone. Clients are responsible for deleting the time zone * object returned. * @stable */ static TimeZone* createDefault(void); /** * Sets the default time zone (i.e., what's returned by getDefault()) to be the * specified time zone. If NULL is specified for the time zone, the default time * zone is set to the default host time zone. This call adopts the TimeZone object * passed in; the clent is no longer responsible for deleting it. * * @param zone A pointer to the new TimeZone object to use as the default. * @stable */ static void adoptDefault(TimeZone* zone); /** * Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted; * the caller remains responsible for deleting it. * * @param zone The given timezone. * @system */ static void setDefault(const TimeZone& zone); /** * Returns true if the two TimeZones are equal. (The TimeZone version only compares * IDs, but subclasses are expected to also compare the fields they add.) * * @param that The TimeZone object to be compared with. * @return True if the given TimeZone is equal to this TimeZone; false * otherwise. * @stable */ virtual UBool operator==(const TimeZone& that) const; /** * Returns true if the two TimeZones are NOT equal; that is, if operator==() returns * false. * * @param that The TimeZone object to be compared with. * @return True if the given TimeZone is not equal to this TimeZone; false * otherwise. * @stable */ UBool operator!=(const TimeZone& that) const {return !operator==(that);} /** * Returns the TimeZone's adjusted GMT offset (i.e., the number of milliseconds to add * to GMT to get local time in this time zone, taking daylight savings time into * account) as of a particular reference date. The reference date is used to determine * whether daylight savings time is in effect and needs to be figured into the offset * that is returned (in other words, what is the adjusted GMT offset in this time zone * at this particular date and time?). For the time zones produced by createTimeZone(), * the reference data is specified according to the Gregorian calendar, and the date * and time fields are in GMT, NOT local time. * * @param era The reference date's era * @param year The reference date's year * @param month The reference date's month (0-based; 0 is January) * @param day The reference date's day-in-month (1-based) * @param dayOfWeek The reference date's day-of-week (1-based; 1 is Sunday) * @param millis The reference date's milliseconds in day, UTT (NOT local time). * @return The offset in milliseconds to add to GMT to get local time. * @stable */ virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis, UErrorCode& status) const = 0; /** * @deprecated */ virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis) const = 0; /** * Gets the time zone offset, for current date, modified in case of * daylight savings. This is the offset to add *to* UTC to get local time. * @param era the era of the given date. * @param year the year in the given date. * @param month the month in the given date. * Month is 0-based. e.g., 0 for January. * @param day the day-in-month of the given date. * @param dayOfWeek the day-of-week of the given date. * @param milliseconds the millis in day in standard local time. * @param monthLength the length of the given month in days. * @return the offset to add *to* GMT to get local time. * @stable */ virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t milliseconds, int32_t monthLength, UErrorCode& status) const = 0; /** * Sets the TimeZone's raw GMT offset (i.e., the number of milliseconds to add * to GMT to get local time, before taking daylight savings time into account). * * @param offsetMillis The new raw GMT offset for this time zone. * @stable */ virtual void setRawOffset(int32_t offsetMillis) = 0; /** * Returns the TimeZone's raw GMT offset (i.e., the number of milliseconds to add * to GMT to get local time, before taking daylight savings time into account). * * @return The TimeZone's raw GMT offset. * @stable */ virtual int32_t getRawOffset(void) const = 0; /** * Fills in "ID" with the TimeZone's ID. * * @param ID Receives this TimeZone's ID. * @return "ID" * @stable */ UnicodeString& getID(UnicodeString& ID) const; /** * Sets the TimeZone's ID to the specified value. This doesn't affect any other * fields (for example, if you say< * blockquote>
* . TimeZone* foo = TimeZone::createTimeZone("America/New_York");
* . foo.setID("America/Los_Angeles");
*
* the time zone's GMT offset and daylight-savings rules don't change to those for
* Los Angeles. They're still those for New York. Only the ID has changed.)
*
* @param ID The new timezone ID.
* @stable
*/
void setID(const UnicodeString& ID);
/**
* Enum for use with getDisplayName
*/
enum EDisplayType {
SHORT = 1,
LONG
};
/**
* Returns a name of this time zone suitable for presentation to the user
* in the default locale.
* This method returns the long name, not including daylight savings.
* If the display name is not available for the locale,
* then this method returns a string in the format
* GMT[+-]hh:mm.
* @return the human-readable name of this time zone in the default locale.
* @stable
*/
UnicodeString& getDisplayName(UnicodeString& result) const;
/**
* Returns a name of this time zone suitable for presentation to the user
* in the specified locale.
* This method returns the long name, not including daylight savings.
* If the display name is not available for the locale,
* then this method returns a string in the format
* GMT[+-]hh:mm.
* @param locale the locale in which to supply the display name.
* @return the human-readable name of this time zone in the given locale
* or in the default locale if the given locale is not recognized.
* @stable
*/
UnicodeString& getDisplayName(const Locale& locale, UnicodeString& result) const;
/**
* Returns a name of this time zone suitable for presentation to the user
* in the default locale.
* If the display name is not available for the locale,
* then this method returns a string in the format
* GMT[+-]hh:mm.
* @param daylight if true, return the daylight savings name.
* @param style either LONG or SHORT
* @return the human-readable name of this time zone in the default locale.
* @stable
*/
UnicodeString& getDisplayName(UBool daylight, EDisplayType style, UnicodeString& result) const;
/**
* Returns a name of this time zone suitable for presentation to the user
* in the specified locale.
* If the display name is not available for the locale,
* then this method returns a string in the format
* GMT[+-]hh:mm.
* @param daylight if true, return the daylight savings name.
* @param style either LONG or SHORT
* @param locale the locale in which to supply the display name.
* @return the human-readable name of this time zone in the given locale
* or in the default locale if the given locale is not recognized.
* @stable
*/
UnicodeString& getDisplayName(UBool daylight, EDisplayType style, const Locale& locale, UnicodeString& result) const;
/**
* Queries if this time zone uses daylight savings time.
* @return true if this time zone uses daylight savings time,
* false, otherwise.
* @stable
*/
virtual UBool useDaylightTime(void) const = 0;
/**
* Queries if the given date is in daylight savings time in
* this time zone.
* @param date the given UDate.
* @return true if the given date is in daylight savings time,
* false, otherwise.
* @deprecated
*/
virtual UBool inDaylightTime(UDate date, UErrorCode& status) const = 0;
/**
* Returns true if this zone has the same rule and offset as another zone.
* That is, if this zone differs only in ID, if at all.
* @param other the TimeZone object to be compared with
* @return true if the given zone is the same as this one,
* with the possible exception of the ID
* @stable
*/
virtual UBool hasSameRules(const TimeZone& other) const;
/**
* Clones TimeZone objects polymorphically. Clients are responsible for deleting
* the TimeZone object cloned.
*
* @return A new copy of this TimeZone object.
* @stable
*/
virtual TimeZone* clone(void) const = 0;
/**
* Return the class ID for this class. This is useful only for
* comparing to a return value from getDynamicClassID(). For example:
*
* . Base* polymorphic_pointer = createPolymorphicObject();
* . if (polymorphic_pointer->getDynamicClassID() ==
* . Derived::getStaticClassID()) ...
*
* @return The class ID for all objects of this class.
* @stable
*/
static UClassID getStaticClassID(void) { return (UClassID)&fgClassID; }
/**
* Returns a unique class ID POLYMORPHICALLY. Pure virtual method. This method is to
* implement a simple version of RTTI, since not all C++ compilers support genuine
* RTTI. Polymorphic operator==() and clone() methods call this method.
* * Concrete subclasses of TimeZone must implement getDynamicClassID() and also a * static method and data member: *
* . static UClassID getStaticClassID() { return (UClassID)&fgClassID; }
* . static char fgClassID;
*
* @return The class ID for this object. All objects of a given class have the
* same class ID. Objects of other classes have different class IDs.
* @stable
*/
virtual UClassID getDynamicClassID(void) const = 0;
protected:
/**
* Default constructor. ID is initialized to the empty string.
* @stable
*/
TimeZone();
/**
* Copy constructor.
* @stable
*/
TimeZone(const TimeZone& source);
/**
* Default assignment operator.
* @stable
*/
TimeZone& operator=(const TimeZone& right);
private:
static char fgClassID;
static TimeZone* createCustomTimeZone(const UnicodeString&); // Creates a time zone based on the string.
static TimeZone* fgDefaultZone; // default time zone (lazy evaluated)
static const UnicodeString GMT_ID;
static const int32_t GMT_ID_LENGTH;
static const UnicodeString CUSTOM_ID;
////////////////////////////////////////////////////////////////
// Pointers into memory-mapped icudata. Writing to this memory
// will segfault! See tzdat.h for more details.
////////////////////////////////////////////////////////////////
/**
* DATA is the start of the memory-mapped zone data, and
* specifically points to the header object located there.
* May be zero if loading failed for some reason.
*/
static const TZHeader * DATA;
/**
* INDEX_BY_ID is an index table in lexicographic order of ID.
* Each entry is an offset from DATA to the zone object, which
* will either be a StandardZone or a DSTZone object.
*/
static const uint32_t* INDEX_BY_ID;
/**
* INDEX_BY_OFFSET is an OffsetIndex table. This table can only
* be walked through sequentially because the entries are of
* variable size.
*/
static const OffsetIndex* INDEX_BY_OFFSET;
////////////////////////////////////////////////////////////////
// Other system zone data structures
////////////////////////////////////////////////////////////////
/**
* ZONE_IDS is an array of all the system zone ID strings, in
* lexicographic order. The createAvailableIDs() methods return
* arrays of pointers into this array.
*/
static UnicodeString* ZONE_IDS;
/**
* If DATA_LOADED is true, then an attempt has already been made
* to load the system zone data, and further attempts will not be
* made. If DATA_LOADED is true, DATA itself will be zero if
* loading failed, or non-zero if it succeeded.
*/
static UBool DATA_LOADED;
/**
* The mutex object used to control write access to DATA,
* INDEX_BY_ID, INDEX_BY_OFFSET, and ZONE_IDS. Also used to
* control read/write access to fgDefaultZone.
*/
static UMTX LOCK;
/**
* Responsible for setting up fgDefaultZone. Uses routines in TPlatformUtilities
* (i.e., platform-specific calls) to get the current system time zone. Failing
* that, uses the platform-specific default time zone. Failing that, uses GMT.
*/
static void initDefault(void);
// See source file for documentation
static void loadZoneData(void);
// See source file for documentation
static UBool U_CALLCONV isDataAcceptable(void *context,
const char *type, const char *name,
const UDataInfo *pInfo);
// See source file for documentation
static TimeZone* createSystemTimeZone(const UnicodeString& name);
UnicodeString fID; // this time zone's ID
};
// -------------------------------------
inline UnicodeString&
TimeZone::getID(UnicodeString& ID) const
{
ID = fID;
return ID;
}
// -------------------------------------
inline void
TimeZone::setID(const UnicodeString& ID)
{
fID = ID;
}
#endif //_TIMEZONE
//eof