305 lines
9.9 KiB
C++
305 lines
9.9 KiB
C++
/*
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**********************************************************************
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* Copyright (c) 2003-2005, International Business Machines
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* Corporation and others. All Rights Reserved.
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**********************************************************************
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* Author: Alan Liu
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* Created: July 21 2003
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* Since: ICU 2.8
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**********************************************************************
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*/
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#ifndef OLSONTZ_H
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#define OLSONTZ_H
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_FORMATTING
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#include "unicode/timezone.h"
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struct UResourceBundle;
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U_NAMESPACE_BEGIN
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class SimpleTimeZone;
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/**
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* A time zone based on the Olson database. Olson time zones change
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* behavior over time. The raw offset, rules, presence or absence of
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* daylight savings time, and even the daylight savings amount can all
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* vary.
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*
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* This class uses a resource bundle named "zoneinfo". Zoneinfo is a
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* table containing different kinds of resources. In several places,
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* zones are referred to using integers. A zone's integer is a number
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* from 0..n-1, where n is the number of zones, with the zones sorted
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* in lexicographic order.
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*
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* 1. Zones. These have keys corresponding to the Olson IDs, e.g.,
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* "Asia/Shanghai". Each resource describes the behavior of the given
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* zone. Zones come in several formats, which are differentiated
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* based on length.
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*
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* a. Alias (int, length 1). An alias zone is an int resource. The
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* integer is the zone number of the target zone. The key of this
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* resource is an alternate name for the target zone. Aliases
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* represent Olson links and ICU compatibility IDs.
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*
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* b. Simple zone (array, length 3). The three subelements are:
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*
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* i. An intvector of transitions. These are given in epoch
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* seconds. This may be an empty invector (length 0). If the
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* transtions list is empty, then the zone's behavior is fixed and
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* given by the offset list, which will contain exactly one pair.
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* Otherwise each transtion indicates a time after which (inclusive)
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* the associated offset pair is in effect.
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*
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* ii. An intvector of offsets. These are in pairs of raw offset /
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* DST offset, in units of seconds. There will be at least one pair
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* (length >= 2 && length % 2 == 0).
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*
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* iii. A binary resource. This is of the same length as the
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* transitions vector, so length may be zero. Each unsigned byte
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* corresponds to one transition, and has a value of 0..n-1, where n
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* is the number of pairs in the offset vector. This forms a map
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* between transitions and offset pairs.
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*
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* c. Simple zone with aliases (array, length 4). This is like a
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* simple zone, but also contains a fourth element:
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*
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* iv. An intvector of aliases. This list includes this zone
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* itself, and lists all aliases of this zone.
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*
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* d. Complex zone (array, length 5). This is like a simple zone,
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* but contains two more elements:
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*
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* iv. A string, giving the name of a rule. This is the "final
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* rule", which governs the zone's behavior beginning in the "final
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* year". The rule ID is given without leading underscore, e.g.,
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* "EU".
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*
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* v. An intvector of length 2, containing the raw offset for the
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* final rule (in seconds), and the final year. The final rule
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* takes effect for years >= the final year.
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*
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* e. Complex zone with aliases (array, length 6). This is like a
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* complex zone, but also contains a sixth element:
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*
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* vi. An intvector of aliases. This list includes this zone
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* itself, and lists all aliases of this zone.
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*
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* 2. Rules. These have keys corresponding to the Olson rule IDs,
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* with an underscore prepended, e.g., "_EU". Each resource describes
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* the behavior of the given rule using an intvector, containing the
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* onset list, the cessation list, and the DST savings. The onset and
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* cessation lists consist of the month, dowim, dow, time, and time
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* mode. The end result is that the 11 integers describing the rule
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* can be passed directly into the SimpleTimeZone 13-argument
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* constructor (the other two arguments will be the raw offset, taken
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* from the complex zone element 5, and the ID string, which is not
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* used), with the times and the DST savings multiplied by 1000 to
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* scale from seconds to milliseconds.
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*
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* 3. Countries. These have keys corresponding to the 2-letter ISO
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* country codes, with a percent sign prepended, e.g., "%US". Each
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* resource is an intvector listing the zones associated with the
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* given country. The special entry "%" corresponds to "no country",
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* that is, the category of zones assigned to no country in the Olson
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* DB.
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*
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* 4. Metadata. Metadata is stored under the key "_". It is an
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* intvector of length three containing the number of zones resources,
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* rule resources, and country resources. For the purposes of this
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* count, the metadata entry itself is considered a rule resource,
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* since its key begins with an underscore.
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*/
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class U_I18N_API OlsonTimeZone: public TimeZone {
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public:
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/**
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* Construct from a resource bundle.
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* @param top the top-level zoneinfo resource bundle. This is used
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* to lookup the rule that `res' may refer to, if there is one.
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* @param res the resource bundle of the zone to be constructed
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* @param ec input-output error code
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*/
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OlsonTimeZone(const UResourceBundle* top,
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const UResourceBundle* res, UErrorCode& ec);
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/**
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* Copy constructor
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*/
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OlsonTimeZone(const OlsonTimeZone& other);
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/**
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* Destructor
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*/
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virtual ~OlsonTimeZone();
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/**
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* Assignment operator
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*/
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OlsonTimeZone& operator=(const OlsonTimeZone& other);
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/**
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* Returns true if the two TimeZone objects are equal.
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*/
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virtual UBool operator==(const TimeZone& other) const;
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/**
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* TimeZone API.
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*/
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virtual TimeZone* clone() const;
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/**
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* TimeZone API.
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*/
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static UClassID U_EXPORT2 getStaticClassID();
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/**
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* TimeZone API.
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*/
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virtual UClassID getDynamicClassID() const;
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/**
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* TimeZone API. Do not call this; prefer getOffset(UDate,...).
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*/
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virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month,
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int32_t day, uint8_t dayOfWeek,
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int32_t millis, UErrorCode& ec) const;
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/**
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* TimeZone API. Do not call this; prefer getOffset(UDate,...).
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*/
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virtual int32_t getOffset(uint8_t era, int32_t year, int32_t month,
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int32_t day, uint8_t dayOfWeek,
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int32_t millis, int32_t monthLength,
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UErrorCode& ec) const;
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/**
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* TimeZone API.
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*/
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virtual void getOffset(UDate date, UBool local, int32_t& rawOffset,
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int32_t& dstOffset, UErrorCode& ec) const;
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/**
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* TimeZone API. This method has no effect since objects of this
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* class are quasi-immutable (the base class allows the ID to be
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* changed).
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*/
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virtual void setRawOffset(int32_t offsetMillis);
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/**
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* TimeZone API. For a historical zone, the raw offset can change
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* over time, so this API is not useful. In order to approximate
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* expected behavior, this method returns the raw offset for the
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* current moment in time.
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*/
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virtual int32_t getRawOffset() const;
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/**
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* TimeZone API. For a historical zone, whether DST is used or
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* not varies over time. In order to approximate expected
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* behavior, this method returns TRUE if DST is observed at any
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* point in the current year.
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*/
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virtual UBool useDaylightTime() const;
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/**
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* TimeZone API.
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*/
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virtual UBool inDaylightTime(UDate date, UErrorCode& ec) const;
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virtual int32_t getDSTSavings() const;
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protected:
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/**
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* Default constructor. Creates a time zone with an empty ID and
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* a fixed GMT offset of zero.
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*/
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OlsonTimeZone();
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private:
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void constructEmpty();
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int16_t findTransition(double time, UBool local) const;
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int32_t zoneOffset(int16_t index) const;
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int32_t rawOffset(int16_t index) const;
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int32_t dstOffset(int16_t index) const;
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/**
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* Number of transitions, 0..~370
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*/
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int16_t transitionCount;
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/**
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* Number of types, 1..255
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*/
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int16_t typeCount;
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/**
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* Time of each transition in seconds from 1970 epoch.
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* Length is transitionCount int32_t's.
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*/
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const int32_t *transitionTimes; // alias into res; do not delete
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/**
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* Offset from GMT in seconds for each type.
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* Length is typeCount int32_t's.
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*/
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const int32_t *typeOffsets; // alias into res; do not delete
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/**
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* Type description data, consisting of transitionCount uint8_t
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* type indices (from 0..typeCount-1).
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* Length is transitionCount int8_t's.
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*/
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const uint8_t *typeData; // alias into res; do not delete
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/**
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* The last year for which the transitions data are to be used
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* rather than the finalZone. If there is no finalZone, then this
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* is set to INT32_MAX. NOTE: This corresponds to the year _before_
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* the one indicated by finalMillis.
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*/
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int32_t finalYear;
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/**
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* The millis for the start of the first year for which finalZone
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* is to be used, or DBL_MAX if finalZone is 0. NOTE: This is
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* 0:00 GMT Jan 1, <finalYear + 1> (not <finalMillis>).
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*/
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double finalMillis;
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/**
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* A SimpleTimeZone that governs the behavior for years > finalYear.
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* If and only if finalYear == INT32_MAX then finalZone == 0.
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*/
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SimpleTimeZone *finalZone; // owned, may be NULL
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};
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inline int32_t
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OlsonTimeZone::zoneOffset(int16_t index) const {
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index <<= 1;
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return typeOffsets[index] + typeOffsets[index+1];
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}
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inline int32_t
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OlsonTimeZone::rawOffset(int16_t index) const {
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return typeOffsets[(uint32_t)(index << 1)];
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}
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inline int32_t
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OlsonTimeZone::dstOffset(int16_t index) const {
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return typeOffsets[(uint32_t)((index << 1) + 1)];
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}
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U_NAMESPACE_END
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#endif // !UCONFIG_NO_FORMATTING
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#endif // OLSONTZ_H
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//eof
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