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Filename : basictz.h
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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
* Copyright (C) 2007-2013, International Business Machines Corporation and
* others. All Rights Reserved.
*******************************************************************************
*/
#ifndef BASICTZ_H
#define BASICTZ_H

/**
 * \file 
 * \brief C++ API: ICU TimeZone base class
 */

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#if !UCONFIG_NO_FORMATTING

#include "unicode/timezone.h"
#include "unicode/tzrule.h"
#include "unicode/tztrans.h"

U_NAMESPACE_BEGIN

// forward declarations
class UVector;

/**
 * <code>BasicTimeZone</code> is an abstract class extending <code>TimeZone</code>.
 * This class provides some additional methods to access time zone transitions and rules.
 * All ICU <code>TimeZone</code> concrete subclasses extend this class.
 * @stable ICU 3.8
 */
class U_I18N_API BasicTimeZone: public TimeZone {
public:
    /**
     * Destructor.
     * @stable ICU 3.8
     */
    virtual ~BasicTimeZone();

    /**
     * Clones this object polymorphically.
     * The caller owns the result and should delete it when done.
     * @return clone, or nullptr if an error occurred
     * @stable ICU 3.8
     */
    virtual BasicTimeZone* clone() const override = 0;

    /**
     * Gets the first time zone transition after the base time.
     * @param base      The base time.
     * @param inclusive Whether the base time is inclusive or not.
     * @param result    Receives the first transition after the base time.
     * @return  true if the transition is found.
     * @stable ICU 3.8
     */
    virtual UBool getNextTransition(UDate base, UBool inclusive, TimeZoneTransition& result) const = 0;

    /**
     * Gets the most recent time zone transition before the base time.
     * @param base      The base time.
     * @param inclusive Whether the base time is inclusive or not.
     * @param result    Receives the most recent transition before the base time.
     * @return  true if the transition is found.
     * @stable ICU 3.8
     */
    virtual UBool getPreviousTransition(UDate base, UBool inclusive, TimeZoneTransition& result) const = 0;

    /**
     * Checks if the time zone has equivalent transitions in the time range.
     * This method returns true when all of transition times, from/to standard
     * offsets and DST savings used by this time zone match the other in the
     * time range.
     * @param tz    The <code>BasicTimeZone</code> object to be compared with.
     * @param start The start time of the evaluated time range (inclusive)
     * @param end   The end time of the evaluated time range (inclusive)
     * @param ignoreDstAmount
     *              When true, any transitions with only daylight saving amount
     *              changes will be ignored, except either of them is zero.
     *              For example, a transition from rawoffset 3:00/dstsavings 1:00
     *              to rawoffset 2:00/dstsavings 2:00 is excluded from the comparison,
     *              but a transition from rawoffset 2:00/dstsavings 1:00 to
     *              rawoffset 3:00/dstsavings 0:00 is included.
     * @param ec    Output param to filled in with a success or an error.
     * @return      true if the other time zone has the equivalent transitions in the
     *              time range.
     * @stable ICU 3.8
     */
    virtual UBool hasEquivalentTransitions(const BasicTimeZone& tz, UDate start, UDate end,
        UBool ignoreDstAmount, UErrorCode& ec) const;

    /**
     * Returns the number of <code>TimeZoneRule</code>s which represents time transitions,
     * for this time zone, that is, all <code>TimeZoneRule</code>s for this time zone except
     * <code>InitialTimeZoneRule</code>.  The return value range is 0 or any positive value.
     * @param status    Receives error status code.
     * @return The number of <code>TimeZoneRule</code>s representing time transitions.
     * @stable ICU 3.8
     */
    virtual int32_t countTransitionRules(UErrorCode& status) const = 0;

    /**
     * Gets the <code>InitialTimeZoneRule</code> and the set of <code>TimeZoneRule</code>
     * which represent time transitions for this time zone.  On successful return,
     * the argument initial points to non-nullptr <code>InitialTimeZoneRule</code> and
     * the array trsrules is filled with 0 or multiple <code>TimeZoneRule</code>
     * instances up to the size specified by trscount.  The results are referencing the
     * rule instance held by this time zone instance.  Therefore, after this time zone
     * is destructed, they are no longer available.
     * @param initial       Receives the initial timezone rule
     * @param trsrules      Receives the timezone transition rules
     * @param trscount      On input, specify the size of the array 'transitions' receiving
     *                      the timezone transition rules.  On output, actual number of
     *                      rules filled in the array will be set.
     * @param status        Receives error status code.
     * @stable ICU 3.8
     */
    virtual void getTimeZoneRules(const InitialTimeZoneRule*& initial,
        const TimeZoneRule* trsrules[], int32_t& trscount, UErrorCode& status) const = 0;

    /**
     * Gets the set of time zone rules valid at the specified time.  Some known external time zone
     * implementations are not capable to handle historic time zone rule changes.  Also some
     * implementations can only handle certain type of rule definitions.
     * If this time zone does not use any daylight saving time within about 1 year from the specified
     * time, only the <code>InitialTimeZone</code> is returned.  Otherwise, the rule for standard
     * time and daylight saving time transitions are returned in addition to the
     * <code>InitialTimeZoneRule</code>.  The standard and daylight saving time transition rules are
     * represented by <code>AnnualTimeZoneRule</code> with <code>DateTimeRule::DOW</code> for its date
     * rule and <code>DateTimeRule::WALL_TIME</code> for its time rule.  Because daylight saving time
     * rule is changing time to time in many time zones and also mapping a transition time rule to
     * different type is lossy transformation, the set of rules returned by this method may be valid
     * for short period of time.
     * The time zone rule objects returned by this method is owned by the caller, so the caller is
     * responsible for deleting them after use.
     * @param date      The date used for extracting time zone rules.
     * @param initial   Receives the <code>InitialTimeZone</code>, always not nullptr.
     * @param std       Receives the <code>AnnualTimeZoneRule</code> for standard time transitions.
     *                  When this time time zone does not observe daylight saving times around the
     *                  specified date, nullptr is set.
     * @param dst       Receives the <code>AnnualTimeZoneRule</code> for daylight saving time
     *                  transitions.  When this time zone does not observer daylight saving times
     *                  around the specified date, nullptr is set.
     * @param status    Receives error status code.
     * @stable ICU 3.8
     */
    virtual void getSimpleRulesNear(UDate date, InitialTimeZoneRule*& initial,
        AnnualTimeZoneRule*& std, AnnualTimeZoneRule*& dst, UErrorCode& status) const;

    /**
     * Get time zone offsets from local wall time.
     * @stable ICU 69
     */
    virtual void getOffsetFromLocal(
        UDate date, UTimeZoneLocalOption nonExistingTimeOpt,
        UTimeZoneLocalOption duplicatedTimeOpt, int32_t& rawOffset,
        int32_t& dstOffset, UErrorCode& status) const;


#ifndef U_HIDE_INTERNAL_API
    /**
     * The time type option bit flags used by getOffsetFromLocal
     * @internal
     */
    enum {
        kStandard = 0x01,
        kDaylight = 0x03,
        kFormer = 0x04, /* UCAL_TZ_LOCAL_FORMER */
        kLatter = 0x0C  /* UCAL_TZ_LOCAL_LATTER */
    };

    /**
     * Get time zone offsets from local wall time.
     * @internal
     */
    void getOffsetFromLocal(UDate date, int32_t nonExistingTimeOpt, int32_t duplicatedTimeOpt,
        int32_t& rawOffset, int32_t& dstOffset, UErrorCode& status) const;
#endif  /* U_HIDE_INTERNAL_API */

protected:

#ifndef U_HIDE_INTERNAL_API
    /**
     * A time type option bit mask used by getOffsetFromLocal.
     * @internal
     */
    static constexpr int32_t kStdDstMask = kDaylight;
    /**
     * A time type option bit mask used by getOffsetFromLocal.
     * @internal
     */
    static constexpr int32_t kFormerLatterMask = kLatter;
#endif  /* U_HIDE_INTERNAL_API */

    /**
     * Default constructor.
     * @stable ICU 3.8
     */
    BasicTimeZone();

    /**
     * Construct a timezone with a given ID.
     * @param id a system time zone ID
     * @stable ICU 3.8
     */
    BasicTimeZone(const UnicodeString &id);

    /**
     * Copy constructor.
     * @param source the object to be copied.
     * @stable ICU 3.8
     */
    BasicTimeZone(const BasicTimeZone& source);

    /**
     * Copy assignment.
     * @stable ICU 3.8
     */
    BasicTimeZone& operator=(const BasicTimeZone&) = default;

    /**
     * Gets the set of TimeZoneRule instances applicable to the specified time and after.
     * @param start     The start date used for extracting time zone rules
     * @param initial   Output parameter, receives the InitialTimeZone.
     *                  Always not nullptr (except in case of error)
     * @param transitionRules   Output parameter, a UVector of transition rules.
     *                  May be nullptr, if there are no transition rules.
     *                  The caller owns the returned vector; the UVector owns the rules.
     * @param status    Receives error status code
     */
    void getTimeZoneRulesAfter(UDate start, InitialTimeZoneRule*& initial, UVector*& transitionRules,
        UErrorCode& status) const;
};

U_NAMESPACE_END

#endif /* #if !UCONFIG_NO_FORMATTING */

#endif /* U_SHOW_CPLUSPLUS_API */

#endif // BASICTZ_H

//eof