include/QtCore/qtimezone.h

0001 // Copyright (C) 2017 The Qt Company Ltd.
0002 // Copyright (C) 2013 John Layt <jlayt@kde.org>
0003 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
0004
0005 #ifndef QTIMEZONE_H
0006 #define QTIMEZONE_H
0007
0008 #include <QtCore/qcompare.h>
0009 #include <QtCore/qdatetime.h>
0010 #include <QtCore/qlocale.h>
0011 #include <QtCore/qswap.h>
0012 #include <QtCore/qtclasshelpermacros.h>
0013
0014 #include <chrono>
0015
0016 #if QT_CONFIG(timezone) && (defined(Q_OS_DARWIN) || defined(Q_QDOC))
0017 Q_FORWARD_DECLARE_CF_TYPE(CFTimeZone);
0018 Q_FORWARD_DECLARE_OBJC_CLASS(NSTimeZone);
0019 #endif
0020
0021 QT_BEGIN_NAMESPACE
0022
0023 class QTimeZonePrivate;
0024
0025 class Q_CORE_EXPORT QTimeZone
0026 {
0027     struct ShortData
0028     {
0029 #if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
0030         quintptr mode : 2;
0031 #endif
0032         qintptr offset : sizeof(void *) * 8 - 2;
0033
0034 #if Q_BYTE_ORDER == Q_BIG_ENDIAN
0035         quintptr mode : 2;
0036 #endif
0037
0038         // mode is a cycled Qt::TimeSpec, (int(spec) + 1) % 4, so that zero
0039         // (lowest bits of a pointer) matches spec being Qt::TimeZone, for which
0040         // Data holds a QTZP pointer instead of ShortData.
0041         // Passing Qt::TimeZone gets the equivalent of a null QTZP; it is not short.
0042         constexpr ShortData(Qt::TimeSpec spec, int secondsAhead = 0)
0043 #if Q_BYTE_ORDER == Q_BIG_ENDIAN
0044             : offset(spec == Qt::OffsetFromUTC ? secondsAhead : 0),
0045               mode((int(spec) + 1) & 3)
0046 #else
0047             : mode((int(spec) + 1) & 3),
0048               offset(spec == Qt::OffsetFromUTC ? secondsAhead : 0)
0049 #endif
0050         {
0051         }
0052         friend constexpr bool operator==(ShortData lhs, ShortData rhs)
0053         { return lhs.mode == rhs.mode && lhs.offset == rhs.offset; }
0054         constexpr Qt::TimeSpec spec() const { return Qt::TimeSpec((mode + 3) & 3); }
0055     };
0056
0057     union Data
0058     {
0059         Data() noexcept;
0060         Data(ShortData sd) : s(sd) {}
0061         Data(const Data &other) noexcept;
0062         Data(Data &&other) noexcept : d(std::exchange(other.d, nullptr)) {}
0063         Data &operator=(const Data &other) noexcept;
0064         Data &operator=(Data &&other) noexcept { swap(other); return *this; }
0065         ~Data();
0066
0067         void swap(Data &other) noexcept { qt_ptr_swap(d, other.d); }
0068         // isShort() is equivalent to s.spec() != Qt::TimeZone
0069         bool isShort() const { return s.mode; } // a.k.a. quintptr(d) & 3
0070
0071         // Typse must support: out << wrap("C-strings");
0072         template <typename Stream, typename Wrap>
0073         void serialize(Stream &out, const Wrap &wrap) const;
0074
0075         Data(QTimeZonePrivate *dptr) noexcept;
0076         Data &operator=(QTimeZonePrivate *dptr) noexcept;
0077         const QTimeZonePrivate *operator->() const { Q_ASSERT(!isShort()); return d; }
0078         QTimeZonePrivate *operator->() { Q_ASSERT(!isShort()); return d; }
0079
0080         QTimeZonePrivate *d = nullptr;
0081         ShortData s;
0082     };
0083     QTimeZone(ShortData sd) : d(sd) {}
0084
0085 public:
0086     // Sane UTC offsets range from -16 to +16 hours:
0087     static constexpr int MinUtcOffsetSecs = -16 * 3600;
0088     // No known modern zone > 12 hrs West of Greenwich.
0089     // Until 1844, Asia/Manila (in The Philippines) was at 15:56 West.
0090     static constexpr int MaxUtcOffsetSecs = +16 * 3600;
0091     // No known modern zone > 14 hrs East of Greenwich.
0092     // Until 1867, America/Metlakatla (in Alaska) was at 15:13:42 East.
0093
0094     enum Initialization { LocalTime, UTC };
0095
0096     QTimeZone() noexcept;
0097     Q_IMPLICIT QTimeZone(Initialization spec) noexcept
0098         : d(ShortData(spec == UTC ? Qt::UTC : Qt::LocalTime)) {}
0099
0100 #if QT_CONFIG(timezone)
0101     explicit QTimeZone(int offsetSeconds);
0102     explicit QTimeZone(const QByteArray &ianaId);
0103     QTimeZone(const QByteArray &zoneId, int offsetSeconds, const QString &name,
0104               const QString &abbreviation, QLocale::Territory territory = QLocale::AnyTerritory,
0105               const QString &comment = QString());
0106 #endif // timezone backends
0107
0108     QTimeZone(const QTimeZone &other) noexcept;
0109     QTimeZone(QTimeZone &&other) noexcept : d(std::move(other.d)) {}
0110     ~QTimeZone();
0111
0112     QTimeZone &operator=(const QTimeZone &other);
0113     QT_MOVE_ASSIGNMENT_OPERATOR_IMPL_VIA_PURE_SWAP(QTimeZone)
0114
0115     void swap(QTimeZone &other) noexcept
0116     { d.swap(other.d); }
0117
0118 #if QT_CORE_REMOVED_SINCE(6, 7)
0119     bool operator==(const QTimeZone &other) const;
0120     bool operator!=(const QTimeZone &other) const;
0121 #endif
0122
0123     bool isValid() const;
0124
0125     static QTimeZone fromDurationAheadOfUtc(std::chrono::seconds offset)
0126     {
0127         return QTimeZone((offset.count() >= MinUtcOffsetSecs && offset.count() <= MaxUtcOffsetSecs)
0128                          ? ShortData(offset.count() ? Qt::OffsetFromUTC : Qt::UTC,
0129                                      int(offset.count()))
0130                          : ShortData(Qt::TimeZone));
0131     }
0132     static QTimeZone fromSecondsAheadOfUtc(int offset)
0133     {
0134         return fromDurationAheadOfUtc(std::chrono::seconds{offset});
0135     }
0136     constexpr Qt::TimeSpec timeSpec() const noexcept { return d.s.spec(); }
0137     constexpr int fixedSecondsAheadOfUtc() const noexcept
0138     { return timeSpec() == Qt::OffsetFromUTC ? int(d.s.offset) : 0; }
0139
0140     static constexpr bool isUtcOrFixedOffset(Qt::TimeSpec spec) noexcept
0141     { return spec == Qt::UTC || spec == Qt::OffsetFromUTC; }
0142     constexpr bool isUtcOrFixedOffset() const noexcept { return isUtcOrFixedOffset(timeSpec()); }
0143
0144 #if QT_CONFIG(timezone)
0145     QTimeZone asBackendZone() const;
0146
0147     enum TimeType {
0148         StandardTime = 0,
0149         DaylightTime = 1,
0150         GenericTime = 2
0151     };
0152
0153     enum NameType {
0154         DefaultName = 0,
0155         LongName = 1,
0156         ShortName = 2,
0157         OffsetName = 3
0158     };
0159
0160     struct OffsetData {
0161         QString abbreviation;
0162         QDateTime atUtc;
0163         int offsetFromUtc;
0164         int standardTimeOffset;
0165         int daylightTimeOffset;
0166     };
0167     typedef QList<OffsetData> OffsetDataList;
0168
0169     bool hasAlternativeName(QByteArrayView alias) const;
0170     QByteArray id() const;
0171     QLocale::Territory territory() const;
0172 #  if QT_DEPRECATED_SINCE(6, 6)
0173     QT_DEPRECATED_VERSION_X_6_6("Use territory() instead")
0174     QLocale::Country country() const;
0175 #  endif
0176     QString comment() const;
0177
0178     QString displayName(const QDateTime &atDateTime, NameType nameType = DefaultName,
0179                         const QLocale &locale = QLocale()) const;
0180     QString displayName(TimeType timeType, NameType nameType = DefaultName,
0181                         const QLocale &locale = QLocale()) const;
0182     QString abbreviation(const QDateTime &atDateTime) const;
0183
0184     int offsetFromUtc(const QDateTime &atDateTime) const;
0185     int standardTimeOffset(const QDateTime &atDateTime) const;
0186     int daylightTimeOffset(const QDateTime &atDateTime) const;
0187
0188     bool hasDaylightTime() const;
0189     bool isDaylightTime(const QDateTime &atDateTime) const;
0190
0191     OffsetData offsetData(const QDateTime &forDateTime) const;
0192
0193     bool hasTransitions() const;
0194     OffsetData nextTransition(const QDateTime &afterDateTime) const;
0195     OffsetData previousTransition(const QDateTime &beforeDateTime) const;
0196     OffsetDataList transitions(const QDateTime &fromDateTime, const QDateTime &toDateTime) const;
0197
0198     static QByteArray systemTimeZoneId();
0199     static QTimeZone systemTimeZone();
0200     static QTimeZone utc();
0201
0202     static bool isTimeZoneIdAvailable(const QByteArray &ianaId);
0203
0204     static QList<QByteArray> availableTimeZoneIds();
0205     static QList<QByteArray> availableTimeZoneIds(QLocale::Territory territory);
0206     static QList<QByteArray> availableTimeZoneIds(int offsetSeconds);
0207
0208     static QByteArray ianaIdToWindowsId(const QByteArray &ianaId);
0209     static QByteArray windowsIdToDefaultIanaId(const QByteArray &windowsId);
0210     static QByteArray windowsIdToDefaultIanaId(const QByteArray &windowsId,
0211                                                QLocale::Territory territory);
0212     static QList<QByteArray> windowsIdToIanaIds(const QByteArray &windowsId);
0213     static QList<QByteArray> windowsIdToIanaIds(const QByteArray &windowsId,
0214                                                 QLocale::Territory territory);
0215
0216 #  if defined(Q_OS_DARWIN) || defined(Q_QDOC)
0217     static QTimeZone fromCFTimeZone(CFTimeZoneRef timeZone);
0218     CFTimeZoneRef toCFTimeZone() const Q_DECL_CF_RETURNS_RETAINED;
0219     static QTimeZone fromNSTimeZone(const NSTimeZone *timeZone);
0220     NSTimeZone *toNSTimeZone() const Q_DECL_NS_RETURNS_AUTORELEASED;
0221 #  endif
0222
0223 #  if __cpp_lib_chrono >= 201907L || defined(Q_QDOC)
0224     QT_POST_CXX17_API_IN_EXPORTED_CLASS
0225     static QTimeZone fromStdTimeZonePtr(const std::chrono::time_zone *timeZone)
0226     {
0227         if (!timeZone)
0228             return QTimeZone();
0229         const std::string_view timeZoneName = timeZone->name();
0230         return QTimeZone(QByteArrayView(timeZoneName).toByteArray());
0231     }
0232 #  endif
0233 #endif // feature timezone
0234 private:
0235     friend Q_CORE_EXPORT bool comparesEqual(const QTimeZone &lhs, const QTimeZone &rhs) noexcept;
0236     Q_DECLARE_EQUALITY_COMPARABLE(QTimeZone)
0237
0238 #ifndef QT_NO_DATASTREAM
0239     friend Q_CORE_EXPORT QDataStream &operator<<(QDataStream &ds, const QTimeZone &tz);
0240 #endif
0241 #ifndef QT_NO_DEBUG_STREAM
0242     friend Q_CORE_EXPORT QDebug operator<<(QDebug dbg, const QTimeZone &tz);
0243 #endif
0244     QTimeZone(QTimeZonePrivate &dd);
0245     friend class QTimeZonePrivate;
0246     friend class QDateTime;
0247     friend class QDateTimePrivate;
0248     Data d;
0249 };
0250
0251 #if QT_CONFIG(timezone)
0252 Q_DECLARE_TYPEINFO(QTimeZone::OffsetData, Q_RELOCATABLE_TYPE);
0253 #endif
0254 Q_DECLARE_SHARED(QTimeZone)
0255
0256 #ifndef QT_NO_DATASTREAM
0257 Q_CORE_EXPORT QDataStream &operator<<(QDataStream &ds, const QTimeZone &tz);
0258 Q_CORE_EXPORT QDataStream &operator>>(QDataStream &ds, QTimeZone &tz);
0259 #endif
0260
0261 #ifndef QT_NO_DEBUG_STREAM
0262 Q_CORE_EXPORT QDebug operator<<(QDebug dbg, const QTimeZone &tz);
0263 #endif
0264
0265 #if QT_CONFIG(timezone) && __cpp_lib_chrono >= 201907L
0266 // zoned_time
0267 template <typename> // QT_POST_CXX17_API_IN_EXPORTED_CLASS
0268 inline QDateTime QDateTime::fromStdZonedTime(const std::chrono::zoned_time<
0269                                                 std::chrono::milliseconds,
0270                                                 const std::chrono::time_zone *
0271                                              > &time)
0272 {
0273     const auto sysTime = time.get_sys_time();
0274     const QTimeZone timeZone = QTimeZone::fromStdTimeZonePtr(time.get_time_zone());
0275     return fromMSecsSinceEpoch(sysTime.time_since_epoch().count(), timeZone);
0276 }
0277 #endif
0278
0279 QT_END_NAMESPACE
0280
0281 #endif // QTIMEZONE_H