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 // SPDX-FileCopyrightText: 2020 the KPhotoAlbum development team
 // SPDX-FileCopyrightText: 2022 - 2023 Johannes Zarl-Zierl <johannes@zarl-zierl.at>
 //
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #ifndef UTILITIES_FASTDATETIME_H
 #define UTILITIES_FASTDATETIME_H
 #include <QDate>
 #include <QDateTime>
 #include <QDebug>
 #include <QTime>
 
 namespace Utilities
 {
 
 /**
  * The FastDateTime class implements a datetime that is much faster
  * than QDateTime for comparing dates.  It caches the linear time
  * since the epoch for use in comparisons.  See
  * https://bugreports.qt.io/browse/QTBUG-41714 and
  * https://bugreports.qt.io/browse/QTBUG-75585 for an explanation
  * of why the standard QDateTime is extremely slow (on the order of
  * 1 usec per comparison).
  *
  * The distinguished value INT64_MIN is used to indicate an invalid
  * date/time.  Invalid date/times are passed to QDateTime for handling.
  */
 
 class FastDateTime
 {
 public:
     FastDateTime();
     FastDateTime(const QDate &d, const QTime &t, Qt::TimeSpec spec = Qt::LocalTime);
     FastDateTime(const QDate &d);
     FastDateTime(const FastDateTime &other) = default;
     FastDateTime(FastDateTime &&other) = default;
     // Needed for QDate(Y, M, D).startOfDay()
     FastDateTime(const QDateTime &other);
     ~FastDateTime() {};
 
     Q_DECL_CONSTEXPR bool operator==(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return m_msecsSinceEpoch == other.m_msecsSinceEpoch;
         else
             return m_dateTime == other.m_dateTime;
     }
     Q_DECL_CONSTEXPR bool operator!=(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return m_msecsSinceEpoch != other.m_msecsSinceEpoch;
         else
             return m_dateTime != other.m_dateTime;
     }
     Q_DECL_CONSTEXPR bool operator<(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return m_msecsSinceEpoch < other.m_msecsSinceEpoch;
         else
             return m_dateTime < other.m_dateTime;
     }
     Q_DECL_CONSTEXPR bool operator<=(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return m_msecsSinceEpoch <= other.m_msecsSinceEpoch;
         else
             return m_dateTime <= other.m_dateTime;
     }
     Q_DECL_CONSTEXPR bool operator>(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return m_msecsSinceEpoch > other.m_msecsSinceEpoch;
         else
             return m_dateTime > other.m_dateTime;
     }
     Q_DECL_CONSTEXPR bool operator>=(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return m_msecsSinceEpoch >= other.m_msecsSinceEpoch;
         else
             return m_dateTime >= other.m_dateTime;
     }
     bool isNull() const { return m_dateTime.isNull(); }
     bool isValid() const { return m_dateTime.isValid(); }
     QDate date() const { return m_dateTime.date(); }
     QTime time() const { return m_dateTime.time(); }
     QString toString(Qt::DateFormat format = Qt::TextDate) const { return m_dateTime.toString(format); }
     QString toString(QStringView format) const
     {
         return m_dateTime.toString(format);
     }
     qint64 secsTo(const FastDateTime &other) const
     {
         if (isOK() && other.isOK())
             return (other.m_msecsSinceEpoch - m_msecsSinceEpoch) / 1000;
         else
             return secsTo(other);
     }
     qint64 toSecsSinceEpoch() const
     {
         if (isOK())
             return m_msecsSinceEpoch / 1000;
         else
             return m_dateTime.toSecsSinceEpoch();
     }
     FastDateTime &operator=(const Utilities::FastDateTime &other) = default;
     FastDateTime &operator=(Utilities::FastDateTime &&other) = default;
 
     Q_REQUIRED_RESULT FastDateTime addDays(qint64 days) const;
     Q_REQUIRED_RESULT FastDateTime addMonths(qint64 months) const;
     Q_REQUIRED_RESULT FastDateTime addYears(qint64 years) const;
     Q_REQUIRED_RESULT FastDateTime addSecs(qint64 secs) const;
 
     static FastDateTime currentDateTime();
     static FastDateTime fromString(const QString &s, Qt::DateFormat f = Qt::TextDate);
 
 private:
     Q_DECL_CONSTEXPR bool isOK() const
     {
         return m_msecsSinceEpoch > INT64_MIN;
     }
     QDateTime m_dateTime;
     qint64 m_msecsSinceEpoch;
 };
 }
 
 QDebug operator<<(QDebug debug, const Utilities::FastDateTime &d);
 
 #endif /* UTILITIES_FASTDATETIME_H */
 
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