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| |
| #include "qgregoriancalendar_p.h" |
| #include "qcalendarmath_p.h" |
| #include <QtCore/qdatetime.h> |
| |
| QT_BEGIN_NAMESPACE |
| |
| using namespace QRoundingDown; |
| |
| /*! |
| \since 5.14 |
| |
| \class QGregorianCalendar |
| \inmodule QtCore |
| \brief The QGregorianCalendar class implements the Gregorian calendar. |
| |
| \section1 The Gregorian Calendar |
| |
| The Gregorian calendar is a refinement of the earlier Julian calendar, |
| itself a late form of the Roman calendar. It is widely used. |
| |
| \sa QRomanCalendar, QJulianCalendar, QCalendar |
| */ |
| |
| QGregorianCalendar::QGregorianCalendar() |
| : QRomanCalendar(QStringLiteral("Gregorian"), QCalendar::System::Gregorian) |
| { |
| registerAlias(QStringLiteral("gregory")); |
| } |
| |
| QString QGregorianCalendar::name() const |
| { |
| return QStringLiteral("Gregorian"); |
| } |
| |
| QCalendar::System QGregorianCalendar::calendarSystem() const |
| { |
| return QCalendar::System::Gregorian; |
| } |
| |
| bool QGregorianCalendar::isLeapYear(int year) const |
| { |
| return leapTest(year); |
| } |
| |
| bool QGregorianCalendar::leapTest(int year) |
| { |
| if (year == QCalendar::Unspecified) |
| return false; |
| |
| // No year 0 in Gregorian calendar, so -1, -5, -9 etc are leap years |
| if (year < 1) |
| ++year; |
| |
| return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0); |
| } |
| |
| // Duplicating code from QRomanCalendar, but inlining isLeapYear() as leapTest(): |
| int QGregorianCalendar::monthLength(int month, int year) |
| { |
| if (month < 1 || month > 12) |
| return 0; |
| |
| if (month == 2) |
| return leapTest(year) ? 29 : 28; |
| |
| return 30 | ((month & 1) ^ (month >> 3)); |
| } |
| |
| bool QGregorianCalendar::validParts(int year, int month, int day) |
| { |
| return year && 0 < day && day <= monthLength(month, year); |
| } |
| |
| int QGregorianCalendar::weekDayOfJulian(qint64 jd) |
| { |
| return qMod(jd, 7) + 1; |
| } |
| |
| bool QGregorianCalendar::dateToJulianDay(int year, int month, int day, qint64 *jd) const |
| { |
| return julianFromParts(year, month, day, jd); |
| } |
| |
| bool QGregorianCalendar::julianFromParts(int year, int month, int day, qint64 *jd) |
| { |
| Q_ASSERT(jd); |
| if (!validParts(year, month, day)) |
| return false; |
| |
| if (year < 0) |
| ++year; |
| |
| /* |
| * Math from The Calendar FAQ at http://www.tondering.dk/claus/cal/julperiod.php |
| * This formula is correct for all julian days, when using mathematical integer |
| * division (round to negative infinity), not c++11 integer division (round to zero) |
| */ |
| int a = month < 3 ? 1 : 0; |
| qint64 y = qint64(year) + 4800 - a; |
| int m = month + 12 * a - 3; |
| *jd = day + qDiv(153 * m + 2, 5) - 32045 |
| + 365 * y + qDiv(y, 4) - qDiv(y, 100) + qDiv(y, 400); |
| return true; |
| } |
| |
| QCalendar::YearMonthDay QGregorianCalendar::julianDayToDate(qint64 jd) const |
| { |
| return partsFromJulian(jd); |
| } |
| |
| QCalendar::YearMonthDay QGregorianCalendar::partsFromJulian(qint64 jd) |
| { |
| /* |
| * Math from The Calendar FAQ at http://www.tondering.dk/claus/cal/julperiod.php |
| * This formula is correct for all julian days, when using mathematical integer |
| * division (round to negative infinity), not c++11 integer division (round to zero) |
| */ |
| qint64 a = jd + 32044; |
| qint64 b = qDiv(4 * a + 3, 146097); |
| int c = a - qDiv(146097 * b, 4); |
| |
| int d = qDiv(4 * c + 3, 1461); |
| int e = c - qDiv(1461 * d, 4); |
| int m = qDiv(5 * e + 2, 153); |
| |
| int y = 100 * b + d - 4800 + qDiv(m, 10); |
| |
| // Adjust for no year 0 |
| int year = y > 0 ? y : y - 1; |
| int month = m + 3 - 12 * qDiv(m, 10); |
| int day = e - qDiv(153 * m + 2, 5) + 1; |
| |
| return QCalendar::YearMonthDay(year, month, day); |
| } |
| |
| QT_END_NAMESPACE |