129 lines
4.6 KiB
C++
129 lines
4.6 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2018 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qglobal.h"
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#include "qjuliancalendar_p.h"
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#include "qromancalendar_data_p.h"
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#include "qcalendarmath_p.h"
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#include <QtCore/qmath.h>
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#include <QtCore/qlocale.h>
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#include <QtCore/qdatetime.h>
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QT_BEGIN_NAMESPACE
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using namespace QRoundingDown;
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/*!
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\since 5.14
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\class QJulianCalendar
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\inmodule QtCore
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\brief The QJulianCalendar class provides Julian calendar system
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implementation.
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\section1 Julian Calendar
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The Julian calendar, proposed by Julius Caesar in 46 BC (708 AUC), was a
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reform of the Roman calendar. It took effect on 1 January 45 BC (AUC 709),
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by edict. It was the predominant calendar in the Roman world, most of
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Europe, and in European settlements in the Americas and elsewhere, until it
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was refined and gradually replaced by the Gregorian calendar,
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promulgated in 1582 by Pope Gregory XIII.
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The Julian calendar gains against the mean tropical year at the rate of one
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day in 128 years. For the Gregorian calendar, the figure is one day in
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3030 years. The difference in the average length of the year
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between Julian (365.25 days) and Gregorian (365.2425 days) is 0.002%.
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Source: \l {https://en.wikipedia.org/wiki/Julian_calendar}{Wikipedia page on
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Julian Calendar}
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*/
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QJulianCalendar::QJulianCalendar()
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: QRomanCalendar(QStringLiteral("Julian"), QCalendar::System::Julian) {}
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QString QJulianCalendar::name() const
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{
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return QStringLiteral("Julian");
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}
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QCalendar::System QJulianCalendar::calendarSystem() const
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{
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return QCalendar::System::Julian;
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}
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bool QJulianCalendar::isLeapYear(int year) const
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{
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if (year == QCalendar::Unspecified || !year)
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return false;
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return qMod(year < 0 ? year + 1 : year, 4) == 0;
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}
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// Julian Day 0 was January the first in the proleptic Julian calendar's 4713 BC
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bool QJulianCalendar::dateToJulianDay(int year, int month, int day, qint64 *jd) const
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{
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Q_ASSERT(jd);
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if (!isDateValid(year, month, day))
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return false;
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if (year < 0)
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++year;
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const qint64 c0 = month < 3 ? -1 : 0;
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const qint64 j1 = qDiv(1461 * (year + c0), 4);
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const qint64 j2 = qDiv(153 * month - 1836 * c0 - 457, 5);
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*jd = j1 + j2 + day + 1721117;
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return true;
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}
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QCalendar::YearMonthDay QJulianCalendar::julianDayToDate(qint64 jd) const
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{
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const qint64 y2 = jd - 1721118;
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const qint64 k2 = 4 * y2 + 3;
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const qint64 k1 = 5 * qDiv(qMod(k2, 1461), 4) + 2;
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const qint64 x1 = qDiv(k1, 153);
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const qint64 c0 = qDiv(x1 + 2, 12);
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const int y = qint16(qDiv(k2, 1461) + c0);
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const int month = quint8(x1 - 12 * c0 + 3);
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const int day = qDiv(qMod(k1, 153), 5) + 1;
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return QCalendar::YearMonthDay(y > 0 ? y : y - 1, month, day);
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}
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QT_END_NAMESPACE
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