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39
40#include "qglobal.h"
41#include "qjalalicalendar_p.h"
42#include "qjalalicalendar_data_p.h"
43#include "qcalendarmath_p.h"
44#include <QtCore/qmath.h>
45
46QT_BEGIN_NAMESPACE
47
48using namespace QRoundingDown;
49
50// Constants
51
52static const qint64 cycleDays = 1029983;
53static const int cycleYears = 2820;
54static const double yearLength = 365.24219858156028368; // 365 + leapRatio;
55static const qint64 jalaliEpoch = 2121446; // 475/01/01 AP, start of 2820 cycle
56
57// Calendar implementation
58
59static inline int cycle(qint64 jdn)
60{
61 return qDiv(jdn - jalaliEpoch, cycleDays);
62}
63
64qint64 cycleStart(int cycleNo)
65{
66 return jalaliEpoch + cycleNo * cycleDays;
67}
68
69qint64 firstDayOfYear(int year, int cycleNo)
70{
71 qint64 firstDOYinEra = static_cast<qint64>(qFloor(year * yearLength));
72 return jalaliEpoch + cycleNo * cycleDays + firstDOYinEra;
73}
74
75/*!
76 \since 5.14
77
78 \class QJalaliCalendar
79 \inmodule QtCore
80 \brief The QJalaliCalendar class provides Jalali (Hijri Shamsi) calendar
81 system implementation.
82
83 \section1 Solar Hijri Calendar System
84
85 The Solar Hijri calendar, also called the Solar Hejri calendar, Shamsi
86 Hijri calendar or Jalali calendar, is the official calendar of Iran and
87 Afghanistan. It begins on the vernal equinox (Nowruz) as determined by
88 astronomical calculation for the Iran Standard Time meridian
89 (52.5°E or GMT+3.5h). This determination of starting moment is more accurate
90 than the Gregorian calendar for predicting the date of the vernal equinox,
91 because it uses astronomical observations rather than mathematical rules.
92
93 \section2 Calendar Organization
94
95 Each of the twelve months corresponds with a zodiac sign. The first six
96 months have 31 days, the next five have 30 days, and the last month has 29
97 days in usual years but 30 days in leap years. The New Year's Day always
98 falls on the March equinox.
99
100 \section2 Leap Year Rules
101
102 The Solar Hijri calendar produces a five-year leap year interval after about
103 every seven four-year leap year intervals. It usually follows a 33-year
104 cycle with occasional interruptions by single 29-year or 37-year subcycles.
105 The reason for this behavior is that it tracks the observed vernal equinox.
106 By contrast, some less accurate predictive algorithms are in use based
107 on confusion between the average tropical year (365.2422 days, approximated
108 with near 128-year cycles or 2820-year great cycles) and the mean interval
109 between spring equinoxes (365.2424 days, approximated with a near 33-year
110 cycle).
111
112 Source: \l {https://en.wikipedia.org/wiki/Solar_Hijri_calendar}{Wikipedia
113 page on Solar Hijri Calendar}
114 */
115
116QJalaliCalendar::QJalaliCalendar()
117 : QCalendarBackend(QStringLiteral("Jalali"), QCalendar::System::Jalali)
118{
119 registerAlias(QStringLiteral("Persian"));
120}
121
122QString QJalaliCalendar::name() const
123{
124 return QStringLiteral("Jalali");
125}
126
127QCalendar::System QJalaliCalendar::calendarSystem() const
128{
129 return QCalendar::System::Jalali;
130}
131
132bool QJalaliCalendar::isLeapYear(int year) const
133{
134 if (year == QCalendar::Unspecified)
135 return false;
136 if (year < 0)
137 year++;
138 return qMod((year + 2346) * 683, 2820) < 683;
139}
140
141bool QJalaliCalendar::isLunar() const
142{
143 return false;
144}
145
146bool QJalaliCalendar::isLuniSolar() const
147{
148 return false;
149}
150
151bool QJalaliCalendar::isSolar() const
152{
153 return true;
154}
155
156bool QJalaliCalendar::dateToJulianDay(int year, int month, int day, qint64 *jd) const
157{
158 Q_ASSERT(jd);
159 if (!isDateValid(year, month, day))
160 return false;
161
162 const int y = year - (year < 0 ? 474 : 475);
163 const int c = qDiv(y, cycleYears);
164 const int yearInCycle = y - c * cycleYears;
165 int dayInYear = day;
166 for (int i = 1; i < month; ++i)
167 dayInYear += daysInMonth(i, year);
168 *jd = firstDayOfYear(yearInCycle, c) + dayInYear - 1;
169 return true;
170}
171
172QCalendar::YearMonthDay QJalaliCalendar::julianDayToDate(qint64 jd) const
173{
174 const int c = cycle(jd);
175 int yearInCycle = qFloor((jd - cycleStart(c)) / yearLength);
176 int year = yearInCycle + 475 + c * cycleYears;
177 int day = jd - firstDayOfYear(yearInCycle, c) + 1;
178 if (day > daysInYear(year <= 0 ? year - 1 : year)) {
179 year++;
180 day = 1;
181 }
182 if (year <= 0)
183 year--;
184 int month;
185 for (month = 1; month < 12; ++month) {
186 const int last = daysInMonth(month, year);
187 if (day <= last)
188 break;
189 day -= last;
190 }
191 return QCalendar::YearMonthDay(year, month, day);
192}
193
194int QJalaliCalendar::daysInMonth(int month, int year) const
195{
196 if (year && month > 0 && month <= 12)
197 return month < 7 ? 31 : month < 12 || isLeapYear(year) ? 30 : 29;
198
199 return 0;
200}
201
202const QCalendarLocale *QJalaliCalendar::localeMonthIndexData() const
203{
204 return locale_data;
205}
206
207const char16_t *QJalaliCalendar::localeMonthData() const
208{
209 return months_data;
210}
211
212QT_END_NAMESPACE
213