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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
namespace System.Globalization
{
/// <summary>
/// This class implements the Julian calendar. In 48 B.C. Julius Caesar
/// ordered a calendar reform, and this calendar is called Julian calendar.
/// It consisted of a solar year of twelve months and of 365 days with an
/// extra day every fourth year.
/// </summary>
/// <remarks>
/// Calendar support range:
/// Calendar Minimum Maximum
/// ========== ========== ==========
/// Gregorian 0001/01/01 9999/12/31
/// Julia 0001/01/03 9999/10/19
/// </remarks>
public class JulianCalendar : Calendar
{
public static readonly int JulianEra = 1;
private const int DatePartYear = 0;
private const int DatePartDayOfYear = 1;
private const int DatePartMonth = 2;
private const int DatePartDay = 3;
// Number of days in a non-leap year
private const int JulianDaysPerYear = 365;
// Number of days in 4 years
private const int JulianDaysPer4Years = JulianDaysPerYear * 4 + 1;
// Gregorian Calendar 9999/12/31 = Julian Calendar 9999/10/19
// keep it as variable field for serialization compat.
internal int MaxYear = 9999;
public override DateTime MinSupportedDateTime => DateTime.MinValue;
public override DateTime MaxSupportedDateTime => DateTime.MaxValue;
public override CalendarAlgorithmType AlgorithmType => CalendarAlgorithmType.SolarCalendar;
public JulianCalendar()
{
// There is no system setting of TwoDigitYear max, so set the value here.
_twoDigitYearMax = 2049;
}
internal override CalendarId ID => CalendarId.JULIAN;
internal static void CheckEraRange(int era)
{
if (era != CurrentEra && era != JulianEra)
{
throw new ArgumentOutOfRangeException(nameof(era), era, SR.ArgumentOutOfRange_InvalidEraValue);
}
}
internal void CheckYearEraRange(int year, int era)
{
CheckEraRange(era);
if (year <= 0 || year > MaxYear)
{
throw new ArgumentOutOfRangeException(
nameof(year),
year,
SR.Format(SR.ArgumentOutOfRange_Range, 1, MaxYear));
}
}
internal static void CheckMonthRange(int month)
{
if (month < 1 || month > 12)
{
ThrowHelper.ThrowArgumentOutOfRange_Month(month);
}
}
/// <summary>
/// Check for if the day value is valid.
/// </summary>
/// <remarks>
/// Before calling this method, call CheckYearEraRange()/CheckMonthRange() to make
/// sure year/month values are correct.
/// </remarks>
internal static void CheckDayRange(int year, int month, int day)
{
if (year == 1 && month == 1)
{
// The minimum supported Julia date is Julian 0001/01/03.
if (day < 3)
{
throw new ArgumentOutOfRangeException(null, SR.ArgumentOutOfRange_BadYearMonthDay);
}
}
bool isLeapYear = (year % 4) == 0;
ReadOnlySpan<int> days = isLeapYear ? GregorianCalendar.DaysToMonth366 : GregorianCalendar.DaysToMonth365;
int monthDays = days[month] - days[month - 1];
if (day < 1 || day > monthDays)
{
throw new ArgumentOutOfRangeException(
nameof(day),
day,
SR.Format(SR.ArgumentOutOfRange_Range, 1, monthDays));
}
}
/// <summary>
/// Returns a given date part of this DateTime. This method is used
/// to compute the year, day-of-year, month, or day part.
/// </summary>
internal static int GetDatePart(long ticks, int part)
{
// Gregorian 1/1/0001 is Julian 1/3/0001. Remember DateTime(0) is referred to Gregorian 1/1/0001.
// The following line convert Gregorian ticks to Julian ticks.
long julianTicks = ticks + TicksPerDay * 2;
// n = number of days since 1/1/0001
int n = (int)(julianTicks / TicksPerDay);
// y4 = number of whole 4-year periods within 100-year period
int y4 = n / JulianDaysPer4Years;
// n = day number within 4-year period
n -= y4 * JulianDaysPer4Years;
// y1 = number of whole years within 4-year period
int y1 = n / JulianDaysPerYear;
// Last year has an extra day, so decrement result if 4
if (y1 == 4) y1 = 3;
// If year was requested, compute and return it
if (part == DatePartYear)
{
return y4 * 4 + y1 + 1;
}
// n = day number within year
n -= y1 * JulianDaysPerYear;
// If day-of-year was requested, return it
if (part == DatePartDayOfYear)
{
return n + 1;
}
// Leap year calculation looks different from IsLeapYear since y1, y4,
// and y100 are relative to year 1, not year 0
bool leapYear = (y1 == 3);
ReadOnlySpan<int> days = leapYear ? GregorianCalendar.DaysToMonth366 : GregorianCalendar.DaysToMonth365;
// All months have less than 32 days, so n >> 5 is a good conservative
// estimate for the month
int m = (n >> 5) + 1;
// m = 1-based month number
while (n >= days[m])
{
m++;
}
// If month was requested, return it
if (part == DatePartMonth)
{
return m;
}
// Return 1-based day-of-month
return n - days[m - 1] + 1;
}
/// <summary>
/// Returns the tick count corresponding to the given year, month, and day.
/// </summary>
internal static long DateToTicks(int year, int month, int day)
{
ReadOnlySpan<int> days = (year % 4 == 0) ? GregorianCalendar.DaysToMonth366 : GregorianCalendar.DaysToMonth365;
int y = year - 1;
int n = y * 365 + y / 4 + days[month - 1] + day - 1;
// Gregorian 1/1/0001 is Julian 1/3/0001. n * TicksPerDay is the ticks in JulianCalendar.
// Therefore, we subtract two days in the following to convert the ticks in JulianCalendar
// to ticks in Gregorian calendar.
return (n - 2) * TicksPerDay;
}
public override DateTime AddMonths(DateTime time, int months)
{
if (months < -120000 || months > 120000)
{
throw new ArgumentOutOfRangeException(
nameof(months),
months,
SR.Format(SR.ArgumentOutOfRange_Range, -120000, 120000));
}
int y = GetDatePart(time.Ticks, DatePartYear);
int m = GetDatePart(time.Ticks, DatePartMonth);
int d = GetDatePart(time.Ticks, DatePartDay);
int i = m - 1 + months;
if (i >= 0)
{
m = i % 12 + 1;
y += i / 12;
}
else
{
m = 12 + (i + 1) % 12;
y += (i - 11) / 12;
}
ReadOnlySpan<int> daysArray = (y % 4 == 0 && (y % 100 != 0 || y % 400 == 0)) ? GregorianCalendar.DaysToMonth366 : GregorianCalendar.DaysToMonth365;
int days = daysArray[m] - daysArray[m - 1];
if (d > days)
{
d = days;
}
long ticks = DateToTicks(y, m, d) + time.Ticks % TicksPerDay;
CheckAddResult(ticks, MinSupportedDateTime, MaxSupportedDateTime);
return new DateTime(ticks);
}
public override DateTime AddYears(DateTime time, int years)
{
return AddMonths(time, years * 12);
}
public override int GetDayOfMonth(DateTime time)
{
return GetDatePart(time.Ticks, DatePartDay);
}
public override DayOfWeek GetDayOfWeek(DateTime time) => time.DayOfWeek;
public override int GetDayOfYear(DateTime time)
{
return GetDatePart(time.Ticks, DatePartDayOfYear);
}
public override int GetDaysInMonth(int year, int month, int era)
{
CheckYearEraRange(year, era);
CheckMonthRange(month);
ReadOnlySpan<int> days = (year % 4 == 0) ? GregorianCalendar.DaysToMonth366 : GregorianCalendar.DaysToMonth365;
return days[month] - days[month - 1];
}
public override int GetDaysInYear(int year, int era)
{
// Year/Era range is done in IsLeapYear().
return IsLeapYear(year, era) ? 366 : 365;
}
public override int GetEra(DateTime time) => JulianEra;
public override int GetMonth(DateTime time)
{
return GetDatePart(time.Ticks, DatePartMonth);
}
public override int[] Eras => new int[] { JulianEra };
public override int GetMonthsInYear(int year, int era)
{
CheckYearEraRange(year, era);
return 12;
}
public override int GetYear(DateTime time)
{
return GetDatePart(time.Ticks, DatePartYear);
}
public override bool IsLeapDay(int year, int month, int day, int era)
{
CheckMonthRange(month);
// Year/Era range check is done in IsLeapYear().
if (IsLeapYear(year, era))
{
CheckDayRange(year, month, day);
return month == 2 && day == 29;
}
CheckDayRange(year, month, day);
return false;
}
public override int GetLeapMonth(int year, int era)
{
CheckYearEraRange(year, era);
return 0;
}
public override bool IsLeapMonth(int year, int month, int era)
{
CheckYearEraRange(year, era);
CheckMonthRange(month);
return false;
}
public override bool IsLeapYear(int year, int era)
{
CheckYearEraRange(year, era);
return year % 4 == 0;
}
public override DateTime ToDateTime(int year, int month, int day, int hour, int minute, int second, int millisecond, int era)
{
CheckYearEraRange(year, era);
CheckMonthRange(month);
CheckDayRange(year, month, day);
if (millisecond < 0 || millisecond >= MillisPerSecond)
{
throw new ArgumentOutOfRangeException(
nameof(millisecond),
millisecond,
SR.Format(SR.ArgumentOutOfRange_Range, 0, MillisPerSecond - 1));
}
if (hour < 0 || hour >= 24 || minute < 0 || minute >= 60 || second < 0 || second >= 60)
{
throw new ArgumentOutOfRangeException(null, SR.ArgumentOutOfRange_BadHourMinuteSecond);
}
return new DateTime(DateToTicks(year, month, day) + (new TimeSpan(0, hour, minute, second, millisecond)).Ticks);
}
public override int TwoDigitYearMax
{
get => _twoDigitYearMax;
set
{
VerifyWritable();
if (value < 99 || value > MaxYear)
{
throw new ArgumentOutOfRangeException(
nameof(value),
value,
SR.Format(SR.ArgumentOutOfRange_Range, 99, MaxYear));
}
_twoDigitYearMax = value;
}
}
public override int ToFourDigitYear(int year)
{
ArgumentOutOfRangeException.ThrowIfNegative(year);
if (year > MaxYear)
{
throw new ArgumentOutOfRangeException(
nameof(year),
year,
SR.Format(SR.ArgumentOutOfRange_Bounds_Lower_Upper, 1, MaxYear));
}
return base.ToFourDigitYear(year);
}
}
}
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