private int GetDaysInFirstWeek(int year, GregorianCalendarSystem calendar)
{
// Some of the first few days of the week year may be in the previous week year.
// However, the whole of the first week of the week year definitely occurs
// within the first 13 days of January.
return Enumerable.Range(1, 13)
.Count(day => new LocalDate(year, 1, day, calendar).WeekOfWeekYear == 1);
}
static GregorianCalendarSystem()
{
GregorianCache = new GregorianCalendarSystem[7];
for (int i = 0; i < 7; i++)
{
GregorianCache[i] = new GregorianCalendarSystem(GregorianName, i + 1, null);
}
IsoInstance = new GregorianCalendarSystem(IsoName, 4, AssembleIsoFields);
for (int year = FirstOptimizedYear; year <= LastOptimizedYear; year++)
{
for (int month = 1; month <= 12; month++)
{
int yearMonthIndex = (year - FirstOptimizedYear) * 12 + month;
MonthStartTicks[yearMonthIndex] = IsoInstance.GetYearMonthTicks(year, month);
MonthLengths[yearMonthIndex] = IsoInstance.GetDaysInMonth(year, month);
}
}
}