private static int numDaysInMon(int year, int mon)
{
if (DateTime.isLeapYear(year))
{
return(DateTime.daysInMonLeap[mon]);
}
else
{
return(DateTime.daysInMon[mon]);
}
}
public Duration minusDate(Date that)
{
// short circuit if equal
if (this.Equals(that))
{
return(Duration.Zero);
}
// compute so that a < b
Date a = this;
Date b = that;
if (a.compare(b) > 0)
{
b = this; a = that;
}
// compute difference in days
long days = 0;
if (a.m_year == b.m_year)
{
days = b.dayOfYear() - a.dayOfYear();
}
else
{
days = (DateTime.isLeapYear(a.m_year) ? 366 : 365) - a.dayOfYear();
days += b.dayOfYear();
for (int i = a.m_year + 1; i < b.m_year; ++i)
{
days += DateTime.isLeapYear(i) ? 366 : 365;
}
}
// negate if necessary if a was this
if (a == this)
{
days = -days;
}
// map days into ns ticks
return(Duration.make(days * Duration.nsPerDay));
}
