/// <summary>
/// Subtract an interval of time from a DateTime.
/// </summary>
public static DateTime SubtractInterval(this DateTime dt, Time.IntervalType interval)
{
if (interval == Time.IntervalType.Day)
{
return(dt.AddDays(-1));
}
else if (interval == Time.IntervalType.Week)
{
return(dt.AddDays(-7));
}
else if (interval == Time.IntervalType.Month) // not reversible version of AddInterval
{
return(dt.AddMonths(-1));
}
else if (interval == Time.IntervalType.Quarter) // won't necessarily work for qtr end dates
{
return(dt.AddMonths(-3));
}
else if (interval == Time.IntervalType.Year)
{
return(dt.AddYears(-1));
}
else
{
return(dt);
}
}
/// <summary>
/// Add an interval of time (or some multiple thereof) to a DateTime.
/// </summary>
public static DateTime AddInterval(this DateTime dt, Time.IntervalType interval, int numberOfIntervals)
{
if (interval == Time.IntervalType.Day)
{
return(dt.AddDays(numberOfIntervals));
}
else if (interval == Time.IntervalType.Week)
{
return(dt.AddDays(7 * numberOfIntervals));
}
else if (interval == Time.IntervalType.Month)
{
return(dt.AddMonths(numberOfIntervals));
}
else if (interval == Time.IntervalType.Quarter) // won't necessarily work for qtr end dates
{
return(dt.AddMonths(3 * numberOfIntervals));
}
else if (interval == Time.IntervalType.Year)
{
return(dt.AddYears(numberOfIntervals));
}
else
{
return(dt);
}
}
/// <summary>
/// Maps a function to a timeline, starting on a given date.
/// </summary>
// TODO: Get rid of Time.IntervalType
public static Tnum TemporalMap(Func <Tnum, Tnum> fcn, Tdate startDate, Tnum intervalCount, Time.IntervalType intervalType)
{
return(fcn(Time.IntervalsSince(startDate, startDate.AddYears(intervalCount), intervalType)));
}
