/// <summary>
/// Returns the intersection between the given interval and this interval.
/// </summary>
/// <param name="interval">
/// The specified interval to intersect with this one.
/// </param>
/// <returns>
/// A <see cref="DateInterval"/> corresponding to the intersection between the given interval and the current
/// instance. If there is no intersection, a null reference is returned.
/// </returns>
/// <exception cref="ArgumentException"><paramref name="interval" /> uses a different
/// calendar to this date interval.</exception>
public DateInterval?Intersection(DateInterval interval) =>
Contains(interval) ? interval
: interval.Contains(this) ? this
: interval.Contains(Start) ? new DateInterval(Start, interval.End)
: interval.Contains(End) ? new DateInterval(interval.Start, End)
: null;
private void ValidateInterval(DateInterval interval)
{
Preconditions.CheckNotNull(interval, nameof(interval));
Preconditions.CheckArgument(interval.Calendar.Equals(Start.Calendar), nameof(interval),
"The specified interval uses a different calendar system to this one");
}
/// <summary>
/// Checks whether the given interval is within this interval. This requires that the start date of the specified
/// interval is not earlier than the start date of this interval, and the end date of the specified interval is not
/// later than the end date of this interval.
/// </summary>
/// <remarks>
/// An interval contains another interval with same start and end dates, or itself.
/// </remarks>
/// <param name="interval">The interval to check for containment within this interval.</param>
/// <exception cref="ArgumentException"><paramref name="interval" /> uses a different
/// calendar to this date interval.</exception>
/// <returns><c>true</c> if <paramref name="interval"/> is within this interval; <c>false</c> otherwise.</returns>
public bool Contains(DateInterval interval)
{
ValidateInterval(interval);
return(Start <= interval.Start && interval.End <= End);
}