/// <summary>
/// Performs an "intersection" of the two sets, where only the elements
/// that are present in both sets remain. That is, the element is included only if it exists in
/// both <c>a</c> and <c>b</c>. Neither input object is modified by the operation.
/// The result object is a <c>Clone()</c> of one of the input objects (<c>a</c> if it is not <c>null</c>) containing the
/// elements from the intersect operation.
/// </summary>
/// <param name="a">A set of elements.</param>
/// <param name="b">A set of elements.</param>
/// <returns>The intersection of the two input sets. <c>null</c> if both sets are <c>null</c>.</returns>
public static Set Intersect(Set a, Set b)
{
if (a == null && b == null)
{
return(null);
}
else if (a == null)
{
Set resultSet = (Set)((Set)b).Clone();
resultSet.Clear();
return(resultSet);
}
else if (b == null)
{
Set resultSet = (Set)((Set)a).Clone();
resultSet.Clear();
return(resultSet);
}
else
{
return(a.Intersect(b));
}
}
