/// <summary>
/// Can be only called if num is in type's set of numbers, e. g.
/// we can upcast longeger to real, but we cannot upcast complex to real
/// </summary>
/// <param name="num">
/// Number to upcast
/// </param>
/// <param name="type">
/// The level the Number to upcast to
/// </param>
/// <returns></returns>
internal static Number UpCastTo(Number num, Number.HierarchyLevel type)
{
if (num.Type == type)
{
return(num);
}
if (!num.Is(type))
{
throw new InvalidNumberCastException(num.Type, type);
}
return(Number.SuperSwitch(
num => new IntegerNumber(num[0] as Number),
num => new RationalNumber(num[0]),
num => new RealNumber(num[0] as Number),
num => new ComplexNumber(num[0]),
type,
num
));
}