/// <summary>
/// If the specified value is of any integral type and can be cast losslessly to a
/// <c>ulong</c>, gets the value as a <c>ulong</c>.
/// <para>
/// If the value is of a signed integral type but can be converted to a <c>ulong</c> without
/// losing data (i.e., the value is nonnegative), this method gets the converted value.
/// </para>
/// <para>
/// The result is empty if the specified value is not of an integral type or has a negative value.
/// </para>
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static Opt <ulong> UnsignedIntegralValueOpt(this IConvertible value)
{
if (value is ulong)
{
return(Opt.Full((ulong)value));
}
// Returns empty option if the value is negative.
return(value.IntegralValueWidenedToLongOpt()
.WhereFix(lv => lv >= 0)
.SelectFix(lv => (ulong)lv));
}
/// <summary>
/// If the specified value is of any integral type and can be cast losslessly to a
/// <c>long</c>, gets the value as a <c>long</c>.
/// <para>
/// If the value is a <c>ulong</c> but can be converted to a <c>long</c> without losing
/// data, this method gets the converted value.
/// </para>
/// <para>
/// The result is empty if the specified value is not of an integral type or is of
/// <c>ulong</c> with a value that cannot be stored losslessly as a <c>long</c>.
/// </para>
/// </summary>
/// <param name="value"></param>
/// <returns></returns>
public static Opt <long> SignedIntegralValueOpt(this IConvertible value)
{
if (value is ulong)
{
long v = (long)value;
if (v < 0)
{
return(Opt.Empty <long>());
}
return(Opt.Full(v));
}
else
{
return(value.IntegralValueWidenedToLongOpt());
}
}