/// <summary>
/// Equivalent to <see cref="Instant.SafePlus"/>, but in the opposite direction.
/// </summary>
internal Instant SafeMinus(Offset offset)
{
int days = duration.FloorDays;
// If we can do the arithmetic safely, do so.
if (days > Instant.MinDays && days < Instant.MaxDays)
{
return(Minus(offset));
}
// Handle BeforeMinValue and BeforeMaxValue simply.
if (days < Instant.MinDays)
{
return(Instant.BeforeMinValue);
}
if (days > Instant.MaxDays)
{
return(Instant.AfterMaxValue);
}
// Okay, do the arithmetic as a Duration, then check the result for overflow, effectively.
var asDuration = duration.MinusSmallNanoseconds(offset.Nanoseconds);
if (asDuration.FloorDays < Instant.MinDays)
{
return(Instant.BeforeMinValue);
}
if (asDuration.FloorDays > Instant.MaxDays)
{
return(Instant.AfterMaxValue);
}
// And now we don't need any more checks.
return(Instant.FromTrustedDuration(asDuration));
}
/// <summary> /// Returns a new instant based on this local instant, as if we'd applied a zero offset. /// This is just a slight optimization over calling <c>localInstant.Minus(Offset.Zero)</c>. /// </summary> internal Instant MinusZeroOffset() => Instant.FromTrustedDuration(duration);