modulo method

Implementation

IntervalDomain modulo(IntervalDomain other) {
  if (isBottom || other.isBottom) return bottomValue;

  // Modulo by interval containing zero is undefined
  if (other.containsValue(0)) {
    return topValue;
  }

  // If either is infinite, result is bounded by divisor
  if (min == null || max == null || other.min == null || other.max == null) {
    // Result of a % b is in range [0, |b|-1] for positive a
    // or [-(|b|-1), |b|-1] for possibly negative a
    final maxDivisor = other.max?.abs();
    if (maxDivisor == null) return topValue;

    if (min != null && min! >= 0) {
      // Non-negative dividend: result is in [0, |b|-1]
      return IntervalDomain(0, maxDivisor - 1);
    }
    // Possibly negative dividend: result spans negative to positive
    return IntervalDomain(-(maxDivisor - 1), maxDivisor - 1);
  }

  // All bounds are finite
  final maxDivisor = math.max(other.min!.abs(), other.max!.abs());
  if (min! >= 0) {
    // Non-negative dividend
    return IntervalDomain(0, math.min(max!, maxDivisor - 1));
  } else if (max! < 0) {
    // Strictly negative dividend
    return IntervalDomain(math.max(min!, -(maxDivisor - 1)), 0);
  } else {
    // Spans zero
    return IntervalDomain(
      math.max(min!, -(maxDivisor - 1)),
      math.min(max!, maxDivisor - 1),
    );
  }
}