combineRangeBounds function

ComparableFilter? combineRangeBounds(ComparableFilter a, ComparableFilter b)

If a and b are a lower-bound and an upper-bound range filter on the same field, combines them into a single BoundedRangeFilter for one bounded index scan. Returns null when they are not a complementary bound pair.

Implementation

ComparableFilter? combineRangeBounds(ComparableFilter a, ComparableFilter b) {
  if (a is! SortingAwareFilter || b is! SortingAwareFilter) return null;
  if (a.field != b.field) return null;

  SortingAwareFilter? lower, upper;
  for (var f in [a, b]) {
    if (f.boundType == RangeBoundType.lower) {
      lower = f;
    } else if (f.boundType == RangeBoundType.upper) {
      upper = f;
    }
  }

  if (lower != null && upper != null) {
    return BoundedRangeFilter(a.field, lower, upper);
  }
  return null;
}