Deveel.Data.Index.IndexRangeSet.IntersectOn C# (CSharp) Method

        private static IndexRange IntersectOn(IndexRange range, SqlExpressionType op, Field value, bool nullCheck)
        {
            var start = range.StartValue;
            var startPosition = range.StartOffset;
            var end = range.EndValue;
            var endPosition = range.EndOffset;

            bool inclusive = op == SqlExpressionType.Is ||
                             op == SqlExpressionType.Equal ||
                             op == SqlExpressionType.GreaterOrEqualThan ||
                             op == SqlExpressionType.SmallerOrEqualThan;

            if (op == SqlExpressionType.Is ||
                op == SqlExpressionType.Equal ||
                op == SqlExpressionType.GreaterThan ||
                op == SqlExpressionType.GreaterOrEqualThan) {
                // With this operator, NULL values must return null.
                if (nullCheck && value.IsNull) {
                    return IndexRange.Null;
                }

                if (start.Equals(IndexRange.FirstInSet)) {
                    start = value;
                    startPosition = inclusive ? RangeFieldOffset.FirstValue : RangeFieldOffset.AfterLastValue;
                } else {
                    int c = value.CompareTo(start);
                    if ((c == 0 && startPosition == RangeFieldOffset.FirstValue) || c > 0) {
                        start = value;
                        startPosition = inclusive ? RangeFieldOffset.FirstValue : RangeFieldOffset.AfterLastValue;
                    }
                }
            }

            if (op == SqlExpressionType.Is ||
                op == SqlExpressionType.Equal ||
                op == SqlExpressionType.SmallerThan ||
                op == SqlExpressionType.SmallerOrEqualThan) {
                // With this operator, NULL values must return null.
                if (nullCheck && value.IsNull) {
                    return IndexRange.Null;
                }

                // If start is first in set, then we have to change it to after NULL
                if (nullCheck && start.Equals(IndexRange.FirstInSet)) {
                    start = Field.Null();
                    startPosition = RangeFieldOffset.AfterLastValue;
                }

                if (end.Equals(IndexRange.LastInSet)) {
                    end = value;
                    endPosition = inclusive ? RangeFieldOffset.LastValue : RangeFieldOffset.BeforeFirstValue;
                } else {
                    int c = value.CompareTo(end);
                    if ((c == 0 && endPosition == RangeFieldOffset.LastValue) || c < 0) {
                        end = value;
                        endPosition = inclusive ? RangeFieldOffset.LastValue : RangeFieldOffset.BeforeFirstValue;
                    }
                }
            }

            // If start and end are not null types (if either are, then it means it
            // is a placeholder value meaning start or end of set).
            if (!start.Equals(IndexRange.FirstInSet) &&
                !end.Equals(IndexRange.LastInSet)) {
                // If start is higher than end, return null
                int c = start.CompareTo(end);
                if ((c == 0 && (startPosition == RangeFieldOffset.AfterLastValue ||
                                endPosition == RangeFieldOffset.BeforeFirstValue)) ||
                    c > 0) {
                    return IndexRange.Null;
                }
            }

            // The new intersected range
            return new IndexRange(startPosition, start, endPosition, end);
        }