示例#1
0
        /// <summary>
        /// Finds members of a bitset that are not in the other set (ANDNOT).
        /// This does not modify either bitset.
        /// </summary>
        /// <param name="otherSet">The set to compare against</param>
        /// <returns>A new IBitset containing the members that are in
        /// the first bitset but not in the second.</returns>
        public IBitset andNot(RoaringBitset otherSet)
        {
            RoaringBitset answer = new RoaringBitset();
            int           pos1 = 0, pos2 = 0;
            int           length1 = containers.size, length2 = otherSet.containers.size;

            while (pos1 < length1 && pos2 < length2)
            {
                ushort s1 = containers.getKeyAtIndex(pos1);
                ushort s2 = otherSet.containers.getKeyAtIndex(pos2);
                if (s1 == s2)
                {
                    Container c1 = containers.getContainerAtIndex(pos1);
                    Container c2 = otherSet.containers.getContainerAtIndex(pos2);
                    Container c  = c1.andNot(c2);
                    if (c.getCardinality() > 0)
                    {
                        answer.containers.append(s1, c);
                    }
                    ++pos1;
                    ++pos2;
                }
                else if (Utility.compareUnsigned(s1, s2) < 0)
                { // s1 < s2
                    int nextPos1 = containers.advanceUntil(s2, pos1);
                    answer.containers.appendCopy(containers, pos1, nextPos1);
                    pos1 = nextPos1;
                }
                else
                { // s1 > s2
                    pos2 = otherSet.containers.advanceUntil(s1, pos2);
                }
            }
            if (pos2 == length2)
            {
                answer.containers.appendCopy(containers, pos1, length1);
            }
            return(answer);
        }