private Builder mergeAll()

in accord-core/src/main/java/accord/utils/btree/BTree.java [1684:1751]
57 lines of code
16 McCabe index (conditional complexity)

        private Builder<V> mergeAll(int addCount)
        {
            Object[] a = values;
            int addOffset = count;

            int i = 0, j = addOffset;
            int curEnd = addOffset, addEnd = addOffset + addCount;

            // save time in cases where we already have a subset, by skipping dir
            while (i < curEnd && j < addEnd)
            {
                V ai = (V) a[i], aj = (V) a[j];
                // in some cases, such as Columns, we may have identity supersets, so perform a cheap object-identity check
                int c = ai == aj ? 0 : comparator.compare(ai, aj);
                if (c > 0)
                    break;
                else if (c == 0)
                {
                    if (quickResolver != null)
                        a[i] = quickResolver.resolve(ai, aj);
                    j++;
                }
                i++;
            }

            if (j == addEnd)
                return this; // already a superset of the new values

            // otherwise, copy the remaining existing values to the very end, freeing up space for merge result
            int newCount = i;
            System.arraycopy(a, i, a, addEnd, count - i);
            curEnd = addEnd + (count - i);
            i = addEnd;

            while (i < curEnd && j < addEnd)
            {
                V ai = (V) a[i];
                V aj = (V) a[j];
                // could avoid one comparison if we cared, but would make this ugly
                int c = comparator.compare(ai, aj);
                if (c == 0)
                {
                    Object newValue = quickResolver == null ? ai : quickResolver.resolve(ai, aj);
                    a[newCount++] = newValue;
                    i++;
                    j++;
                }
                else
                {
                    a[newCount++] = c < 0 ? a[i++] : a[j++];
                }
            }

            // exhausted one of the inputs; fill in remainder of the other
            if (i < curEnd)
            {
                System.arraycopy(a, i, a, newCount, curEnd - i);
                newCount += curEnd - i;
            }
            else if (j < addEnd)
            {
                if (j != newCount)
                    System.arraycopy(a, j, a, newCount, addEnd - j);
                newCount += addEnd - j;
            }
            count = newCount;
            return this;
        }