private final int[] cellColumnInRowIndices;

  SparseImmutableTable(
      ImmutableList<Cell<R, C, V>> cellList,
      ImmutableSet<R> rowSpace,
      ImmutableSet<C> columnSpace) {
    Map<R, Integer> rowIndex = Maps.indexMap(rowSpace);
    Map<R, Map<C, V>> rows = new LinkedHashMap<>();
    for (R row : rowSpace) {
      rows.put(row, new LinkedHashMap<C, V>());
    }
    Map<C, Map<R, V>> columns = new LinkedHashMap<>();

@GwtCompatible
final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
  final ImmutableMap<T, Integer> rankMap;

  ExplicitOrdering(List<T> valuesInOrder) {
    this(Maps.indexMap(valuesInOrder));
  }

  ExplicitOrdering(ImmutableMap<T, Integer> rankMap) {
    this.rankMap = rankMap;
  }

  @Override
  public int compare(T left, T right) {

     * elements but rowKeySet() will be empty and containsRow() won't
     * acknowledge them.
     */
    rowKeyToIndex = Maps.indexMap(rowList);
    columnKeyToIndex = Maps.indexMap(columnList);

    @SuppressWarnings("unchecked")
    @Nullable V[][] tmpArray = (@Nullable V[][]) new Object[rowList.size()][columnList.size()];
    array = tmpArray;

    PowerSet(Set<E> input) {
      checkArgument(
          input.size() <= 30, "Too many elements to create power set: %s > 30", input.size());
      this.inputSet = Maps.indexMap(input);
    }

    @Override
    public int size() {
      return 1 << inputSet.size();
    }

    @Override
    public boolean isEmpty() {
      return false;
    }