columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
    }
    this.columnMap = columnBuilder.buildOrThrow();
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    // Casts without copying.
    return ImmutableMap.copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.

  }

  @LazyInit private transient @Nullable ColumnMap columnMap;

  @Override
  public Map<C, Map<R, @Nullable V>> columnMap() {
    ColumnMap map = columnMap;
    return (map == null) ? columnMap = new ColumnMap() : map;
  }

  @WeakOuter
  private final class ColumnMap extends ArrayMap<C, Map<R, @Nullable V>> {
    private ColumnMap() {
      super(columnKeyToIndex);
    }

    @Override

      cellColumnIndices[i] = columnIndex;
    }
    this.cellRowIndices = cellRowIndices;
    this.cellColumnIndices = cellColumnIndices;
    this.rowMap = new RowMap();
    this.columnMap = new ColumnMap();
  }

  /** An immutable map implementation backed by an indexed nullable array. */
  private abstract static class ImmutableArrayMap<K, V> extends IteratorBasedImmutableMap<K, V> {
    private final int size;

      return Maps.transformValues(fromTable.rowMap(), row -> Maps.transformValues(row, function));
    }

    @Override
    public Map<C, Map<R, V2>> columnMap() {
      return Maps.transformValues(
          fromTable.columnMap(), column -> Maps.transformValues(column, function));
    }
  }

  /**
   * Returns an unmodifiable view of the specified table. This method allows modules to provide

      columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
    }
    this.columnMap = columnBuilder.buildOrThrow();
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    // Casts without copying.
    return ImmutableMap.copyOf(columnMap);
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {
    // Casts without copying.

  }

  @Override
  public boolean containsColumn(@Nullable Object columnKey) {
    return Maps.safeContainsKey(columnMap(), columnKey);
  }

  @Override
  public Set<R> rowKeySet() {
    return rowMap().keySet();
  }

  @Override
  public Set<C> columnKeySet() {
    return columnMap().keySet();
  }

  @Override
  public boolean containsValue(@Nullable Object value) {

  }

  public void testColumnKeySet() {
    assertEquals(ImmutableSet.of(), INSTANCE.columnKeySet());
  }

  public void testColumnMap() {
    assertEquals(ImmutableMap.of(), INSTANCE.columnMap());
  }

  public void testContains() {
    assertFalse(INSTANCE.contains('a', 1));
  }

  public void testContainsColumn() {
    assertFalse(INSTANCE.containsColumn(1));
  }

    checkNotNull(columnKey);
    return containsColumn(columnKey)
        ? ImmutableMap.of(singleRowKey, singleValue)
        : ImmutableMap.of();
  }

  @Override
  public ImmutableMap<C, Map<R, V>> columnMap() {
    return ImmutableMap.of(singleColumnKey, (Map<R, V>) ImmutableMap.of(singleRowKey, singleValue));
  }

  @Override
  public ImmutableMap<R, Map<C, V>> rowMap() {

  public ImmutableMap<R, V> column(C columnKey) {
    checkNotNull(columnKey, "columnKey");
    return MoreObjects.firstNonNull(
        (ImmutableMap<R, V>) columnMap().get(columnKey), ImmutableMap.of());
  }

  @Override
  public ImmutableSet<C> columnKeySet() {
    return columnMap().keySet();
  }

  /**
   * {@inheritDoc}
   *

  public ImmutableMap<R, V> column(C columnKey) {
    checkNotNull(columnKey, "columnKey");
    return MoreObjects.firstNonNull(
        (ImmutableMap<R, V>) columnMap().get(columnKey), ImmutableMap.of());
  }

  @Override
  public ImmutableSet<C> columnKeySet() {
    return columnMap().keySet();
  }

  /**
   * {@inheritDoc}
   *