}
      return result;
    }

    @Override
    public long distance(Long start, Long end) {
      long result = end - start;
      if (end > start && result < 0) { // overflow
        return Long.MAX_VALUE;
      }
      if (end < start && result > 0) { // underflow
        return Long.MIN_VALUE;
      }
      return result;
    }

    @Override

    return result;
  }

  /*
   * For discussion of the safety of the following methods for operating on predecessors and
   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
   * link(), which is defined at the end of this file.
   */

  private int getPredecessor(int entry) {
    return ((int) (link(entry) >>> 32)) - 1;
  }

  @Override
  int getSuccessor(int entry) {

  private static String badPositionIndexes(int start, int end, int size) {
    if (start < 0 || start > size) {
      return badPositionIndex(start, size, "start index");
    }
    if (end < 0 || end > size) {
      return badPositionIndex(end, size, "end index");
    }
    // end < start
    return lenientFormat("end index (%s) must not be less than start index (%s)", end, start);
  }

  private Comparators() {}

  /**
   * Returns a new comparator which sorts iterables by comparing corresponding elements pairwise
   * until a nonzero result is found; imposes "dictionary order." If the end of one iterable is
   * reached, but not the other, the shorter iterable is considered to be less than the longer one.
   * For example, a lexicographical natural ordering over integers considers {@code [] < [1] < [1,

    @ParametricNullness private final K key;
    @VisibleForTesting @Nullable ValueEntry<K, V>[] hashTable;
    private int size = 0;
    private int modCount = 0;

    // We use the set object itself as the end of the linked list, avoiding an unnecessary
    // entry object per key.
    private ValueSetLink<K, V> firstEntry;
    private ValueSetLink<K, V> lastEntry;

    ValueSet(@ParametricNullness K key, int expectedValues) {

    // * Everything with (to <= index < from) should be removed.
    // * The element with (index == from) should be kept.
    // * Everything with (index > from) has not been checked yet.

    // Check from the end of the list backwards (minimize expected cost of
    // moving elements when remove() is called). Stop before 'from' because
    // we already know that should be kept.
    for (int n = list.size() - 1; n > from; n--) {

      if (!executed) {
        runnables = new RunnableExecutorPair(runnable, executor, runnables);
        return;
      }
    }
    // Execute the runnable immediately. Because of scheduling this may end up getting called before
    // some of the previously added runnables, but we're OK with that. If we want to change the
    // contract to guarantee ordering among runnables we'd have to modify the logic here to allow
    // it.

    mmHeap.addAll(Lists.newArrayList(1, 2));
    Iterator<Integer> it = mmHeap.iterator();
    assertTrue("Iterator has reached end prematurely", it.hasNext());
    it.next();
    it.next();
    try {
      it.next();
      fail("No exception thrown when iterating past end of heap");
    } catch (NoSuchElementException expected) {
    }
  }

  public void testIteratorConcurrentModification() {

    assertEquals("3", iterator.next());
    assertEquals("4", iterator.next());
    assertEquals(4, iterator.nextIndex());
    try {
      iterator.next();
      fail("did not detect end of list");
    } catch (NoSuchElementException expected) {
    }
    assertEquals(3, iterator.previousIndex());
    assertEquals("4", iterator.previous());
    assertEquals("3", iterator.previous());

      // multiple of 8. A multiple of 8 has 3 low zero bits, so we just need to figure out how many
      // extra zero bits we need to add to the end of bitsPerChar to get 3 in total.
      // The logic here would be wrong for bitsPerChar > 8, but since we require distinct ASCII
      // characters that can't happen.