return delegateCollection().comparator();
  }

  // Override indexOf() and lastIndexOf() to be O(log N) instead of O(N).

  @GwtIncompatible // ImmutableSortedSet.indexOf
  // TODO(cpovirk): consider manual binary search under GWT to preserve O(log N) lookup
  @Override
  public int indexOf(@CheckForNull Object target) {
    int index = delegateCollection().indexOf(target);

    assertThat(Floats.indexOf(EMPTY, EMPTY)).isEqualTo(0);
    assertThat(Floats.indexOf(ARRAY234, EMPTY)).isEqualTo(0);
    assertThat(Floats.indexOf(EMPTY, ARRAY234)).isEqualTo(-1);
    assertThat(Floats.indexOf(ARRAY234, ARRAY1)).isEqualTo(-1);
    assertThat(Floats.indexOf(ARRAY1, ARRAY234)).isEqualTo(-1);
    assertThat(Floats.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Floats.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);

    array[getNumElements() / 2] = e0();
    collection = getSubjectGenerator().create(array);
    assertEquals(
        "indexOf(duplicate) should return index of first occurrence", 0, getList().indexOf(e0()));
  }

    array[getNumElements() / 2] = e0();
    collection = getSubjectGenerator().create(array);
    assertEquals(
        "indexOf(duplicate) should return index of first occurrence", 0, getList().indexOf(e0()));
  }

  }

  public void testIndexOf() {
    assertThat(Ints.indexOf(EMPTY, (int) 1)).isEqualTo(-1);
    assertThat(Ints.indexOf(ARRAY1, (int) 2)).isEqualTo(-1);
    assertThat(Ints.indexOf(ARRAY234, (int) 1)).isEqualTo(-1);
    assertThat(Ints.indexOf(new int[] {(int) -1}, (int) -1)).isEqualTo(0);
    assertThat(Ints.indexOf(ARRAY234, (int) 2)).isEqualTo(0);
    assertThat(Ints.indexOf(ARRAY234, (int) 3)).isEqualTo(1);

    assertThat(Chars.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Chars.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);
    assertThat(Chars.indexOf(ARRAY234, new char[] {(char) 2, (char) 3})).isEqualTo(0);
    assertThat(Chars.indexOf(ARRAY234, new char[] {(char) 3, (char) 4})).isEqualTo(1);
    assertThat(Chars.indexOf(ARRAY234, new char[] {(char) 3})).isEqualTo(1);

  public void testIndexOf() {
    assertThat(Shorts.indexOf(EMPTY, (short) 1)).isEqualTo(-1);
    assertThat(Shorts.indexOf(ARRAY1, (short) 2)).isEqualTo(-1);
    assertThat(Shorts.indexOf(ARRAY234, (short) 1)).isEqualTo(-1);
    assertThat(Shorts.indexOf(new short[] {(short) -1}, (short) -1)).isEqualTo(0);
    assertThat(Shorts.indexOf(ARRAY234, (short) 2)).isEqualTo(0);
    assertThat(Shorts.indexOf(ARRAY234, (short) 3)).isEqualTo(1);

        int block;
        int i = 0;
        int index = 0;
        while (i < length) {
            block = (ALPHABET.indexOf(string.charAt(i++)) & 0xff) << 18 |
                    (ALPHABET.indexOf(string.charAt(i++)) & 0xff) << 12 |
                    (ALPHABET.indexOf(string.charAt(i++)) & 0xff) << 6 |
                    (ALPHABET.indexOf(string.charAt(i++)) & 0xff);
            buffer[index++] = (byte) (block >>> 16);

    assertEquals(size - 1, copy.indexOf(list.get(size - 1)));
    assertEquals(size - 2, head.indexOf(list.get(size - 2)));
    assertEquals(size - 2, tail.indexOf(list.get(size - 1)));
    assertEquals(-1, head.indexOf(list.get(size - 1)));
    assertEquals(-1, tail.indexOf(list.get(0)));
  }

  @CollectionSize.Require(absent = {ZERO, ONE})
  public void testSubList_lastIndexOf() {
    List<E> list = getList();

    assertThat(Bytes.indexOf(ARRAY1, ARRAY1)).isEqualTo(0);
    assertThat(Bytes.indexOf(ARRAY234, ARRAY234)).isEqualTo(0);
    assertThat(Bytes.indexOf(ARRAY234, new byte[] {(byte) 2, (byte) 3})).isEqualTo(0);
    assertThat(Bytes.indexOf(ARRAY234, new byte[] {(byte) 3, (byte) 4})).isEqualTo(1);
    assertThat(Bytes.indexOf(ARRAY234, new byte[] {(byte) 3})).isEqualTo(1);