@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public final class Iterables {
  private Iterables() {}

  /** Returns an unmodifiable view of {@code iterable}. */
  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
      final Iterable<? extends T> iterable) {
    checkNotNull(iterable);
    if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {

   * this method returns {@code true} if {@code iterable1} and {@code iterable2} contain the same
   * number of elements and every element of {@code iterable1} is equal to the corresponding element
   * of {@code iterable2}.
   */
  public static boolean elementsEqual(Iterable<?> iterable1, Iterable<?> iterable2) {
    if (iterable1 instanceof Collection && iterable2 instanceof Collection) {

    assertEqualCharNodes(result, "bfaecd");
  }

  @Test
  public void forGraph_breadthFirst_infinite() {
    Iterable<Integer> result =
        Traverser.forGraph(fixedSuccessors(Iterables.cycle(1, 2, 3))).breadthFirst(0);
    assertThat(Iterables.limit(result, 4)).containsExactly(0, 1, 2, 3).inOrder();
  }

  @Test
  public void forGraph_breadthFirst_diamond() {

    }
  }

  private void testGetOnAbc(Iterable<String> iterable) {
    try {
      Iterables.get(iterable, -1);
      fail();
    } catch (IndexOutOfBoundsException expected) {
    }
    assertEquals("a", Iterables.get(iterable, 0));
    assertEquals("b", Iterables.get(iterable, 1));
    assertEquals("c", Iterables.get(iterable, 2));
    try {
      Iterables.get(iterable, 3);
      fail();

    }
  }

  private void testGetOnAbc(Iterable<String> iterable) {
    try {
      Iterables.get(iterable, -1);
      fail();
    } catch (IndexOutOfBoundsException expected) {
    }
    assertEquals("a", Iterables.get(iterable, 0));
    assertEquals("b", Iterables.get(iterable, 1));
    assertEquals("c", Iterables.get(iterable, 2));
    try {
      Iterables.get(iterable, 3);
      fail();

  @Benchmark
  void charSplitter(int reps) {
    int total = 0;

    for (int i = 0; i < reps; i++) {
      total += Iterables.size(CHAR_SPLITTER.split(input));
    }
  }

  @Benchmark
  void stringSplitter(int reps) {
    int total = 0;

    for (int i = 0; i < reps; i++) {
      total += Iterables.size(STRING_SPLITTER.split(input));
    }
  }

  @Benchmark
  void charSplitter(int reps) {
    int total = 0;

    for (int i = 0; i < reps; i++) {
      total += Iterables.size(CHAR_SPLITTER.split(input));
    }
  }

  @Benchmark
  void stringSplitter(int reps) {
    int total = 0;

    for (int i = 0; i < reps; i++) {
      total += Iterables.size(STRING_SPLITTER.split(input));
    }
  }

  static final Iterable<Double> INFINITIES =
      Doubles.asList(Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY);
  static final Iterable<Double> FINITE_DOUBLE_CANDIDATES;
  static final Iterable<Double> POSITIVE_FINITE_DOUBLE_CANDIDATES;
  static final Iterable<Double> ALL_DOUBLE_CANDIDATES;
  static final Iterable<Double> DOUBLE_CANDIDATES_EXCEPT_NAN;

  static {

  static final Iterable<Double> INFINITIES =
      Doubles.asList(Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY);
  static final Iterable<Double> FINITE_DOUBLE_CANDIDATES;
  static final Iterable<Double> POSITIVE_FINITE_DOUBLE_CANDIDATES;
  static final Iterable<Double> ALL_DOUBLE_CANDIDATES;
  static final Iterable<Double> DOUBLE_CANDIDATES_EXCEPT_NAN;

  static {

   *     original iterable.
   * @throws NullPointerException if the specified iterable is null or has any null elements.
   * @since 12.0
   */
  public static <E extends Comparable<? super E>> Collection<List<E>> orderedPermutations(
      Iterable<E> elements) {
    return orderedPermutations(elements, Ordering.natural());
  }

  /**
   * Returns a {@link Collection} of all the permutations of the specified {@link Iterable} using