}

  public void testConcat_infiniteIterable() throws IOException {
    CharSource source = CharSource.wrap("abcd");
    Iterable<CharSource> cycle = Iterables.cycle(ImmutableList.of(source));
    CharSource concatenated = CharSource.concat(cycle);

    String expected = "abcdabcd";

    // read the first 8 chars manually, since there's no equivalent to ByteSource.slice

     * cycles; otherwise symlinks are traversed.
     *
     * @param directory the root of the directory to scan
     * @param packagePrefix resource path prefix inside {@code classloader} for any files found
     *     under {@code directory}
     * @param currentPath canonical files already visited in the current directory tree path, for
     *     cycle elimination
     */

   * ThreadLocal is usually implemented with a WeakReference, which can have negative performance
   * properties; for example, calling WeakReference.get() on Android will block during an
   * otherwise-concurrent GC cycle.
   */
  private static final class TaskNonReentrantExecutor extends AtomicReference<RunningState>
      implements Executor, Runnable {

    /**

    // "HashBiMap.hashTableKToV" and "BiEntry.nextInKToVBucket" references.
    // Under that assumption, the remaining references can be safely marked as @Weak.
    // Using @Weak is necessary to avoid retain-cycles between BiEntry instances on iOS,
    // which would cause memory leaks when non-empty HashBiMap with cyclic BiEntry
    // instances is deallocated.
    @CheckForNull BiEntry<K, V> nextInKToVBucket;

    //     (All indices taken mod n.) If d and n are mutually prime, all elements will have been
    //     moved at that point. Otherwise, we can rotate the cycle a[1], a[1 + d], a[1 + 2d], etc,
    //     then a[2] etc, and so on until we have rotated all elements. There are gcd(d, n) cycles
    //     in all.
    // (3) "Successive". We can consider that we are exchanging a block of size d (a[0..d-1]) with a

  }

  public void testSetIndirectSelf_toString() {
    final SettableFuture<Object> orig = SettableFuture.create();
    // unlike the above this indirection defeats the trivial cycle detection and causes a SOE
    orig.setFuture(
        new ForwardingListenableFuture<Object>() {
          @Override
          protected ListenableFuture<Object> delegate() {
            return orig;
          }

   *       number of nodes that have been seen but not yet visited, that is, the "horizon").
   * </ul>
   *
   * @param graph {@link SuccessorsFunction} representing a general graph that may have cycles.
   */
  public static <N> Traverser<N> forGraph(SuccessorsFunction<N> graph) {
    return new Traverser<N>(graph) {
      @Override
      Traversal<N> newTraversal() {
        return Traversal.inGraph(graph);

   * should use an explicit {@code break} or be certain that you will eventually remove all the
   * elements.
   */
  @SafeVarargs
  public static <T extends @Nullable Object> Iterator<T> cycle(T... elements) {
    return cycle(Lists.newArrayList(elements));
  }

  /**
   * Returns an Iterator that walks the specified array, nulling out elements behind it. This can

  private void appendUserObject(StringBuilder builder, @CheckForNull Object o) {
    // This is some basic recursion detection for when people create cycles via set/setFuture or
    // when deep chains of futures exist resulting in a StackOverflowException. We could detect
    // arbitrary cycles using a thread local but this should be a good enough solution (it is also
    // what jdk collections do in these cases)
    try {

   * use {@code Stream.generate(() -> collection).flatMap(Collection::stream)}.
   */
  public final FluentIterable<E> cycle() {
    return from(Iterables.cycle(getDelegate()));
  }

  /**
   * Returns a fluent iterable whose iterators traverse first the elements of this fluent iterable,