import org.jspecify.annotations.Nullable;

/** An ordering that treats {@code null} as less than all other values. */
@GwtCompatible
final class NullsFirstOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
    implements Serializable {
  final Ordering<? super T> ordering;

  NullsFirstOrdering(Ordering<? super T> ordering) {
    this.ordering = ordering;
  }

  @Override

        .addEqualityGroup(Ordering.natural())
        .testEquals();
  }

  public void testIsInOrder() {
    assertFalse(isInOrder(asList(5, 3, 0, 9), Ordering.natural()));
    assertFalse(isInOrder(asList(0, 5, 3, 9), Ordering.natural()));
    assertTrue(isInOrder(asList(0, 3, 5, 9), Ordering.natural()));
    assertTrue(isInOrder(asList(0, 0, 3, 3), Ordering.natural()));

import org.jspecify.annotations.Nullable;

/**
 * An ordering that orders elements by applying an order to the result of a function on those
 * elements.
 */
@GwtCompatible
final class ByFunctionOrdering<F extends @Nullable Object, T extends @Nullable Object>
    extends Ordering<F> implements Serializable {
  final Function<F, ? extends T> function;
  final Ordering<T> ordering;

    Ordering<@Nullable Comparable<?>> result = nullsLast;
    if (result == null) {
      result = nullsLast = super.<Comparable<?>>nullsLast();
    }
    return (Ordering<@Nullable S>) result;
  }

  @Override
  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??
  public <S extends Comparable<?>> Ordering<S> reverse() {

 * according to the key comparator ordering or the natural ordering of the keys. Similarly, {@code
 * get}, {@code removeAll}, and {@code replaceValues} return collections that iterate through the
 * values according to the value comparator ordering or the natural ordering of the values. The
 * collections generated by {@code entries}, {@code keys}, and {@code values} iterate across the

        .addEqualityGroup(Ordering.natural())
        .testEquals();
  }

  public void testIsInOrder() {
    assertFalse(isInOrder(asList(5, 3, 0, 9), Ordering.natural()));
    assertFalse(isInOrder(asList(0, 5, 3, 9), Ordering.natural()));
    assertTrue(isInOrder(asList(0, 3, 5, 9), Ordering.natural()));
    assertTrue(isInOrder(asList(0, 0, 3, 3), Ordering.natural()));

    assertEquals(tree, copyFromTree);
    assertThat(copyFromTree.keyComparator()).isEqualTo(Ordering.natural());
    assertThat(copyFromTree.valueComparator()).isEqualTo(Ordering.natural());
    assertThat(copyFromTree.get(1.0).comparator()).isEqualTo(Ordering.natural());
  }

  /** Test that creating one TreeMultimap from a non-TreeMultimap results in natural ordering. */
  public void testCreateFromHashMultimap() {

  /**
   * The type of ordering that this object specifies.
   *
   * <ul>
   *   <li>UNORDERED: no order is guaranteed.
   *   <li>STABLE: ordering is guaranteed to follow a pattern that won't change between releases.
   *       Some methods may have stronger guarantees.
   *   <li>INSERTION: insertion ordering is guaranteed.
   *   <li>SORTED: ordering according to a supplied comparator is guaranteed.
   * </ul>

      GeneralRange<@Nullable Integer> range = GeneralRange.downTo(ORDERING, 3, lBoundType);
      for (Integer i : IN_ORDER_VALUES) {
        assertEquals(
            ORDERING.compare(i, 3) > 0 || (ORDERING.compare(i, 3) == 0 && lBoundType == CLOSED),
            range.contains(i));
        assertEquals(
            ORDERING.compare(i, 3) < 0 || (ORDERING.compare(i, 3) == 0 && lBoundType == OPEN),
            range.tooLow(i));

    return copyOfInternal((Ordering<E>) Ordering.natural(), (Collection<E>) elements, false);
  }

  // Unsafe, see ImmutableSortedSetFauxverideShim.
  @SuppressWarnings("unchecked")
  public static <E> ImmutableSortedSet<E> copyOf(Iterable<? extends E> elements) {
    return copyOfInternal((Ordering<E>) Ordering.natural(), (Iterable<E>) elements, false);
  }