*/

package com.google.common.collect;

import java.util.Set;

/**
 * GWT emulation of {@link ImmutableEnumSet}. The type parameter is not bounded by {@code Enum<E>}
 * to avoid code-size bloat.
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
final class ImmutableEnumSet<E> extends ForwardingImmutableSet<E> {
  static <E> ImmutableSet<E> asImmutable(Set<E> delegate) {
    switch (delegate.size()) {

    Set<SomeEnum> units = Sets.immutableEnumSet(SomeEnum.D, SomeEnum.B);

    assertThat(units).containsExactly(SomeEnum.B, SomeEnum.D).inOrder();

    Set<SomeEnum> copy = SerializableTester.reserializeAndAssert(units);
    assertTrue(copy instanceof ImmutableEnumSet);
  }

  public void testImmutableEnumSet_fromIterable() {
    ImmutableSet<SomeEnum> none = Sets.immutableEnumSet(MinimalIterable.<SomeEnum>of());

  public static <E extends Enum<E>> ImmutableSet<E> immutableEnumSet(Iterable<E> elements) {
    if (elements instanceof ImmutableEnumSet) {
      return (ImmutableEnumSet<E>) elements;
    } else if (elements instanceof Collection) {
      Collection<E> collection = (Collection<E>) elements;
      if (collection.isEmpty()) {
        return ImmutableSet.of();
      } else {
        return ImmutableEnumSet.asImmutable(EnumSet.copyOf(collection));

        return this;
      }
    }

    ImmutableSet<E> toImmutableSet() {
      if (set == null) {
        return ImmutableSet.of();
      }
      ImmutableSet<E> ret = ImmutableEnumSet.asImmutable(set);
      set = null; // subsequent manual manipulation of the accumulator mustn't affect ret
      return ret;
    }
  }

  @GwtIncompatible
  @SuppressWarnings({"rawtypes", "unchecked"})