MapMaker builder) {
    if (builder.getKeyStrength() == Strength.STRONG
        && builder.getValueStrength() == Strength.STRONG) {
      return new MapMakerInternalMap<>(builder, StrongKeyStrongValueEntry.Helper.<K, V>instance());
    }
    if (builder.getKeyStrength() == Strength.STRONG
        && builder.getValueStrength() == Strength.WEAK) {

        }
      };

  private CacheBuilderFactory factoryWithAllKeyStrengths() {
    return new CacheBuilderFactory()
        .withKeyStrengths(ImmutableSet.of(STRONG, Strength.WEAK))
        .withValueStrengths(ImmutableSet.of(STRONG, Strength.WEAK, Strength.SOFT));
  }

  private Iterable<LoadingCache<Key, String>> caches() {
    CacheBuilderFactory factory = factoryWithAllKeyStrengths();
    return Iterables.transform(

    assertEquals(20, spec.maximumSize.intValue());
    assertNull(spec.maximumWeight);
    assertEquals(30, spec.concurrencyLevel.intValue());
    assertEquals(Strength.WEAK, spec.keyStrength);
    assertEquals(Strength.WEAK, spec.valueStrength);
    assertEquals(HOURS, spec.writeExpirationTimeUnit);
    assertEquals(MINUTES, spec.accessExpirationTimeUnit);
    assertEquals(1L, spec.writeExpirationDuration);

   * @throws IllegalStateException if the key strength was already set
   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);

    assertEquals(20, spec.maximumSize.intValue());
    assertNull(spec.maximumWeight);
    assertEquals(30, spec.concurrencyLevel.intValue());
    assertEquals(Strength.WEAK, spec.keyStrength);
    assertEquals(Strength.WEAK, spec.valueStrength);
    assertEquals(HOURS, spec.writeExpirationTimeUnit);
    assertEquals(MINUTES, spec.accessExpirationTimeUnit);
    assertEquals(1L, spec.writeExpirationDuration);

      MapMaker builder) {
    if (builder.getKeyStrength() == Strength.STRONG
        && builder.getValueStrength() == Strength.STRONG) {
      return new MapMakerInternalMap<>(builder, StrongKeyStrongValueEntry.Helper.<K, V>instance());
    }
    if (builder.getKeyStrength() == Strength.STRONG
        && builder.getValueStrength() == Strength.WEAK) {

   * @throws IllegalStateException if the key strength was already set
   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);

    checkStrength(map, Strength.WEAK, Strength.STRONG);
    assertSame(EntryFactory.WEAK, map.entryFactory);
  }

  public void testSetWeakValues() {
    LocalCache<Object, Object> map = makeLocalCache(createCacheBuilder().weakValues());
    checkStrength(map, Strength.STRONG, Strength.WEAK);
    assertSame(EntryFactory.STRONG, map.entryFactory);
  }

    checkStrength(map, Strength.WEAK, Strength.STRONG);
    assertSame(EntryFactory.WEAK, map.entryFactory);
  }

  public void testSetWeakValues() {
    LocalCache<Object, Object> map = makeLocalCache(createCacheBuilder().weakValues());
    checkStrength(map, Strength.STRONG, Strength.WEAK);
    assertSame(EntryFactory.STRONG, map.entryFactory);
  }

  boolean usesAccessEntries() {
    return usesAccessQueue() || recordsAccess();
  }

  boolean usesKeyReferences() {
    return keyStrength != Strength.STRONG;
  }

  boolean usesValueReferences() {
    return valueStrength != Strength.STRONG;
  }

  enum Strength {
    /*
     * TODO(kevinb): If we strongly reference the value and aren't loading, we needn't wrap the
     * value. This could save ~8 bytes per entry.