}

  // A static mapping from an Enum type to its set of LockGraphNodes.
  private static final ConcurrentMap<
          Class<? extends Enum<?>>, Map<? extends Enum<?>, LockGraphNode>>
      lockGraphNodesPerType = new MapMaker().weakKeys().makeMap();

  /** Creates a {@code CycleDetectingLockFactory.WithExplicitOrdering<E>}. */
  public static <E extends Enum<E>> WithExplicitOrdering<E> newInstanceWithExplicitOrdering(

            ? EnumMultiset.create(AnEnum.class)
            : EnumMultiset.create(asList(elements));
      }
    };
  }

  private enum Color {
    BLUE,
    RED,
    YELLOW,
    GREEN,
    WHITE
  }

  private enum Gender {
    MALE,
    FEMALE
  }

  public void testClassCreate() {
    Multiset<Color> ms = EnumMultiset.create(Color.class);
    ms.add(Color.RED);

```

否则，`/users/{user_id}` 将匹配 `/users/me`，FastAPI 会**认为**正在接收值为 `"me"` 的 `user_id` 参数。

## 预设值

路径操作使用 Python 的 <abbr title="Enumeration">`Enum`</abbr> 类型接收预设的*路径参数*。

### 创建 `Enum` 类

导入 `Enum` 并创建继承自 `str` 和 `Enum` 的子类。

通过从 `str` 继承，API 文档就能把值的类型定义为**字符串**，并且能正确渲染。

然后，创建包含固定值的类属性，这些固定值是可用的有效值：

```Python hl_lines="1  6-9"
{!../../docs_src/path_params/tutorial005.py!}

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.hash;


/**
 * An enum that contains all of the known hash functions.
 *
 * @author Kurt Alfred Kluever
 */
enum HashFunctionEnum {
  ADLER32(Hashing.adler32()),
  CRC32(Hashing.crc32()),
  GOOD_FAST_HASH_32(Hashing.goodFastHash(32)),
  GOOD_FAST_HASH_64(Hashing.goodFastHash(64)),

### Bir `Enum` Sınıfı Oluşturalım

`Enum` sınıfını projemize dahil edip `str` ile `Enum` sınıflarını miras alan bir alt sınıf yaratalım.

@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
@ElementTypesAreNonnullByDefault
final class ImmutableEnumMap<K extends Enum<K>, V> extends IteratorBasedImmutableMap<K, V> {
  static <K extends Enum<K>, V> ImmutableMap<K, V> asImmutable(EnumMap<K, V> map) {
    switch (map.size()) {
      case 0:
        return ImmutableMap.of();
      case 1:

  }

  @IgnoreJRERequirement // see enclosing class (whose annotation Animal Sniffer ignores here...)
  private static final class EnumSetAccumulator<E extends Enum<E>> {
    @SuppressWarnings({"rawtypes", "unchecked"})
    static final Collector<Enum<?>, ?, ImmutableSet<? extends Enum<?>>> TO_IMMUTABLE_ENUM_SET =
        (Collector) toImmutableEnumSetGeneric();

    @CheckForNull private EnumSet<E> set;

    void add(E e) {

from collections import deque
from dataclasses import dataclass
from datetime import datetime, timezone
from decimal import Decimal
from enum import Enum
from pathlib import PurePath, PurePosixPath, PureWindowsPath
from typing import Optional

import pytest
from fastapi._compat import PYDANTIC_V2, Undefined
from fastapi.encoders import jsonable_encoder
from pydantic import BaseModel, Field, ValidationError

 * com.google.common.net.InternetDomainName}.</b>
 *
 * <p>Specifies the type of a top-level domain definition.
 *
 * @since 23.3
 */
@Beta
@GwtCompatible
public enum PublicSuffixType {

  /** Public suffix that is provided by a private company, e.g. "blogspot.com" */
  PRIVATE(':', ','),
  /** Public suffix that is backed by an ICANN-style domain name registry */
  REGISTRY('!', '?');

  private Class<? extends Enum> enumType;

  private String[] sampleData;

  @BeforeExperiment
  void setUp() throws ClassNotFoundException {
    Preconditions.checkArgument(hitRate >= 0 && hitRate <= 1, "hitRate must be in the range [0,1]");

    enumType =
        Class.forName(EnumsBenchmark.class.getCanonicalName() + "$" + enumSize + "Enum")
            .asSubclass(Enum.class);