1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.maven.di;
20
21 import java.util.function.Supplier;
22
23 import org.apache.maven.api.annotations.Experimental;
24 import org.apache.maven.api.annotations.Nonnull;
25
26 /**
27 * Defines how object instances are managed within a specific scope.
28 * <p>
29 * A Scope controls the lifecycle and visibility of objects created by the injector.
30 * It determines when new instances are created and when existing instances can be
31 * reused. This allows for different caching strategies depending on the desired
32 * lifecycle of the objects.
33 * <p>
34 * Example implementation for a simple caching scope:
35 * <pre>
36 * public class CachingScope implements Scope {
37 * private final Map<Key<?>, Object> cache = new ConcurrentHashMap<>();
38 *
39 * {@literal @}Override
40 * public <T> Supplier<T> scope(Key<T> key, Supplier<T> unscoped) {
41 * return () -> {
42 * return (T) cache.computeIfAbsent(key, k -> unscoped.get());
43 * };
44 * }
45 * }
46 * </pre>
47 *
48 * @see org.apache.maven.api.di.Scope
49 * @since 4.0.0
50 */
51 @Experimental
52 public interface Scope {
53
54 /**
55 * Scopes a supplier of instances.
56 * <p>
57 * This method wraps an unscoped instance supplier with scope-specific logic
58 * that controls when new instances are created versus when existing instances
59 * are reused.
60 *
61 * @param <T> the type of instance being scoped
62 * @param key the key identifying the instance type
63 * @param unscoped the original unscoped instance supplier
64 * @return a scoped supplier that implements the scope's caching strategy
65 * @throws NullPointerException if key or unscoped is null
66 */
67 @Nonnull
68 <T> Supplier<T> scope(@Nonnull Key<T> key, @Nonnull Supplier<T> unscoped);
69 }