1/**
2 * Copyright (C) 2010 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.inject.multibindings;
18
19import com.google.inject.Binding;
20import com.google.inject.Key;
21import com.google.inject.TypeLiteral;
22import com.google.inject.spi.Element;
23import com.google.inject.spi.Elements;
24
25import java.util.List;
26
27/**
28 * A binding for a Multibinder.
29 *
30 * @param <T> The fully qualified type of the set, including Set. For example:
31 *          <code>MultibinderBinding&lt;Set&lt;Boolean>></code>
32 *
33 * @since 3.0
34 * @author sameb@google.com (Sam Berlin)
35 */
36public interface MultibinderBinding<T> {
37
38  /** Returns the key for the set. */
39  Key<T> getSetKey();
40
41  /**
42   * Returns the TypeLiteral that describes the type of elements in the set.
43   * <p>
44   * The elements will always match the type Set's generic type. For example, if getSetKey returns a
45   * key of <code>Set&lt;String></code>, then this will always return a
46   * <code>TypeLiteral&lt;String></code>.
47   */
48  TypeLiteral<?> getElementTypeLiteral();
49
50  /**
51   * Returns all bindings that make up the set. This is only supported on bindings returned from an
52   * injector. This will throw {@link UnsupportedOperationException} if it is called on an element
53   * retrieved from {@link Elements#getElements}.
54   * <p>
55   * The elements will always match the type Set's generic type. For example, if getSetKey returns a
56   * key of <code>Set&lt;String></code>, then this will always return a list of type
57   * <code>List&lt;Binding&lt;String>></code>.
58   */
59  List<Binding<?>> getElements();
60
61  /**
62   * Returns true if the multibinder permits duplicates. This is only supported on bindings returned
63   * from an injector. This will throw {@link UnsupportedOperationException} if it is called on a
64   * MultibinderBinding retrieved from {@link Elements#getElements}.
65   */
66  boolean permitsDuplicates();
67
68  /**
69   * Returns true if this Multibinder uses the given Element. This will be true for bindings that
70   * derive the elements of the set and other bindings that Multibinder uses internally. This will
71   * work for MultibinderBindings retrieved from an injector and {@link Elements#getElements}.
72   * Usually this is only necessary if you are working with elements retrieved from modules (without
73   * an Injector), otherwise {@link #getElements} and {@link #permitsDuplicates} are better options.
74   * <p>
75   * If you need to introspect the details of the set, such as the values or if it permits
76   * duplicates, it is necessary to pass the elements through an Injector and use
77   * {@link #getElements()} and {@link #permitsDuplicates()}.
78   */
79  boolean containsElement(Element element);
80}
81