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;
26import java.util.Map;
27
28/**
29 * A binding for a MapBinder.
30 * <p>
31 * Although MapBinders may be injected through a variety of generic types (Map&lt;K, V>, Map
32 * &lt;K, Provider&lt;V>>, Map&lt;K, Set&lt;V>>, Map<K, Set&lt;
33 * Provider&lt;V>>, and even Set&lt;Map.Entry&lt;K, Provider&lt;V>>), a
34 * MapBinderBinding exists only on the Binding associated with the Map&lt;K, V> key. Other
35 * bindings can be validated to be derived from this MapBinderBinding using
36 * {@link #containsElement(Element)}.
37 *
38 * @param <T> The fully qualified type of the map, including Map. For example:
39 *          <code>MapBinderBinding&lt;Map&lt;String, Snack>></code>
40 *
41 * @since 3.0
42 * @author sameb@google.com (Sam Berlin)
43 */
44public interface MapBinderBinding<T> {
45
46  /** Returns the {@link Key} for the map. */
47  Key<T> getMapKey();
48
49  /**
50   * Returns the TypeLiteral describing the keys of the map.
51   * <p>
52   * The TypeLiteral will always match the type Map's generic type. For example, if getMapKey
53   * returns a key of <code>Map&lt;String, Snack></code>, then this will always return a
54   * <code>TypeLiteral&lt;String></code>.
55   */
56  TypeLiteral<?> getKeyTypeLiteral();
57
58  /**
59   * Returns the TypeLiteral describing the values of the map.
60   * <p>
61   * The TypeLiteral will always match the type Map's generic type. For example, if getMapKey
62   * returns a key of <code>Map&lt;String, Snack></code>, then this will always return a
63   * <code>TypeLiteral&lt;Snack></code>.
64   */
65  TypeLiteral<?> getValueTypeLiteral();
66
67  /**
68   * Returns all entries in the Map. The returned list of Map.Entries contains the key and a binding
69   * to the value. Duplicate keys or values will exist as separate Map.Entries in the returned list.
70   * This is only supported on bindings returned from an injector. This will throw
71   * {@link UnsupportedOperationException} if it is called on an element retrieved from
72   * {@link Elements#getElements}.
73   * <p>
74   * The elements will always match the type Map's generic type. For example, if getMapKey returns a
75   * key of <code>Map&lt;String, Snack></code>, then this will always return a list of type
76   * <code>List&lt;Map.Entry&lt;String, Binding&lt;Snack>>></code>.
77   */
78  List<Map.Entry<?, Binding<?>>> getEntries();
79
80  /**
81   * Returns true if the MapBinder permits duplicates. This is only supported on bindings returned
82   * from an injector. This will throw {@link UnsupportedOperationException} if it is called on a
83   * MapBinderBinding retrieved from {@link Elements#getElements}.
84   */
85  boolean permitsDuplicates();
86
87  /**
88   * Returns true if this MapBinder contains the given Element in order to build the map or uses the
89   * given Element in order to support building and injecting the map. This will work for
90   * MapBinderBindings retrieved from an injector and {@link Elements#getElements}. Usually this is
91   * only necessary if you are working with elements retrieved from modules (without an Injector),
92   * otherwise {@link #getEntries} and {@link #permitsDuplicates} are better options.
93   * <p>
94   * If you need to introspect the details of the map, such as the keys, values or if it permits
95   * duplicates, it is necessary to pass the elements through an Injector and use
96   * {@link #getEntries()} and {@link #permitsDuplicates()}.
97   */
98  boolean containsElement(Element element);
99}
100