1/**
2 * Copyright (C) 2008 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.spi;
18
19import com.google.inject.Binding;
20
21/**
22 * No-op visitor for subclassing. All interface methods simply delegate to {@link
23 * #visitOther(Binding)}, returning its result.
24 *
25 * @param <V> any type to be returned by the visit method. Use {@link Void} with
26 *     {@code return null} if no return type is needed.
27 *
28 * @author jessewilson@google.com (Jesse Wilson)
29 * @since 2.0
30 */
31public abstract class DefaultBindingTargetVisitor<T, V> implements BindingTargetVisitor<T, V> {
32
33  /**
34   * Default visit implementation. Returns {@code null}.
35   */
36  protected V visitOther(Binding<? extends T> binding) {
37    return null;
38  }
39
40  public V visit(InstanceBinding<? extends T> instanceBinding) {
41    return visitOther(instanceBinding);
42  }
43
44  public V visit(ProviderInstanceBinding<? extends T> providerInstanceBinding) {
45    return visitOther(providerInstanceBinding);
46  }
47
48  public V visit(ProviderKeyBinding<? extends T> providerKeyBinding) {
49    return visitOther(providerKeyBinding);
50  }
51
52  public V visit(LinkedKeyBinding<? extends T> linkedKeyBinding) {
53    return visitOther(linkedKeyBinding);
54  }
55
56  public V visit(ExposedBinding<? extends T> exposedBinding) {
57    return visitOther(exposedBinding);
58  }
59
60  public V visit(UntargettedBinding<? extends T> untargettedBinding) {
61    return visitOther(untargettedBinding);
62  }
63
64  public V visit(ConstructorBinding<? extends T> constructorBinding) {
65    return visitOther(constructorBinding);
66  }
67
68  public V visit(ConvertedConstantBinding<? extends T> convertedConstantBinding) {
69    return visitOther(convertedConstantBinding);
70  }
71
72  @SuppressWarnings("unchecked")
73  public V visit(ProviderBinding<? extends T> providerBinding) {
74    // TODO(cushon): remove raw (Binding) cast when we don't care about javac 6 anymore
75    return visitOther((Binding<? extends T>) (Binding) providerBinding);
76  }
77}
78