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 17 package com.google.inject.spi; 18 19 import 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 {@code return null} 26 * if no return type is needed. 27 * @author jessewilson@google.com (Jesse Wilson) 28 * @since 2.0 29 */ 30 public abstract class DefaultBindingTargetVisitor<T, V> implements BindingTargetVisitor<T, V> { 31 32 /** Default visit implementation. Returns {@code null}. */ visitOther(Binding<? extends T> binding)33 protected V visitOther(Binding<? extends T> binding) { 34 return null; 35 } 36 37 @Override visit(InstanceBinding<? extends T> instanceBinding)38 public V visit(InstanceBinding<? extends T> instanceBinding) { 39 return visitOther(instanceBinding); 40 } 41 42 @Override visit(ProviderInstanceBinding<? extends T> providerInstanceBinding)43 public V visit(ProviderInstanceBinding<? extends T> providerInstanceBinding) { 44 return visitOther(providerInstanceBinding); 45 } 46 47 @Override visit(ProviderKeyBinding<? extends T> providerKeyBinding)48 public V visit(ProviderKeyBinding<? extends T> providerKeyBinding) { 49 return visitOther(providerKeyBinding); 50 } 51 52 @Override visit(LinkedKeyBinding<? extends T> linkedKeyBinding)53 public V visit(LinkedKeyBinding<? extends T> linkedKeyBinding) { 54 return visitOther(linkedKeyBinding); 55 } 56 57 @Override visit(ExposedBinding<? extends T> exposedBinding)58 public V visit(ExposedBinding<? extends T> exposedBinding) { 59 return visitOther(exposedBinding); 60 } 61 62 @Override visit(UntargettedBinding<? extends T> untargettedBinding)63 public V visit(UntargettedBinding<? extends T> untargettedBinding) { 64 return visitOther(untargettedBinding); 65 } 66 67 @Override visit(ConstructorBinding<? extends T> constructorBinding)68 public V visit(ConstructorBinding<? extends T> constructorBinding) { 69 return visitOther(constructorBinding); 70 } 71 72 @Override visit(ConvertedConstantBinding<? extends T> convertedConstantBinding)73 public V visit(ConvertedConstantBinding<? extends T> convertedConstantBinding) { 74 return visitOther(convertedConstantBinding); 75 } 76 77 @Override 78 @SuppressWarnings("unchecked") visit(ProviderBinding<? extends T> providerBinding)79 public V visit(ProviderBinding<? extends T> providerBinding) { 80 // TODO(cushon): remove raw (Binding) cast when we don't care about javac 6 anymore 81 return visitOther((Binding<? extends T>) (Binding) providerBinding); 82 } 83 } 84