| /** |
| * Copyright (C) 2010 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.inject.spi; |
| |
| import com.google.inject.Binding; |
| import com.google.inject.Provider; |
| |
| /** |
| * A Provider that is part of an extension which supports a custom |
| * BindingTargetVisitor. |
| * <p> |
| * When an extension binds a provider instance, the provider can implement this |
| * interface to allow users using the |
| * {@link Binding#acceptTargetVisitor(BindingTargetVisitor)} method to visit a |
| * custom visitor designed for that extension. A typical implementation within |
| * the extension would look like |
| * <pre> |
| * <code> |
| * {@literal<}V, B> V acceptExtensionVisitor(BindingTargetVisitor{@literal<}B, V> visitor, ProviderInstanceBinding{@literal<}? extends B> binding) { |
| * if(visitor instanceof MyCustomExtensionVisitor) { |
| * return ((MyCustomExtensionVisitor{@literal<}B, V>)visitor).visitCustomExtension(customProperties, binding); |
| * } else { |
| * return visitor.visit(binding); |
| * } |
| * } |
| * </code> |
| * </pre> |
| * 'MyCustomExtensionVisitor' in the example above would be an interface the |
| * extension provides that users can implement in order to be notified of custom |
| * extension information. These visitor interfaces must extend from |
| * BindingTargetVisitor. |
| * |
| * @author sameb@google.com (Sam Berlin) |
| */ |
| public interface ProviderWithExtensionVisitor<T> extends Provider<T> { |
| |
| /** |
| * Instructs the extension determine if the visitor is an instance of a custom |
| * extension visitor, and if so, visit it using that method. If the visitor is |
| * not an instance of the custom extension visitor, this method <b>MUST</b> |
| * call visitor.visit(binding). |
| * <p> |
| * Due to issues with generics, the type parameters of this method do not |
| * relate to the type of the provider. In practice, the 'B' type will always |
| * be a supertype of 'T'. |
| */ |
| <V, B> V acceptExtensionVisitor(BindingTargetVisitor<B, V> visitor, |
| ProviderInstanceBinding<? extends B> binding); |
| } |