| /* |
| * Copyright (C) 2014 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.multibindings; |
| |
| import com.google.inject.Binding; |
| import com.google.inject.Key; |
| import com.google.inject.spi.Element; |
| import com.google.inject.spi.Elements; |
| |
| /** |
| * A binding for a OptionalBinder. |
| * |
| * <p>Although OptionalBinders may be injected through a variety of types {@code T}, {@code |
| * Optional<T>}, {@code Optional<Provider<T>>}, etc..), an OptionalBinderBinding exists only on the |
| * Binding associated with the {@code Optional<T>} key. Other bindings can be validated to be |
| * derived from this OptionalBinderBinding using {@link #containsElement}. |
| * |
| * @param <T> The fully qualified type of the optional binding, including Optional. For example: |
| * {@code Optional<String>}. |
| * @since 4.0 |
| * @author sameb@google.com (Sam Berlin) |
| */ |
| public interface OptionalBinderBinding<T> { |
| |
| /** Returns the {@link Key} for this binding. */ |
| Key<T> getKey(); |
| |
| /** |
| * Returns the default binding (set by {@link OptionalBinder#setDefault}) if one exists or null if |
| * no default binding is set. This will throw {@link UnsupportedOperationException} if it is |
| * called on an element retrieved from {@link Elements#getElements}. |
| * |
| * <p>The Binding's type will always match the type Optional's generic type. For example, if |
| * getKey returns a key of <code>Optional<String></code>, then this will always return a <code> |
| * Binding<String></code>. |
| */ |
| Binding<?> getDefaultBinding(); |
| |
| /** |
| * Returns the actual binding (set by {@link OptionalBinder#setBinding}) or null if not set. This |
| * will throw {@link UnsupportedOperationException} if it is called on an element retrieved from |
| * {@link Elements#getElements}. |
| * |
| * <p>The Binding's type will always match the type Optional's generic type. For example, if |
| * getKey returns a key of <code>Optional<String></code>, then this will always return a <code> |
| * Binding<String></code>. |
| */ |
| Binding<?> getActualBinding(); |
| |
| /** |
| * Returns true if this OptionalBinder contains the given Element in order to build the optional |
| * binding or uses the given Element in order to support building and injecting its data. This |
| * will work for OptionalBinderBinding retrieved from an injector and {@link |
| * Elements#getElements}. Usually this is only necessary if you are working with elements |
| * retrieved from modules (without an Injector), otherwise {@link #getDefaultBinding} and {@link |
| * #getActualBinding} are better options. |
| */ |
| boolean containsElement(Element element); |
| } |