com.google.inject.multibindings.OptionalBinderBinding Maven / Gradle / Ivy
/**
* 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.
*
* Although OptionalBinders may be injected through a variety of types
* {@code T}, {@code Optional}, {@code Optional>}, etc..), an
* OptionalBinderBinding exists only on the Binding associated with the
* {@code Optional} key. Other bindings can be validated to be derived from this
* OptionalBinderBinding using {@link #containsElement}.
*
* @param The fully qualified type of the optional binding, including Optional.
* For example: {@code Optional}.
*
* @since 4.0
* @author [email protected] (Sam Berlin)
*/
public interface OptionalBinderBinding {
/** Returns the {@link Key} for this binding. */
Key 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}.
*
* The Binding's type will always match the type Optional's generic type. For example, if getKey
* returns a key of Optional<String>, then this will always return a
* Binding<String>.
*/
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}.
*
* The Binding's type will always match the type Optional's generic type. For example, if getKey
* returns a key of Optional<String>, then this will always return a
* Binding<String>.
*/
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);
}