extensions/multibindings/src/com/google/inject/multibindings/ProvidesIntoMap.java

/**
 * Copyright (C) 2015 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 static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

import com.google.inject.Module;

import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

/**
 * Annotates methods of a {@link Module} to add items to a {@link MapBinder}.
 * The method's return type, binding annotation and additional key annotation determines
 * what Map this will contribute to. For example,
 *
 * <pre>
 * {@literal @}ProvidesIntoMap
 * {@literal @}StringMapKey("Foo")
 * {@literal @}Named("plugins")
 * Plugin provideFooUrl(FooManager fm) { returm fm.getPlugin(); }
 *
 * {@literal @}ProvidesIntoMap
 * {@literal @}StringMapKey("Bar")
 * {@literal @}Named("urls")
 * Plugin provideBarUrl(BarManager bm) { return bm.getPlugin(); }
 * </pre>
 *
 * will add two items to the {@code @Named("urls") Map<String, Plugin>} map. The key 'Foo'
 * will map to the provideFooUrl method, and the key 'Bar' will map to the provideBarUrl method.
 * The values are bound as providers and will be evaluated at injection time.
 *
 * <p>Because the key is specified as an annotation, only Strings, Classes, enums, primitive
 * types and annotation instances are supported as keys.
 *
 * @author sameb@google.com (Sam Berlin)
 * @since 4.0
 */
@Documented
@Target(METHOD)
@Retention(RUNTIME)
public @interface ProvidesIntoMap {
}