/*
 * 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.multibindings;

import com.google.inject.Binding;
import com.google.inject.Key;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.Element;
import com.google.inject.spi.Elements;
import java.util.List;
import java.util.Set;

A binding for a Multibinder.
Although Multibinders may be injected through a variety of generic types (Set<V> and Collection<Provider<V>>), a MultibinderBinding exists only on the Binding associated with the Set<V> key. Injectable types can be discovered using getSetKey (which will return the Set<V> key), orgetAlternateSetKeys (which will return the other keys that can inject this data). Other bindings can be validated to be derived from this MultibinderBinding using containsElement(Element). 
Author:
sameb@google.com (Sam Berlin)
Type parameters:
<T> – The fully qualified type of the set, including Set. For example: 
    MultibinderBinding<Set<Boolean>>
Since:
3.0/**
 * A binding for a Multibinder.
 *
 * <p>Although Multibinders may be injected through a variety of generic types ({@code Set<V>} and
 * {@code Collection<Provider<V>>}), a MultibinderBinding exists only on the Binding associated with
 * the {@code Set<V>} key. Injectable types can be discovered using {@link #getSetKey} (which will
 * return the {@code Set<V>} key), or{@link #getAlternateSetKeys} (which will return the other keys
 * that can inject this data). Other bindings can be validated to be derived from this
 * MultibinderBinding using {@link #containsElement(Element)}.
 *
 * @param <T> The fully qualified type of the set, including Set. For example: {@code
 *     MultibinderBinding<Set<Boolean>>}
 * @since 3.0
 * @author sameb@google.com (Sam Berlin)
 */
public interface MultibinderBinding<T> {

  
Returns the key for the set. /** Returns the key for the set. */
  Key<T> getSetKey();

  
Returns the keys of other bindings that represent this set. This will return an entry for Collection<com.google.inject.Provider<V>> and 
Collection<javax.inject.Provider<V>>. 
Since:
4.2.3/**
   * Returns the keys of other bindings that represent this set. This will return an entry for
   * {@code Collection<com.google.inject.Provider<V>>} and {@code
   * Collection<javax.inject.Provider<V>>}.
   *
   * @since 4.2.3
   */
  Set<Key<?>> getAlternateSetKeys();

  
Returns the TypeLiteral that describes the type of elements in the set.
The elements will always match the type Set's generic type. For example, if getSetKey
returns a key of Set<String>, then this will always return a 
TypeLiteral<String>.
/**
   * Returns the TypeLiteral that describes the type of elements in the set.
   *
   * <p>The elements will always match the type Set's generic type. For example, if getSetKey
   * returns a key of <code>Set&lt;String></code>, then this will always return a <code>
   * TypeLiteral&lt;String></code>.
   */
  TypeLiteral<?> getElementTypeLiteral();

  
Returns all bindings that make up the set. This is only supported on bindings returned from an injector. This will throw UnsupportedOperationException if it is called on an element retrieved from Elements.getElements. 
The elements will always match the type Set's generic type. For example, if getSetKey
returns a key of Set<String>, then this will always return a list of type
List<Binding<String>>.
/**
   * Returns all bindings that make up the set. This is only supported on bindings returned from an
   * injector. This will throw {@link UnsupportedOperationException} if it is called on an element
   * retrieved from {@link Elements#getElements}.
   *
   * <p>The elements will always match the type Set's generic type. For example, if getSetKey
   * returns a key of <code>Set&lt;String></code>, then this will always return a list of type
   * <code>List&lt;Binding&lt;String>></code>.
   */
  List<Binding<?>> getElements();

  
Returns true if the multibinder permits duplicates. This is only supported on bindings returned from an injector. This will throw UnsupportedOperationException if it is called on a MultibinderBinding retrieved from Elements.getElements. /**
   * Returns true if the multibinder permits duplicates. This is only supported on bindings returned
   * from an injector. This will throw {@link UnsupportedOperationException} if it is called on a
   * MultibinderBinding retrieved from {@link Elements#getElements}.
   */
  boolean permitsDuplicates();

  
Returns true if this Multibinder uses the given Element. This will be true for bindings that derive the elements of the set and other bindings that Multibinder uses internally. This will work for MultibinderBindings retrieved from an injector and Elements.getElements. Usually this is only necessary if you are working with elements retrieved from modules (without an Injector), otherwise getElements and permitsDuplicates are better options. 
If you need to introspect the details of the set, such as the values or if it permits duplicates, it is necessary to pass the elements through an Injector and use getElements() and permitsDuplicates(). /**
   * Returns true if this Multibinder uses the given Element. This will be true for bindings that
   * derive the elements of the set and other bindings that Multibinder uses internally. This will
   * work for MultibinderBindings 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 #getElements} and {@link #permitsDuplicates} are better options.
   *
   * <p>If you need to introspect the details of the set, such as the values or if it permits
   * duplicates, it is necessary to pass the elements through an Injector and use {@link
   * #getElements()} and {@link #permitsDuplicates()}.
   */
  boolean containsElement(Element element);
}