/*
 * 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.Map;
import java.util.Set;

A binding for a MapBinder.
Although MapBinders may be injected through a variety of generic types (Map<K, V>, Map<K, Provider<V>>, Map<K, Set<V>>, {@ocde Map>}, and even Set<Map.Entry<K, Provider<V>>), a MapBinderBinding exists only on the Binding associated with the Map<K, V> key. Injectable map types can be discovered using getMapKey (which will return the Map<K, V> key), orgetAlternateMapKeys (which will return the other keys that can inject this data). Other bindings can be validated to be derived from this MapBinderBinding using containsElement(Element). 
Author:
sameb@google.com (Sam Berlin)
Type parameters:
<T> – The fully qualified type of the map, including Map. For example: 
    MapBinderBinding<Map<String, Snack>>
Since:
3.0/**
 * A binding for a MapBinder.
 *
 * <p>Although MapBinders may be injected through a variety of generic types ({@code Map<K, V>},
 * {@code Map<K, Provider<V>>}, {@code Map<K, Set<V>>}, {@ocde Map<K, Set<Provider<V>>}, and even
 * {@code Set<Map.Entry<K, Provider<V>>}), a MapBinderBinding exists only on the Binding associated
 * with the Map&lt;K, V> key. Injectable map types can be discovered using {@link #getMapKey} (which
 * will return the {@code Map<K, V>} key), or{@link #getAlternateMapKeys} (which will return the
 * other keys that can inject this data). Other bindings can be validated to be derived from this
 * MapBinderBinding using {@link #containsElement(Element)}.
 *
 * @param <T> The fully qualified type of the map, including Map. For example: {@code
 *     MapBinderBinding<Map<String, Snack>>}
 * @since 3.0
 * @author sameb@google.com (Sam Berlin)
 */
public interface MapBinderBinding<T> {

  
Returns the Key for the map. /** Returns the {@link Key} for the map. */
  Key<T> getMapKey();

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

  
Returns the TypeLiteral describing the keys of the map.
The TypeLiteral will always match the type Map's generic type. For example, if getMapKey
returns a key of Map<String, Snack>, then this will always return a 
TypeLiteral<String>.
/**
   * Returns the TypeLiteral describing the keys of the map.
   *
   * <p>The TypeLiteral will always match the type Map's generic type. For example, if getMapKey
   * returns a key of <code>Map&lt;String, Snack></code>, then this will always return a <code>
   * TypeLiteral&lt;String></code>.
   */
  TypeLiteral<?> getKeyTypeLiteral();

  
Returns the TypeLiteral describing the values of the map.
The TypeLiteral will always match the type Map's generic type. For example, if getMapKey
returns a key of Map<String, Snack>, then this will always return a 
TypeLiteral<Snack>.
/**
   * Returns the TypeLiteral describing the values of the map.
   *
   * <p>The TypeLiteral will always match the type Map's generic type. For example, if getMapKey
   * returns a key of <code>Map&lt;String, Snack></code>, then this will always return a <code>
   * TypeLiteral&lt;Snack></code>.
   */
  TypeLiteral<?> getValueTypeLiteral();

  
Returns all entries in the Map. The returned list of Map.Entries contains the key and a binding to the value. Duplicate keys or values will exist as separate Map.Entries in the returned list. 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 Map's generic type. For example, if getMapKey
returns a key of Map<String, Snack>, then this will always return a list of
type List<Map.Entry<String, Binding<Snack>>>.
/**
   * Returns all entries in the Map. The returned list of Map.Entries contains the key and a binding
   * to the value. Duplicate keys or values will exist as separate Map.Entries in the returned list.
   * 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 Map's generic type. For example, if getMapKey
   * returns a key of <code>Map&lt;String, Snack></code>, then this will always return a list of
   * type <code>List&lt;Map.Entry&lt;String, Binding&lt;Snack>>></code>.
   */
  List<Map.Entry<?, Binding<?>>> getEntries();

  
Similar to getEntries(), but can be used on a MapBinderBinding retrieved from Elements.getElements. 
One way to use this is to pass in the results of Elements.getElements as the 
elements parameter. 
This differs from getEntries() in that it will return duplicates if they are present in the elements passed in. This does not run the normal Guice de-duplication that getEntries() does. 
Throws:
IllegalArgumentException – if the provided elements contain partial map entries. If the elements come from Elements.getElements on a module with a MapBinder, there will be a 1:1 relationship and no exception will be thrown.
Since:
4.2/**
   * Similar to {@link #getEntries()}, but can be used on a MapBinderBinding retrieved from {@link
   * Elements#getElements}.
   *
   * <p>One way to use this is to pass in the results of {@link Elements#getElements} as the {@code
   * elements} parameter.
   *
   * <p>This differs from {@link #getEntries()} in that it will return duplicates if they are
   * present in the {@code elements} passed in. This does not run the normal Guice de-duplication
   * that {@link #getEntries()} does.
   *
   * @throws IllegalArgumentException if the provided elements contain partial map entries. If the
   *     elements come from {@link Elements#getElements} on a module with a MapBinder, there will be
   *     a 1:1 relationship and no exception will be thrown.
   * @since 4.2
   */
  List<Map.Entry<?, Binding<?>>> getEntries(Iterable<? extends Element> elements);

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

  
Returns true if this MapBinder contains the given Element in order to build the map or uses the given Element in order to support building and injecting the map. This will work for MapBinderBindings 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 getEntries and permitsDuplicates are better options. 
If you need to introspect the details of the map, such as the keys, values or if it permits duplicates, it is necessary to pass the elements through an Injector and use getEntries() and permitsDuplicates(). /**
   * Returns true if this MapBinder contains the given Element in order to build the map or uses the
   * given Element in order to support building and injecting the map. This will work for
   * MapBinderBindings 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 #getEntries} and {@link #permitsDuplicates} are better options.
   *
   * <p>If you need to introspect the details of the map, such as the keys, values or if it permits
   * duplicates, it is necessary to pass the elements through an Injector and use {@link
   * #getEntries()} and {@link #permitsDuplicates()}.
   */
  boolean containsElement(Element element);
}