com.google.inject.multibindings.MapBinder Maven / Gradle / Ivy
/**
* Copyright (C) 2008 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.Binder;
import com.google.inject.Binding;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.TypeLiteral;
import com.google.inject.binder.LinkedBindingBuilder;
import com.google.inject.internal.util.ImmutableList;
import com.google.inject.internal.util.ImmutableMap;
import com.google.inject.internal.util.ImmutableSet;
import com.google.inject.internal.util.Lists;
import com.google.inject.multibindings.Multibinder.RealMultibinder;
import static com.google.inject.multibindings.Multibinder.checkConfiguration;
import static com.google.inject.multibindings.Multibinder.checkNotNull;
import static com.google.inject.multibindings.Multibinder.setOf;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderLookup;
import com.google.inject.spi.ProviderWithDependencies;
import com.google.inject.spi.ProviderWithExtensionVisitor;
import com.google.inject.spi.Toolable;
import com.google.inject.util.Types;
import static com.google.inject.util.Types.newParameterizedTypeWithOwner;
import java.lang.annotation.Annotation;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
/**
* An API to bind multiple map entries separately, only to later inject them as
* a complete map. MapBinder is intended for use in your application's module:
*
* public class SnacksModule extends AbstractModule {
* protected void configure() {
* MapBinder<String, Snack> mapbinder
* = MapBinder.newMapBinder(binder(), String.class, Snack.class);
* mapbinder.addBinding("twix").toInstance(new Twix());
* mapbinder.addBinding("snickers").toProvider(SnickersProvider.class);
* mapbinder.addBinding("skittles").to(Skittles.class);
* }
* }
*
* With this binding, a {@link Map}{@code } can now be
* injected:
*
* class SnackMachine {
* {@literal @}Inject
* public SnackMachine(Map<String, Snack> snacks) { ... }
* }
*
* In addition to binding {@code Map}, a mapbinder will also bind
* {@code Map>} for lazy value provision:
*
* class SnackMachine {
* {@literal @}Inject
* public SnackMachine(Map<String, Provider<Snack>> snackProviders) { ... }
* }
*
* Contributing mapbindings from different modules is supported. For example,
* it is okay to have both {@code CandyModule} and {@code ChipsModule} both
* create their own {@code MapBinder}, and to each contribute
* bindings to the snacks map. When that map is injected, it will contain
* entries from both modules.
*
* The map's iteration order is consistent with the binding order. This is
* convenient when multiple elements are contributed by the same module because
* that module can order its bindings appropriately. Avoid relying on the
* iteration order of elements contributed by different modules, since there is
* no equivalent mechanism to order modules.
*
*
The map is unmodifiable. Elements can only be added to the map by
* configuring the MapBinder. Elements can never be removed from the map.
*
*
Values are resolved at map injection time. If a value is bound to a
* provider, that provider's get method will be called each time the map is
* injected (unless the binding is also scoped, or a map of providers is injected).
*
*
Annotations are used to create different maps of the same key/value
* type. Each distinct annotation gets its own independent map.
*
*
Keys must be distinct. If the same key is bound more than
* once, map injection will fail. However, use {@link #permitDuplicates()} in
* order to allow duplicate keys; extra bindings to {@code Map>} and
* {@code Map>} will be added.
*
* Keys must be non-null. {@code addBinding(null)} will
* throw an unchecked exception.
*
*
Values must be non-null to use map injection. If any
* value is null, map injection will fail (although injecting a map of providers
* will not).
*
* @author [email protected] (David P. Baker)
*/
public abstract class MapBinder {
private MapBinder() {}
/**
* Returns a new mapbinder that collects entries of {@code keyType}/{@code valueType} in a
* {@link Map} that is itself bound with no binding annotation.
*/
public static MapBinder newMapBinder(Binder binder,
TypeLiteral keyType, TypeLiteral valueType) {
binder = binder.skipSources(MapBinder.class, RealMapBinder.class);
return newMapBinder(binder, keyType, valueType,
Key.get(mapOf(keyType, valueType)),
Key.get(mapOfProviderOf(keyType, valueType)),
Key.get(mapOf(keyType, setOf(valueType))),
Key.get(mapOfSetOfProviderOf(keyType, valueType)),
Multibinder.newSetBinder(binder, entryOfProviderOf(keyType, valueType)));
}
/**
* Returns a new mapbinder that collects entries of {@code keyType}/{@code valueType} in a
* {@link Map} that is itself bound with no binding annotation.
*/
public static MapBinder newMapBinder(Binder binder,
Class keyType, Class valueType) {
return newMapBinder(binder, TypeLiteral.get(keyType), TypeLiteral.get(valueType));
}
/**
* Returns a new mapbinder that collects entries of {@code keyType}/{@code valueType} in a
* {@link Map} that is itself bound with {@code annotation}.
*/
public static MapBinder newMapBinder(Binder binder,
TypeLiteral keyType, TypeLiteral valueType, Annotation annotation) {
binder = binder.skipSources(MapBinder.class, RealMapBinder.class);
return newMapBinder(binder, keyType, valueType,
Key.get(mapOf(keyType, valueType), annotation),
Key.get(mapOfProviderOf(keyType, valueType), annotation),
Key.get(mapOf(keyType, setOf(valueType)), annotation),
Key.get(mapOfSetOfProviderOf(keyType, valueType), annotation),
Multibinder.newSetBinder(binder, entryOfProviderOf(keyType, valueType), annotation));
}
/**
* Returns a new mapbinder that collects entries of {@code keyType}/{@code valueType} in a
* {@link Map} that is itself bound with {@code annotation}.
*/
public static MapBinder newMapBinder(Binder binder,
Class keyType, Class valueType, Annotation annotation) {
return newMapBinder(binder, TypeLiteral.get(keyType), TypeLiteral.get(valueType), annotation);
}
/**
* Returns a new mapbinder that collects entries of {@code keyType}/{@code valueType} in a
* {@link Map} that is itself bound with {@code annotationType}.
*/
public static MapBinder newMapBinder(Binder binder, TypeLiteral keyType,
TypeLiteral valueType, Class annotationType) {
binder = binder.skipSources(MapBinder.class, RealMapBinder.class);
return newMapBinder(binder, keyType, valueType,
Key.get(mapOf(keyType, valueType), annotationType),
Key.get(mapOfProviderOf(keyType, valueType), annotationType),
Key.get(mapOf(keyType, setOf(valueType)), annotationType),
Key.get(mapOfSetOfProviderOf(keyType, valueType), annotationType),
Multibinder.newSetBinder(binder, entryOfProviderOf(keyType, valueType), annotationType));
}
/**
* Returns a new mapbinder that collects entries of {@code keyType}/{@code valueType} in a
* {@link Map} that is itself bound with {@code annotationType}.
*/
public static MapBinder newMapBinder(Binder binder, Class keyType,
Class valueType, Class annotationType) {
return newMapBinder(
binder, TypeLiteral.get(keyType), TypeLiteral.get(valueType), annotationType);
}
@SuppressWarnings("unchecked") // a map of is safely a Map
static TypeLiteral> mapOf(
TypeLiteral keyType, TypeLiteral valueType) {
return (TypeLiteral>) TypeLiteral.get(
Types.mapOf(keyType.getType(), valueType.getType()));
}
@SuppressWarnings("unchecked") // a provider map is safely a Map>
static TypeLiteral>> mapOfProviderOf(
TypeLiteral keyType, TypeLiteral valueType) {
return (TypeLiteral>>) TypeLiteral.get(
Types.mapOf(keyType.getType(), Types.providerOf(valueType.getType())));
}
@SuppressWarnings("unchecked") // a provider map > is safely a Map>>
static TypeLiteral>>> mapOfSetOfProviderOf(
TypeLiteral keyType, TypeLiteral valueType) {
return (TypeLiteral>>>) TypeLiteral.get(
Types.mapOf(keyType.getType(), Types.setOf(Types.providerOf(valueType.getType()))));
}
@SuppressWarnings("unchecked") // a provider entry is safely a Map.Entry>
static TypeLiteral>> entryOfProviderOf(
TypeLiteral keyType, TypeLiteral valueType) {
return (TypeLiteral>>) TypeLiteral.get(newParameterizedTypeWithOwner(
Map.class, Entry.class, keyType.getType(), Types.providerOf(valueType.getType())));
}
private static MapBinder newMapBinder(Binder binder,
TypeLiteral keyType, TypeLiteral valueType,
Key> mapKey, Key>> providerMapKey,
Key>> multimapKey, Key>>> providerMultimapKey,
Multibinder>> entrySetBinder) {
RealMapBinder mapBinder = new RealMapBinder(
binder, keyType, valueType, mapKey, providerMapKey, multimapKey,
providerMultimapKey, entrySetBinder);
binder.install(mapBinder);
return mapBinder;
}
/**
* Configures the {@code MapBinder} to handle duplicate entries.
* When multiple equal keys are bound, the value that gets included in the map is
* arbitrary.
*
In addition to the {@code Map} and {@code Map>}
* maps that are normally bound, a {@code Map>} and
* {@code Map>>} are also bound, which contain
* all values bound to each key.
*
* When multiple modules contribute elements to the map, this configuration
* option impacts all of them.
*
* @return this map binder
* @since 3.0
*/
public abstract MapBinder permitDuplicates();
/**
* Returns a binding builder used to add a new entry in the map. Each
* key must be distinct (and non-null). Bound providers will be evaluated each
* time the map is injected.
*
* It is an error to call this method without also calling one of the
* {@code to} methods on the returned binding builder.
*
*
Scoping elements independently is supported. Use the {@code in} method
* to specify a binding scope.
*/
public abstract LinkedBindingBuilder addBinding(K key);
/**
* The actual mapbinder plays several roles:
*
* As a MapBinder, it acts as a factory for LinkedBindingBuilders for
* each of the map's values. It delegates to a {@link Multibinder} of
* entries (keys to value providers).
*
*
As a Module, it installs the binding to the map itself, as well as to
* a corresponding map whose values are providers. It uses the entry set
* multibinder to construct the map and the provider map.
*
*
As a module, this implements equals() and hashcode() in order to trick
* Guice into executing its configure() method only once. That makes it so
* that multiple mapbinders can be created for the same target map, but
* only one is bound. Since the list of bindings is retrieved from the
* injector itself (and not the mapbinder), each mapbinder has access to
* all contributions from all equivalent mapbinders.
*
*
Rather than binding a single Map.Entry<K, V>, the map binder
* binds keys and values independently. This allows the values to be properly
* scoped.
*
*
We use a subclass to hide 'implements Module' from the public API.
*/
private static final class RealMapBinder extends MapBinder implements Module {
private final TypeLiteral keyType;
private final TypeLiteral valueType;
private final Key> mapKey;
private final Key>> providerMapKey;
private final Key>> multimapKey;
private final Key>>> providerMultimapKey;
private final RealMultibinder>> entrySetBinder;
/* the target injector's binder. non-null until initialization, null afterwards */
private Binder binder;
private boolean permitDuplicates;
private ImmutableList>> mapBindings;
private RealMapBinder(Binder binder, TypeLiteral keyType, TypeLiteral valueType,
Key> mapKey, Key>> providerMapKey,
Key>> multimapKey, Key>>> providerMultimapKey,
Multibinder>> entrySetBinder) {
this.keyType = keyType;
this.valueType = valueType;
this.mapKey = mapKey;
this.providerMapKey = providerMapKey;
this.multimapKey = multimapKey;
this.providerMultimapKey = providerMultimapKey;
this.entrySetBinder = (RealMultibinder>>) entrySetBinder;
this.binder = binder;
}
@Override
public MapBinder permitDuplicates() {
entrySetBinder.permitDuplicates();
binder.install(new MultimapBinder(
multimapKey, providerMultimapKey, entrySetBinder.getSetKey()));
return this;
}
/**
* This creates two bindings. One for the {@code Map.Entry>}
* and another for {@code V}.
*/
@Override public LinkedBindingBuilder addBinding(K key) {
checkNotNull(key, "key");
checkConfiguration(!isInitialized(), "MapBinder was already initialized");
Key valueKey = Key.get(valueType, new RealElement(entrySetBinder.getSetName()));
entrySetBinder.addBinding().toInstance(new MapEntry>(key,
binder.getProvider(valueKey), valueKey));
return binder.bind(valueKey);
}
public void configure(Binder binder) {
checkConfiguration(!isInitialized(), "MapBinder was already initialized");
final ImmutableSet> dependencies
= ImmutableSet.>of(Dependency.get(entrySetBinder.getSetKey()));
// Binds a Map> from a collection of Set>.
final Provider>>> entrySetProvider = binder
.getProvider(entrySetBinder.getSetKey());
binder.bind(providerMapKey).toProvider(new RealMapBinderProviderWithDependencies>>(mapKey) {
private Map> providerMap;
@SuppressWarnings({ "unused", "unchecked" })
@Toolable @Inject void initialize(Injector injector) {
RealMapBinder.this.binder = null;
permitDuplicates = entrySetBinder.permitsDuplicates(injector);
Map> providerMapMutable = new LinkedHashMap>();
List>> bindingsMutable = Lists.newArrayList();
for (Entry> entry : entrySetProvider.get()) {
Provider previous = providerMapMutable.put(entry.getKey(), entry.getValue());
checkConfiguration(previous == null || permitDuplicates,
"Map injection failed due to duplicated key \"%s\"", entry.getKey());
Key valueKey = (Key)((MapEntry)entry).getValueKey();
bindingsMutable.add(new MapEntry(entry.getKey(),
injector.getBinding(valueKey), valueKey));
}
providerMap = ImmutableMap.copyOf(providerMapMutable);
mapBindings = ImmutableList.copyOf(bindingsMutable);
}
public Map> get() {
return providerMap;
}
public Set> getDependencies() {
return dependencies;
}
});
final Provider>> mapProvider = binder.getProvider(providerMapKey);
binder.bind(mapKey).toProvider(new RealMapWithExtensionProvider>(mapKey) {
public Map get() {
Map map = new LinkedHashMap();
for (Entry> entry : mapProvider.get().entrySet()) {
V value = entry.getValue().get();
K key = entry.getKey();
checkConfiguration(value != null,
"Map injection failed due to null value for key \"%s\"", key);
map.put(key, value);
}
return Collections.unmodifiableMap(map);
}
public Set> getDependencies() {
return dependencies;
}
@SuppressWarnings("unchecked")
public R acceptExtensionVisitor(BindingTargetVisitor visitor,
ProviderInstanceBinding binding) {
if (visitor instanceof MultibindingsTargetVisitor) {
return ((MultibindingsTargetVisitor, R>)visitor).visit(this);
} else {
return visitor.visit(binding);
}
}
public Key> getMapKey() {
return mapKey;
}
public TypeLiteral getKeyTypeLiteral() {
return keyType;
}
public TypeLiteral getValueTypeLiteral() {
return valueType;
}
@SuppressWarnings("unchecked")
public List>> getEntries() {
if (isInitialized()) {
return (List)mapBindings; // safe because mapBindings is immutable
} else {
throw new UnsupportedOperationException("getElements() not supported for module bindings");
}
}
public boolean permitsDuplicates() {
if (isInitialized()) {
return permitDuplicates;
} else {
throw new UnsupportedOperationException("permitsDuplicates() not supported for module bindings");
}
}
public boolean containsElement(com.google.inject.spi.Element element) {
if (entrySetBinder.containsElement(element)) {
return true;
} else {
Key key;
if (element instanceof Binding) {
key = ((Binding)element).getKey();
} else if (element instanceof ProviderLookup) {
key = ((ProviderLookup)element).getKey();
} else {
return false; // cannot match;
}
return key.equals(mapKey)
|| key.equals(providerMapKey)
|| key.equals(multimapKey)
|| key.equals(providerMultimapKey)
|| key.equals(entrySetBinder.getSetKey())
|| matchesValueKey(key);
}
}
});
}
/** Returns true if the key indicates this is a value in the map. */
private boolean matchesValueKey(Key key) {
return key.getAnnotation() instanceof Element
&& ((Element) key.getAnnotation()).setName().equals(entrySetBinder.getSetName())
&& key.getTypeLiteral().equals(valueType);
}
private boolean isInitialized() {
return binder == null;
}
@Override public boolean equals(Object o) {
return o instanceof RealMapBinder
&& ((RealMapBinder) o).mapKey.equals(mapKey);
}
@Override public int hashCode() {
return mapKey.hashCode();
}
/**
* Binds {@code Map>} and {{@code Map>>}.
*/
private static final class MultimapBinder implements Module {
private final Key>> multimapKey;
private final Key>>> providerMultimapKey;
private final Key>>> entrySetKey;
public MultimapBinder(
Key>> multimapKey,
Key>>> providerMultimapKey,
Key>>> entrySetKey) {
this.multimapKey = multimapKey;
this.providerMultimapKey = providerMultimapKey;
this.entrySetKey = entrySetKey;
}
public void configure(Binder binder) {
final ImmutableSet> dependencies
= ImmutableSet.>of(Dependency.get(entrySetKey));
final Provider>>> entrySetProvider =
binder.getProvider(entrySetKey);
// Binds a Map>> from a collection of Map> if
// permitDuplicates was called.
binder.bind(providerMultimapKey).toProvider(
new RealMapBinderProviderWithDependencies>>>(multimapKey) {
private Map>> providerMultimap;
@SuppressWarnings("unused")
@Inject void initialize(Injector injector) {
Map>> providerMultimapMutable =
new LinkedHashMap>>();
for (Entry> entry : entrySetProvider.get()) {
if (!providerMultimapMutable.containsKey(entry.getKey())) {
providerMultimapMutable.put(
entry.getKey(), ImmutableSet.>builder());
}
providerMultimapMutable.get(entry.getKey()).add(entry.getValue());
}
ImmutableMap.Builder>> providerMultimapBuilder =
ImmutableMap.builder();
for (Entry>> entry
: providerMultimapMutable.entrySet()) {
providerMultimapBuilder.put(entry.getKey(), entry.getValue().build());
}
providerMultimap = providerMultimapBuilder.build();
}
public Map>> get() {
return providerMultimap;
}
public Set> getDependencies() {
return dependencies;
}
});
final Provider>>> multimapProvider =
binder.getProvider(providerMultimapKey);
binder.bind(multimapKey).toProvider(new RealMapBinderProviderWithDependencies>>(multimapKey) {
public Map> get() {
ImmutableMap.Builder> multimapBuilder = ImmutableMap.builder();
for (Entry>> entry : multimapProvider.get().entrySet()) {
K key = entry.getKey();
ImmutableSet.Builder valuesBuilder = ImmutableSet.builder();
for (Provider valueProvider : entry.getValue()) {
V value = valueProvider.get();
checkConfiguration(value != null,
"Multimap injection failed due to null value for key \"%s\"", key);
valuesBuilder.add(value);
}
multimapBuilder.put(key, valuesBuilder.build());
}
return multimapBuilder.build();
}
public Set> getDependencies() {
return dependencies;
}
});
}
}
private static final class MapEntry implements Map.Entry {
private final K key;
private final V value;
private final Key valueKey;
private MapEntry(K key, V value, Key valueKey) {
this.key = key;
this.value = value;
this.valueKey = valueKey;
}
public Key getValueKey() {
return valueKey;
}
public K getKey() {
return key;
}
public V getValue() {
return value;
}
public V setValue(V value) {
throw new UnsupportedOperationException();
}
@Override public boolean equals(Object obj) {
return obj instanceof Map.Entry
&& key.equals(((Map.Entry) obj).getKey())
&& value.equals(((Map.Entry) obj).getValue());
}
@Override public int hashCode() {
return 127 * ("key".hashCode() ^ key.hashCode())
+ 127 * ("value".hashCode() ^ value.hashCode());
}
@Override public String toString() {
return "MapEntry(" + key + ", " + value + ")";
}
}
private static abstract class RealMapWithExtensionProvider
extends RealMapBinderProviderWithDependencies
implements ProviderWithExtensionVisitor, MapBinderBinding {
public RealMapWithExtensionProvider(Object equality) {
super(equality);
}
}
/**
* A base class for ProviderWithDependencies that need equality
* based on a specific object.
*/
private static abstract class RealMapBinderProviderWithDependencies implements ProviderWithDependencies {
private final Object equality;
public RealMapBinderProviderWithDependencies(Object equality) {
this.equality = equality;
}
@Override
public boolean equals(Object obj) {
return this.getClass() == obj.getClass() &&
equality.equals(((RealMapBinderProviderWithDependencies)obj).equality);
}
}
}
}