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/*
* Copyright (C) 2016 The Dagger Authors.
*
* 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 dagger.producers.internal;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import dagger.producers.Producer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import javax.inject.Provider;
/**
* A {@link Producer} implementation used to implement {@link Map} bindings. This producer returns a
* {@code Map<K, V>} which is populated by calls to the delegate {@link Producer#get} methods.
*/
public final class MapProducer<K, V> extends AbstractMapProducer<K, V, V> {
private MapProducer(ImmutableMap<K, Producer<V>> contributingMap) {
super(contributingMap);
}
/** Returns a new {@link Builder}. */
public static <K, V> Builder<K, V> builder(int size) {
return new Builder<>(size);
}
/** A builder for {@link MapProducer} */
public static final class Builder<K, V> extends AbstractMapProducer.Builder<K, V, V> {
private Builder(int size) {
super(size);
}
@Override
public Builder<K, V> put(K key, Producer<V> producerOfValue) {
super.put(key, producerOfValue);
return this;
}
@Override
public Builder<K, V> put(K key, Provider<V> providerOfValue) {
super.put(key, providerOfValue);
return this;
}
@Override
public Builder<K, V> putAll(Producer<Map<K, V>> mapProducer) {
super.putAll(mapProducer);
return this;
}
/** Returns a new {@link MapProducer}. */
public MapProducer<K, V> build() {
return new MapProducer<>(mapBuilder.build());
}
}
@Override
protected ListenableFuture<Map<K, V>> compute() {
final List<ListenableFuture<Map.Entry<K, V>>> listOfEntries = new ArrayList<>();
for (final Entry<K, Producer<V>> entry : contributingMap().entrySet()) {
listOfEntries.add(
Futures.transform(
entry.getValue().get(),
new Function<V, Entry<K, V>>() {
@Override
public Entry<K, V> apply(V computedValue) {
return Maps.immutableEntry(entry.getKey(), computedValue);
}
},
directExecutor()));
}
return Futures.transform(
Futures.allAsList(listOfEntries),
new Function<List<Map.Entry<K, V>>, Map<K, V>>() {
@Override
public Map<K, V> apply(List<Map.Entry<K, V>> entries) {
return ImmutableMap.copyOf(entries);
}
},
directExecutor());
}
}