com.hazelcast.jet.stream.impl.processor.GroupAndAccumulateP Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2018, Hazelcast, Inc. All Rights Reserved.
*
* 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.hazelcast.jet.stream.impl.processor;
import com.hazelcast.jet.core.AbstractProcessor;
import com.hazelcast.jet.Traverser;
import javax.annotation.Nonnull;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Function;
import java.util.stream.Collector;
import static com.hazelcast.jet.Traversers.lazy;
import static com.hazelcast.jet.Traversers.traverseStream;
import static com.hazelcast.jet.Util.entry;
public class GroupAndAccumulateP extends AbstractProcessor {
private final Map groups = new HashMap<>();
private final Function classifier;
private final Collector collector;
private final Traverser> resultTraverser;
public GroupAndAccumulateP(Function classifier, Collector collector) {
this.classifier = classifier;
this.collector = collector;
this.resultTraverser = lazy(() -> traverseStream(groups
.entrySet().stream()
.map(entry -> entry(entry.getKey(), entry.getValue()))
));
}
@Override
protected boolean tryProcess(int ordinal, @Nonnull Object item) throws Exception {
Map.Entry entry = entry(classifier.apply((T) item), (V) item);
A value = groups.computeIfAbsent(entry.getKey(), k -> collector.supplier().get());
collector.accumulator().accept(value, entry.getValue());
return true;
}
@Override
public boolean complete() {
return emitFromTraverser(resultTraverser);
}
}