wayang-platforms/wayang-flink/src/main/java/org/apache/wayang/flink/mapping/GroupByMapping.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.wayang.flink.mapping;

import java.util.Collection;
import java.util.Collections;
import org.apache.wayang.basic.operators.GroupByOperator;
import org.apache.wayang.core.function.FunctionDescriptor;
import org.apache.wayang.core.mapping.Mapping;
import org.apache.wayang.core.mapping.OperatorPattern;
import org.apache.wayang.core.mapping.PlanTransformation;
import org.apache.wayang.core.mapping.ReplacementSubplanFactory;
import org.apache.wayang.core.mapping.SubplanPattern;
import org.apache.wayang.flink.operators.FlinkGroupByOperator;
import org.apache.wayang.flink.platform.FlinkPlatform;

/**
 * Mapping from {@link GroupByOperator} to {@link FlinkGroupByOperator}.
 */
@SuppressWarnings("unchecked")
public class GroupByMapping implements Mapping{
    @Override
    public Collection<PlanTransformation> getTransformations() {
        return Collections.singleton(new PlanTransformation(
                this.createSubplanPattern(),
                this.createReplacementSubplanFactory(),
                FlinkPlatform.getInstance()
        ));
    }

    private SubplanPattern createSubplanPattern() {
        final OperatorPattern operatorPattern = new OperatorPattern(
                "groupby", new GroupByOperator<>((FunctionDescriptor.SerializableFunction)null, Void.class, Void.class), false);
        return SubplanPattern.createSingleton(operatorPattern);
    }


    private ReplacementSubplanFactory createReplacementSubplanFactory() {
        return new ReplacementSubplanFactory.OfSingleOperators<GroupByOperator>(
                (matchedOperator, epoch) -> new FlinkGroupByOperator<>(matchedOperator).at(epoch)
        );
    }
}