| /* |
| * 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.basic.operators; |
| |
| import org.apache.wayang.core.api.Configuration; |
| import org.apache.wayang.core.function.FunctionDescriptor; |
| import org.apache.wayang.core.function.ReduceDescriptor; |
| import org.apache.wayang.core.optimizer.cardinality.CardinalityEstimator; |
| import org.apache.wayang.core.optimizer.cardinality.FixedSizeCardinalityEstimator; |
| import org.apache.wayang.core.plan.wayangplan.UnaryToUnaryOperator; |
| import org.apache.wayang.core.types.DataSetType; |
| |
| import java.util.Optional; |
| |
| /** |
| * This operator is context dependent: after a {@link GroupByOperator}, it is meant to be a {@link ReduceByOperator}; |
| * otherwise, it is a {@link GlobalReduceOperator}. |
| */ |
| public class ReduceOperator<Type> extends UnaryToUnaryOperator<Type, Type> { |
| |
| private final ReduceDescriptor<Type> reduceDescriptor; |
| |
| /** |
| * @deprecated This method is just a hack that is necessary because of the ambiguous nature of this operator. |
| */ |
| public static <Type> ReduceOperator<Type> createGroupedReduce( |
| ReduceDescriptor<Type> reduceDescriptor, |
| DataSetType<? extends Iterable<Type>> inputType, |
| DataSetType<Type> outputType) { |
| return new ReduceOperator<>(reduceDescriptor, (DataSetType<Type>) inputType, outputType); |
| } |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param reduceDescriptor describes the reduction to be performed by this operator |
| */ |
| public ReduceOperator(ReduceDescriptor<Type> reduceDescriptor, |
| DataSetType<Type> inputType, DataSetType<Type> outputType) { |
| super(inputType, outputType, true); |
| this.reduceDescriptor = reduceDescriptor; |
| } |
| |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param reduceDescriptor describes the reduction to be performed by this operator |
| */ |
| public ReduceOperator(FunctionDescriptor.SerializableBinaryOperator<Type> reduceDescriptor, |
| Class<Type> typeClass) { |
| this(new ReduceDescriptor<>(reduceDescriptor, typeClass), |
| DataSetType.createDefault(typeClass), |
| DataSetType.createDefault(typeClass)); |
| } |
| |
| |
| |
| |
| public ReduceDescriptor<Type> getReduceDescriptor() { |
| return this.reduceDescriptor; |
| } |
| |
| @Override |
| public Optional<CardinalityEstimator> createCardinalityEstimator(int outputIndex, |
| Configuration configuration) { |
| return Optional.of(new FixedSizeCardinalityEstimator(1L)); |
| } |
| } |