| /* |
| * 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.function.FunctionDescriptor; |
| import org.apache.wayang.core.function.TransformationDescriptor; |
| import org.apache.wayang.core.plan.wayangplan.UnaryToUnaryOperator; |
| import org.apache.wayang.core.types.DataSetType; |
| |
| /** |
| * This is the auxiliary GroupBy operator, i.e., it behaves differently depending on its context. If it is followed |
| * by a {@link ReduceOperator} (and akin), it turns that one into a {@link ReduceByOperator}. Otherwise, it corresponds to a |
| * {@link MaterializedGroupByOperator}. |
| * |
| * @see MaterializedGroupByOperator |
| * @see ReduceOperator |
| */ |
| public class GroupByOperator<Input, Key> extends UnaryToUnaryOperator<Input, Iterable<Input>> { |
| |
| protected final TransformationDescriptor<Input, Key> keyDescriptor; |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param keyFunction describes how to extract the key from data units |
| * @param typeClass class of the data quanta to be grouped |
| * @param keyClass class of the extracted keys |
| */ |
| public GroupByOperator(FunctionDescriptor.SerializableFunction<Input, Key> keyFunction, |
| Class<Input> typeClass, |
| Class<Key> keyClass) { |
| this(new TransformationDescriptor<>(keyFunction, typeClass, keyClass)); |
| } |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param keyDescriptor describes the key w.r.t. to the processed data units |
| */ |
| public GroupByOperator(TransformationDescriptor<Input, Key> keyDescriptor) { |
| this(keyDescriptor, |
| DataSetType.createDefault(keyDescriptor.getInputType()), |
| DataSetType.createGrouped(keyDescriptor.getInputType())); |
| } |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param keyDescriptor describes the key w.r.t. to the processed data units |
| * @param inputType class of the input types (i.e., type of {@link #getInput()} |
| * @param outputType class of the output types (i.e., type of {@link #getOutput()} |
| */ |
| public GroupByOperator(TransformationDescriptor<Input, Key> keyDescriptor, |
| DataSetType<Input> inputType, DataSetType<Iterable<Input>> outputType) { |
| super(inputType, outputType, false); |
| this.keyDescriptor = keyDescriptor; |
| } |
| |
| |
| public GroupByOperator(GroupByOperator<Input, Key> that){ |
| super(that); |
| this.keyDescriptor = that.keyDescriptor; |
| } |
| |
| public TransformationDescriptor<Input, Key> getKeyDescriptor() { |
| return this.keyDescriptor; |
| } |
| |
| |
| } |