| /* |
| * 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.solr.client.solrj.io.ops; |
| |
| import java.io.IOException; |
| import java.util.UUID; |
| |
| import org.apache.solr.client.solrj.io.Tuple; |
| import org.apache.solr.client.solrj.io.stream.expr.Explanation; |
| import org.apache.solr.client.solrj.io.stream.expr.Explanation.ExpressionType; |
| import org.apache.solr.client.solrj.io.stream.expr.StreamExpression; |
| import org.apache.solr.client.solrj.io.stream.expr.StreamExpressionParameter; |
| import org.apache.solr.client.solrj.io.stream.expr.StreamFactory; |
| |
| public class DistinctOperation implements ReduceOperation { |
| |
| private static final long serialVersionUID = 1L; |
| private UUID operationNodeId = UUID.randomUUID(); |
| private Tuple current; |
| |
| public DistinctOperation(StreamExpression expression, StreamFactory factory) throws IOException { |
| init(); |
| } |
| |
| public DistinctOperation() { |
| init(); |
| } |
| |
| private void init() { |
| } |
| |
| public StreamExpressionParameter toExpression(StreamFactory factory) throws IOException { |
| StreamExpression expression = new StreamExpression(factory.getFunctionName(this.getClass())); |
| return expression; |
| } |
| |
| @Override |
| public Explanation toExplanation(StreamFactory factory) throws IOException { |
| return new Explanation(operationNodeId.toString()) |
| .withExpressionType(ExpressionType.OPERATION) |
| .withFunctionName(factory.getFunctionName(getClass())) |
| .withImplementingClass(getClass().getName()) |
| .withExpression(toExpression(factory).toString()); |
| } |
| |
| public Tuple reduce() { |
| // Return the tuple after setting current to null. This will ensure the next call to |
| // operate stores that tuple |
| Tuple toReturn = current; |
| current = null; |
| |
| return toReturn; |
| } |
| |
| public void operate(Tuple tuple) { |
| // we only care about the first one seen. Drop all but the first |
| if(null == current){ |
| current = tuple; |
| } |
| } |
| } |