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Lucene example source code file (FuzzyQueryNodeProcessor.java)

This example Lucene source code file (FuzzyQueryNodeProcessor.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

fuzzyattribute, fuzzyquerynode, fuzzyquerynode, fuzzyquerynodeprocessor, illegalargumentexception, no, override, override, queryconfighandler, querynode, querynode, querynodeexception, querynodeexception, querynodeprocessorimpl, util

The Lucene FuzzyQueryNodeProcessor.java source code

package org.apache.lucene.queryParser.standard.processors;

/**
 * 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.
 */

import java.util.List;

import org.apache.lucene.queryParser.core.QueryNodeException;
import org.apache.lucene.queryParser.core.config.QueryConfigHandler;
import org.apache.lucene.queryParser.core.nodes.FuzzyQueryNode;
import org.apache.lucene.queryParser.core.nodes.QueryNode;
import org.apache.lucene.queryParser.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryParser.standard.config.FuzzyAttribute;
import org.apache.lucene.search.FuzzyQuery;

/**
 * This processor iterates the query node tree looking for every
 * {@link FuzzyQueryNode}, when this kind of node is found, it checks on the
 * query configuration for {@link FuzzyAttribute}, gets the fuzzy prefix length
 * and default similarity from it and set to the fuzzy node. For more
 * information about fuzzy prefix length check: {@link FuzzyQuery}. <br/>
 * 
 * @see FuzzyAttribute
 * @see FuzzyQuery
 * @see FuzzyQueryNode
 */
public class FuzzyQueryNodeProcessor extends QueryNodeProcessorImpl {

  @Override
  protected QueryNode postProcessNode(QueryNode node) throws QueryNodeException {

    return node;

  }

  @Override
  protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {

    if (node instanceof FuzzyQueryNode) {
      FuzzyQueryNode fuzzyNode = (FuzzyQueryNode) node;
      QueryConfigHandler config = getQueryConfigHandler();

      if (config != null && config.hasAttribute(FuzzyAttribute.class)) {
        FuzzyAttribute fuzzyAttr = config.getAttribute(FuzzyAttribute.class);
        fuzzyNode.setPrefixLength(fuzzyAttr.getPrefixLength());

        if (fuzzyNode.getSimilarity() < 0) {
          fuzzyNode.setSimilarity(fuzzyAttr.getFuzzyMinSimilarity());

        }

      } else if (fuzzyNode.getSimilarity() < 0) {
        throw new IllegalArgumentException("No "
            + FuzzyAttribute.class.getName() + " set in the config");
      }

    }

    return node;

  }

  @Override
  protected List<QueryNode> setChildrenOrder(List children)
      throws QueryNodeException {

    return children;

  }

}

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