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Lucene example source code file (WeightedSpanTermExtractor.java)

This example Lucene source code file (WeightedSpanTermExtractor.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

indexreader, io, ioexception, ioexception, list, map, map, set, spannearquery, spanquery, spanquery, string, term, util, weightedspanterm, weightedspanterm

The Lucene WeightedSpanTermExtractor.java source code

package org.apache.lucene.search.highlight;

/**
 * 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.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.lucene.analysis.CachingTokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.index.FilterIndexReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.memory.MemoryIndex;
import org.apache.lucene.search.*;
import org.apache.lucene.search.spans.FieldMaskingSpanQuery;
import org.apache.lucene.search.spans.SpanFirstQuery;
import org.apache.lucene.search.spans.SpanNearQuery;
import org.apache.lucene.search.spans.SpanNotQuery;
import org.apache.lucene.search.spans.SpanOrQuery;
import org.apache.lucene.search.spans.SpanQuery;
import org.apache.lucene.search.spans.SpanTermQuery;
import org.apache.lucene.search.spans.Spans;
import org.apache.lucene.util.StringHelper;

/**
 * Class used to extract {@link WeightedSpanTerm}s from a {@link Query} based on whether 
 * {@link Term}s from the {@link Query} are contained in a supplied {@link TokenStream}.
 */
public class WeightedSpanTermExtractor {

  private String fieldName;
  private TokenStream tokenStream;
  private Map<String,IndexReader> readers = new HashMap(10); 
  private String defaultField;
  private boolean expandMultiTermQuery;
  private boolean cachedTokenStream;
  private boolean wrapToCaching = true;
  private int maxDocCharsToAnalyze;

  public WeightedSpanTermExtractor() {
  }

  public WeightedSpanTermExtractor(String defaultField) {
    if (defaultField != null) {
      this.defaultField = StringHelper.intern(defaultField);
    }
  }

  private void closeReaders() {
    Collection<IndexReader> readerSet = readers.values();

    for (final IndexReader reader : readerSet) {
      try {
        reader.close();
      } catch (IOException e) {
        // alert?
      }
    }
  }

  /**
   * Fills a <code>Map with <@link WeightedSpanTerm>s using the terms from the supplied Query.
   * 
   * @param query
   *          Query to extract Terms from
   * @param terms
   *          Map to place created WeightedSpanTerms in
   * @throws IOException
   */
  private void extract(Query query, Map<String,WeightedSpanTerm> terms) throws IOException {
    if (query instanceof BooleanQuery) {
      BooleanClause[] queryClauses = ((BooleanQuery) query).getClauses();

      for (int i = 0; i < queryClauses.length; i++) {
        if (!queryClauses[i].isProhibited()) {
          extract(queryClauses[i].getQuery(), terms);
        }
      }
    } else if (query instanceof PhraseQuery) {
      PhraseQuery phraseQuery = ((PhraseQuery) query);
      Term[] phraseQueryTerms = phraseQuery.getTerms();
      SpanQuery[] clauses = new SpanQuery[phraseQueryTerms.length];
      for (int i = 0; i < phraseQueryTerms.length; i++) {
        clauses[i] = new SpanTermQuery(phraseQueryTerms[i]);
      }
      int slop = phraseQuery.getSlop();
      int[] positions = phraseQuery.getPositions();
      // add largest position increment to slop
      if (positions.length > 0) {
        int lastPos = positions[0];
        int largestInc = 0;
        int sz = positions.length;
        for (int i = 1; i < sz; i++) {
          int pos = positions[i];
          int inc = pos - lastPos;
          if (inc > largestInc) {
            largestInc = inc;
          }
          lastPos = pos;
        }
        if(largestInc > 1) {
          slop += largestInc;
        }
      }

      boolean inorder = false;

      if (slop == 0) {
        inorder = true;
      }

      SpanNearQuery sp = new SpanNearQuery(clauses, slop, inorder);
      sp.setBoost(query.getBoost());
      extractWeightedSpanTerms(terms, sp);
    } else if (query instanceof TermQuery) {
      extractWeightedTerms(terms, query);
    } else if (query instanceof SpanQuery) {
      extractWeightedSpanTerms(terms, (SpanQuery) query);
    } else if (query instanceof FilteredQuery) {
      extract(((FilteredQuery) query).getQuery(), terms);
    } else if (query instanceof DisjunctionMaxQuery) {
      for (Iterator<Query> iterator = ((DisjunctionMaxQuery) query).iterator(); iterator.hasNext();) {
        extract(iterator.next(), terms);
      }
    } else if (query instanceof MultiTermQuery && expandMultiTermQuery) {
      MultiTermQuery mtq = ((MultiTermQuery)query);
      if(mtq.getRewriteMethod() != MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE) {
        mtq = (MultiTermQuery) mtq.clone();
        mtq.setRewriteMethod(MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE);
        query = mtq;
      }
      FakeReader fReader = new FakeReader();
      MultiTermQuery.SCORING_BOOLEAN_QUERY_REWRITE.rewrite(fReader, mtq);
      if (fReader.field != null) {
        IndexReader ir = getReaderForField(fReader.field);
        extract(query.rewrite(ir), terms);
      }
    } else if (query instanceof MultiPhraseQuery) {
      final MultiPhraseQuery mpq = (MultiPhraseQuery) query;
      final List<Term[]> termArrays = mpq.getTermArrays();
      final int[] positions = mpq.getPositions();
      if (positions.length > 0) {

        int maxPosition = positions[positions.length - 1];
        for (int i = 0; i < positions.length - 1; ++i) {
          if (positions[i] > maxPosition) {
            maxPosition = positions[i];
          }
        }

        @SuppressWarnings("unchecked")
        final List<SpanQuery>[] disjunctLists = new List[maxPosition + 1];
        int distinctPositions = 0;

        for (int i = 0; i < termArrays.size(); ++i) {
          final Term[] termArray = termArrays.get(i);
          List<SpanQuery> disjuncts = disjunctLists[positions[i]];
          if (disjuncts == null) {
            disjuncts = (disjunctLists[positions[i]] = new ArrayList<SpanQuery>(termArray.length));
            ++distinctPositions;
          }
          for (int j = 0; j < termArray.length; ++j) {
            disjuncts.add(new SpanTermQuery(termArray[j]));
          }
        }

        int positionGaps = 0;
        int position = 0;
        final SpanQuery[] clauses = new SpanQuery[distinctPositions];
        for (int i = 0; i < disjunctLists.length; ++i) {
          List<SpanQuery> disjuncts = disjunctLists[i];
          if (disjuncts != null) {
            clauses[position++] = new SpanOrQuery(disjuncts
                .toArray(new SpanQuery[disjuncts.size()]));
          } else {
            ++positionGaps;
          }
        }

        final int slop = mpq.getSlop();
        final boolean inorder = (slop == 0);

        SpanNearQuery sp = new SpanNearQuery(clauses, slop + positionGaps, inorder);
        sp.setBoost(query.getBoost());
        extractWeightedSpanTerms(terms, sp);
      }
    }
  }

  /**
   * Fills a <code>Map with <@link WeightedSpanTerm>s using the terms from the supplied SpanQuery.
   * 
   * @param terms
   *          Map to place created WeightedSpanTerms in
   * @param spanQuery
   *          SpanQuery to extract Terms from
   * @throws IOException
   */
  private void extractWeightedSpanTerms(Map<String,WeightedSpanTerm> terms, SpanQuery spanQuery) throws IOException {
    Set<String> fieldNames;

    if (fieldName == null) {
      fieldNames = new HashSet<String>();
      collectSpanQueryFields(spanQuery, fieldNames);
    } else {
      fieldNames = new HashSet<String>(1);
      fieldNames.add(fieldName);
    }
    // To support the use of the default field name
    if (defaultField != null) {
      fieldNames.add(defaultField);
    }
    
    Map<String, SpanQuery> queries = new HashMap();
 
    Set<Term> nonWeightedTerms = new HashSet();
    final boolean mustRewriteQuery = mustRewriteQuery(spanQuery);
    if (mustRewriteQuery) {
      for (final String field : fieldNames) {
        final SpanQuery rewrittenQuery = (SpanQuery) spanQuery.rewrite(getReaderForField(field));
        queries.put(field, rewrittenQuery);
        rewrittenQuery.extractTerms(nonWeightedTerms);
      }
    } else {
      spanQuery.extractTerms(nonWeightedTerms);
    }

    List<PositionSpan> spanPositions = new ArrayList();

    for (final String field : fieldNames) {

      IndexReader reader = getReaderForField(field);
      final Spans spans;
      if (mustRewriteQuery) {
        spans = queries.get(field).getSpans(reader);
      } else {
        spans = spanQuery.getSpans(reader);
      }


      // collect span positions
      while (spans.next()) {
        spanPositions.add(new PositionSpan(spans.start(), spans.end() - 1));
      }
      
    }

    if (spanPositions.size() == 0) {
      // no spans found
      return;
    }

    for (final Term queryTerm :  nonWeightedTerms) {

      if (fieldNameComparator(queryTerm.field())) {
        WeightedSpanTerm weightedSpanTerm = terms.get(queryTerm.text());

        if (weightedSpanTerm == null) {
          weightedSpanTerm = new WeightedSpanTerm(spanQuery.getBoost(), queryTerm.text());
          weightedSpanTerm.addPositionSpans(spanPositions);
          weightedSpanTerm.positionSensitive = true;
          terms.put(queryTerm.text(), weightedSpanTerm);
        } else {
          if (spanPositions.size() > 0) {
            weightedSpanTerm.addPositionSpans(spanPositions);
          }
        }
      }
    }
  }

  /**
   * Fills a <code>Map with <@link WeightedSpanTerm>s using the terms from the supplied Query.
   * 
   * @param terms
   *          Map to place created WeightedSpanTerms in
   * @param query
   *          Query to extract Terms from
   * @throws IOException
   */
  private void extractWeightedTerms(Map<String,WeightedSpanTerm> terms, Query query) throws IOException {
    Set<Term> nonWeightedTerms = new HashSet();
    query.extractTerms(nonWeightedTerms);

    for (final Term queryTerm : nonWeightedTerms) {

      if (fieldNameComparator(queryTerm.field())) {
        WeightedSpanTerm weightedSpanTerm = new WeightedSpanTerm(query.getBoost(), queryTerm.text());
        terms.put(queryTerm.text(), weightedSpanTerm);
      }
    }
  }

  /**
   * Necessary to implement matches for queries against <code>defaultField
   */
  private boolean fieldNameComparator(String fieldNameToCheck) {
    boolean rv = fieldName == null || fieldNameToCheck == fieldName
        || fieldNameToCheck == defaultField;
    return rv;
  }

  private IndexReader getReaderForField(String field) throws IOException {
    if(wrapToCaching && !cachedTokenStream && !(tokenStream instanceof CachingTokenFilter)) {
      tokenStream = new CachingTokenFilter(new OffsetLimitTokenFilter(tokenStream, maxDocCharsToAnalyze));
      cachedTokenStream = true;
    }
    IndexReader reader = readers.get(field);
    if (reader == null) {
      MemoryIndex indexer = new MemoryIndex();
      indexer.addField(field, new OffsetLimitTokenFilter(tokenStream, maxDocCharsToAnalyze));
      tokenStream.reset();
      IndexSearcher searcher = indexer.createSearcher();
      reader = searcher.getIndexReader();
      readers.put(field, reader);
    }

    return reader;
  }

  /**
   * Creates a Map of <code>WeightedSpanTerms from the given Query and TokenStream.
   * 
   * <p>
   * 
   * @param query
   *          that caused hit
   * @param tokenStream
   *          of text to be highlighted
   * @return Map containing WeightedSpanTerms
   * @throws IOException
   */
  public Map<String,WeightedSpanTerm> getWeightedSpanTerms(Query query, TokenStream tokenStream)
      throws IOException {
    return getWeightedSpanTerms(query, tokenStream, null);
  }

  /**
   * Creates a Map of <code>WeightedSpanTerms from the given Query and TokenStream.
   * 
   * <p>
   * 
   * @param query
   *          that caused hit
   * @param tokenStream
   *          of text to be highlighted
   * @param fieldName
   *          restricts Term's used based on field name
   * @return Map containing WeightedSpanTerms
   * @throws IOException
   */
  public Map<String,WeightedSpanTerm> getWeightedSpanTerms(Query query, TokenStream tokenStream,
      String fieldName) throws IOException {
    if (fieldName != null) {
      this.fieldName = StringHelper.intern(fieldName);
    } else {
      this.fieldName = null;
    }

    Map<String,WeightedSpanTerm> terms = new PositionCheckingMap();
    this.tokenStream = tokenStream;
    try {
      extract(query, terms);
    } finally {
      closeReaders();
    }

    return terms;
  }

  /**
   * Creates a Map of <code>WeightedSpanTerms from the given Query and TokenStream. Uses a supplied
   * <code>IndexReader to properly weight terms (for gradient highlighting).
   * 
   * <p>
   * 
   * @param query
   *          that caused hit
   * @param tokenStream
   *          of text to be highlighted
   * @param fieldName
   *          restricts Term's used based on field name
   * @param reader
   *          to use for scoring
   * @return Map of WeightedSpanTerms with quasi tf/idf scores
   * @throws IOException
   */
  public Map<String,WeightedSpanTerm> getWeightedSpanTermsWithScores(Query query, TokenStream tokenStream, String fieldName,
      IndexReader reader) throws IOException {
    if (fieldName != null) {
      this.fieldName = StringHelper.intern(fieldName);
    } else {
      this.fieldName = null;
    }
    this.tokenStream = tokenStream;

    Map<String,WeightedSpanTerm> terms = new PositionCheckingMap();
    extract(query, terms);

    int totalNumDocs = reader.numDocs();
    Set<String> weightedTerms = terms.keySet();
    Iterator<String> it = weightedTerms.iterator();

    try {
      while (it.hasNext()) {
        WeightedSpanTerm weightedSpanTerm = terms.get(it.next());
        int docFreq = reader.docFreq(new Term(fieldName, weightedSpanTerm.term));
        // docFreq counts deletes
        if(totalNumDocs < docFreq) {
          docFreq = totalNumDocs;
        }
        // IDF algorithm taken from DefaultSimilarity class
        float idf = (float) (Math.log((float) totalNumDocs / (double) (docFreq + 1)) + 1.0);
        weightedSpanTerm.weight *= idf;
      }
    } finally {

      closeReaders();
    }

    return terms;
  }
  
  private void collectSpanQueryFields(SpanQuery spanQuery, Set<String> fieldNames) {
    if (spanQuery instanceof FieldMaskingSpanQuery) {
      collectSpanQueryFields(((FieldMaskingSpanQuery)spanQuery).getMaskedQuery(), fieldNames);
    } else if (spanQuery instanceof SpanFirstQuery) {
      collectSpanQueryFields(((SpanFirstQuery)spanQuery).getMatch(), fieldNames);
    } else if (spanQuery instanceof SpanNearQuery) {
      for (final SpanQuery clause : ((SpanNearQuery)spanQuery).getClauses()) {
        collectSpanQueryFields(clause, fieldNames);
      }
    } else if (spanQuery instanceof SpanNotQuery) {
      collectSpanQueryFields(((SpanNotQuery)spanQuery).getInclude(), fieldNames);
    } else if (spanQuery instanceof SpanOrQuery) {
      for (final SpanQuery clause : ((SpanOrQuery)spanQuery).getClauses()) {
        collectSpanQueryFields(clause, fieldNames);
      }
    } else {
      fieldNames.add(spanQuery.getField());
    }
  }
  
  private boolean mustRewriteQuery(SpanQuery spanQuery) {
    if (!expandMultiTermQuery) {
      return false; // Will throw UnsupportedOperationException in case of a SpanRegexQuery.
    } else if (spanQuery instanceof FieldMaskingSpanQuery) {
      return mustRewriteQuery(((FieldMaskingSpanQuery)spanQuery).getMaskedQuery());
    } else if (spanQuery instanceof SpanFirstQuery) {
      return mustRewriteQuery(((SpanFirstQuery)spanQuery).getMatch());
    } else if (spanQuery instanceof SpanNearQuery) {
      for (final SpanQuery clause : ((SpanNearQuery)spanQuery).getClauses()) {
        if (mustRewriteQuery(clause)) {
          return true;
        }
      }
      return false; 
    } else if (spanQuery instanceof SpanNotQuery) {
      SpanNotQuery spanNotQuery = (SpanNotQuery)spanQuery;
      return mustRewriteQuery(spanNotQuery.getInclude()) || mustRewriteQuery(spanNotQuery.getExclude());
    } else if (spanQuery instanceof SpanOrQuery) {
      for (final SpanQuery clause : ((SpanOrQuery)spanQuery).getClauses()) {
        if (mustRewriteQuery(clause)) {
          return true;
        }
      }
      return false; 
    } else if (spanQuery instanceof SpanTermQuery) {
      return false;
    } else {
      return true;
    }
  }
  
  /**
   * This class makes sure that if both position sensitive and insensitive
   * versions of the same term are added, the position insensitive one wins.
   */
  static private class PositionCheckingMap<K> extends HashMap {

    @Override
    public void putAll(Map<? extends K,? extends WeightedSpanTerm> m) {
      for (Map.Entry<? extends K,? extends WeightedSpanTerm> entry : m.entrySet())
        this.put(entry.getKey(), entry.getValue());
    }

    @Override
    public WeightedSpanTerm put(K key, WeightedSpanTerm value) {
      WeightedSpanTerm prev = super.put(key, value);
      if (prev == null) return prev;
      WeightedSpanTerm prevTerm = prev;
      WeightedSpanTerm newTerm = value;
      if (!prevTerm.positionSensitive) {
        newTerm.positionSensitive = false;
      }
      return prev;
    }
    
  }
  
  public boolean getExpandMultiTermQuery() {
    return expandMultiTermQuery;
  }

  public void setExpandMultiTermQuery(boolean expandMultiTermQuery) {
    this.expandMultiTermQuery = expandMultiTermQuery;
  }
  
  public boolean isCachedTokenStream() {
    return cachedTokenStream;
  }
  
  public TokenStream getTokenStream() {
    return tokenStream;
  }
  
  /**
   * By default, {@link TokenStream}s that are not of the type
   * {@link CachingTokenFilter} are wrapped in a {@link CachingTokenFilter} to
   * ensure an efficient reset - if you are already using a different caching
   * {@link TokenStream} impl and you don't want it to be wrapped, set this to
   * false.
   * 
   * @param wrap
   */
  public void setWrapIfNotCachingTokenFilter(boolean wrap) {
    this.wrapToCaching = wrap;
  }
  
  /**
   * 
   * A fake IndexReader class to extract the field from a MultiTermQuery
   * 
   */
  static final class FakeReader extends FilterIndexReader {

    private static final IndexReader EMPTY_MEMORY_INDEX_READER =
      new MemoryIndex().createSearcher().getIndexReader();
    
    String field;

    FakeReader() {
      super(EMPTY_MEMORY_INDEX_READER);
    }

    @Override
    public TermEnum terms(final Term t) throws IOException {
      // only set first fieldname, maybe use a Set?
      if (t != null && field == null)
        field = t.field();
      return super.terms(t);
    }


  }

  protected final void setMaxDocCharsToAnalyze(int maxDocCharsToAnalyze) {
    this.maxDocCharsToAnalyze = maxDocCharsToAnalyze;
  }

}

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