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Lucene example source code file (SegmentTermDocs.java)

This example Lucene source code file (SegmentTermDocs.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

bitvector, defaultskiplistreader, fieldinfo, indexinput, indexinput, io, ioexception, ioexception, segmenttermdocs, segmenttermenum, segmenttermenum, term, termdocs, terminfo, terminfo

The Lucene SegmentTermDocs.java source code

package org.apache.lucene.index;

/**
 * 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 org.apache.lucene.util.BitVector;
import org.apache.lucene.store.IndexInput;

class SegmentTermDocs implements TermDocs {
  protected SegmentReader parent;
  protected IndexInput freqStream;
  protected int count;
  protected int df;
  protected BitVector deletedDocs;
  int doc = 0;
  int freq;

  private int skipInterval;
  private int maxSkipLevels;
  private DefaultSkipListReader skipListReader;
  
  private long freqBasePointer;
  private long proxBasePointer;

  private long skipPointer;
  private boolean haveSkipped;
  
  protected boolean currentFieldStoresPayloads;
  protected boolean currentFieldOmitTermFreqAndPositions;
  
  protected SegmentTermDocs(SegmentReader parent) {
    this.parent = parent;
    this.freqStream = (IndexInput) parent.core.freqStream.clone();
    synchronized (parent) {
      this.deletedDocs = parent.deletedDocs;
    }
    this.skipInterval = parent.core.getTermsReader().getSkipInterval();
    this.maxSkipLevels = parent.core.getTermsReader().getMaxSkipLevels();
  }

  public void seek(Term term) throws IOException {
    TermInfo ti = parent.core.getTermsReader().get(term);
    seek(ti, term);
  }

  public void seek(TermEnum termEnum) throws IOException {
    TermInfo ti;
    Term term;
    
    // use comparison of fieldinfos to verify that termEnum belongs to the same segment as this SegmentTermDocs
    if (termEnum instanceof SegmentTermEnum && ((SegmentTermEnum) termEnum).fieldInfos == parent.core.fieldInfos) {        // optimized case
      SegmentTermEnum segmentTermEnum = ((SegmentTermEnum) termEnum);
      term = segmentTermEnum.term();
      ti = segmentTermEnum.termInfo();
    } else  {                                         // punt case
      term = termEnum.term();
      ti = parent.core.getTermsReader().get(term);
    }
    
    seek(ti, term);
  }

  void seek(TermInfo ti, Term term) throws IOException {
    count = 0;
    FieldInfo fi = parent.core.fieldInfos.fieldInfo(term.field);
    currentFieldOmitTermFreqAndPositions = (fi != null) ? fi.omitTermFreqAndPositions : false;
    currentFieldStoresPayloads = (fi != null) ? fi.storePayloads : false;
    if (ti == null) {
      df = 0;
    } else {
      df = ti.docFreq;
      doc = 0;
      freqBasePointer = ti.freqPointer;
      proxBasePointer = ti.proxPointer;
      skipPointer = freqBasePointer + ti.skipOffset;
      freqStream.seek(freqBasePointer);
      haveSkipped = false;
    }
  }

  public void close() throws IOException {
    freqStream.close();
    if (skipListReader != null)
      skipListReader.close();
  }

  public final int doc() { return doc; }
  public final int freq() { return freq; }

  protected void skippingDoc() throws IOException {
  }

  public boolean next() throws IOException {
    while (true) {
      if (count == df)
        return false;
      final int docCode = freqStream.readVInt();
      
      if (currentFieldOmitTermFreqAndPositions) {
        doc += docCode;
        freq = 1;
      } else {
        doc += docCode >>> 1;       // shift off low bit
        if ((docCode & 1) != 0)       // if low bit is set
          freq = 1;         // freq is one
        else
          freq = freqStream.readVInt();     // else read freq
      }
      
      count++;

      if (deletedDocs == null || !deletedDocs.get(doc))
        break;
      skippingDoc();
    }
    return true;
  }

  /** Optimized implementation. */
  public int read(final int[] docs, final int[] freqs)
          throws IOException {
    final int length = docs.length;
    if (currentFieldOmitTermFreqAndPositions) {
      return readNoTf(docs, freqs, length);
    } else {
      int i = 0;
      while (i < length && count < df) {
        // manually inlined call to next() for speed
        final int docCode = freqStream.readVInt();
        doc += docCode >>> 1;       // shift off low bit
        if ((docCode & 1) != 0)       // if low bit is set
          freq = 1;         // freq is one
        else
          freq = freqStream.readVInt();     // else read freq
        count++;

        if (deletedDocs == null || !deletedDocs.get(doc)) {
          docs[i] = doc;
          freqs[i] = freq;
          ++i;
        }
      }
      return i;
    }
  }

  private final int readNoTf(final int[] docs, final int[] freqs, final int length) throws IOException {
    int i = 0;
    while (i < length && count < df) {
      // manually inlined call to next() for speed
      doc += freqStream.readVInt();       
      count++;

      if (deletedDocs == null || !deletedDocs.get(doc)) {
        docs[i] = doc;
        // Hardware freq to 1 when term freqs were not
        // stored in the index
        freqs[i] = 1;
        ++i;
      }
    }
    return i;
  }
 
  
  /** Overridden by SegmentTermPositions to skip in prox stream. */
  protected void skipProx(long proxPointer, int payloadLength) throws IOException {}

  /** Optimized implementation. */
  public boolean skipTo(int target) throws IOException {
    if ((target - skipInterval) >= doc && df >= skipInterval) {                      // optimized case
      if (skipListReader == null)
        skipListReader = new DefaultSkipListReader((IndexInput) freqStream.clone(), maxSkipLevels, skipInterval); // lazily clone

      if (!haveSkipped) {                          // lazily initialize skip stream
        skipListReader.init(skipPointer, freqBasePointer, proxBasePointer, df, currentFieldStoresPayloads);
        haveSkipped = true;
      }

      int newCount = skipListReader.skipTo(target); 
      if (newCount > count) {
        freqStream.seek(skipListReader.getFreqPointer());
        skipProx(skipListReader.getProxPointer(), skipListReader.getPayloadLength());

        doc = skipListReader.getDoc();
        count = newCount;
      }      
    }

    // done skipping, now just scan
    do {
      if (!next())
        return false;
    } while (target > doc);
    return true;
  }
}

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