Lucene example source code file (MultipleTermPositions.java)

This example Lucene source code file (MultipleTermPositions.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

intqueue, io, ioexception, ioexception, linkedlist, multipletermpositions, override, priorityqueue, term, termpositions, termpositions, termpositionsqueue, termpositionsqueue, unsupportedoperationexception, unsupportedoperationexception, util

The Lucene MultipleTermPositions.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 java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

import org.apache.lucene.util.PriorityQueue;
import org.apache.lucene.util.ArrayUtil;

/**
 * Allows you to iterate over the {@link TermPositions} for multiple {@link Term}s as
 * a single {@link TermPositions}.
 *
 */
public class MultipleTermPositions implements TermPositions {

  private static final class TermPositionsQueue extends PriorityQueue<TermPositions> {
    TermPositionsQueue(List<TermPositions> termPositions) throws IOException {
      initialize(termPositions.size());

      for (TermPositions tp : termPositions) {
        if (tp.next())
          add(tp);
      }
    }

    final TermPositions peek() {
      return top();
    }

    @Override
    public final boolean lessThan(TermPositions a, TermPositions b) {
      return a.doc() < b.doc();
    }
  }

  private static final class IntQueue {
    private int _arraySize = 16;
    private int _index = 0;
    private int _lastIndex = 0;
    private int[] _array = new int[_arraySize];

    final void add(int i) {
      if (_lastIndex == _arraySize)
        growArray();

      _array[_lastIndex++] = i;
    }

    final int next() {
      return _array[_index++];
    }

    final void sort() {
      Arrays.sort(_array, _index, _lastIndex);
    }

    final void clear() {
      _index = 0;
      _lastIndex = 0;
    }

    final int size() {
      return (_lastIndex - _index);
    }

    private void growArray() {
      _array = ArrayUtil.grow(_array, _arraySize+1);
      _arraySize = _array.length;
    }
  }

  private int _doc;
  private int _freq;
  private TermPositionsQueue _termPositionsQueue;
  private IntQueue _posList;

  /**
   * Creates a new <code>MultipleTermPositions instance.
   * 
   * @exception IOException
   */
  public MultipleTermPositions(IndexReader indexReader, Term[] terms) throws IOException {
    List<TermPositions> termPositions = new LinkedList();

    for (int i = 0; i < terms.length; i++)
      termPositions.add(indexReader.termPositions(terms[i]));

    _termPositionsQueue = new TermPositionsQueue(termPositions);
    _posList = new IntQueue();
  }

  public final boolean next() throws IOException {
    if (_termPositionsQueue.size() == 0)
      return false;

    _posList.clear();
    _doc = _termPositionsQueue.peek().doc();

    TermPositions tp;
    do {
      tp = _termPositionsQueue.peek();

      for (int i = 0; i < tp.freq(); i++) {
        // NOTE: this can result in dup positions being added!
        _posList.add(tp.nextPosition());
      }

      if (tp.next())
        _termPositionsQueue.updateTop();
      else {
        _termPositionsQueue.pop();
        tp.close();
      }
    } while (_termPositionsQueue.size() > 0 && _termPositionsQueue.peek().doc() == _doc);

    _posList.sort();
    _freq = _posList.size();

    return true;
  }

  public final int nextPosition() {
    // NOTE: this may return the same position more than
    // once (see TestMultiPhraseQuery.testZeroPosIncr)
    return _posList.next();
  }

  public final boolean skipTo(int target) throws IOException {
    while (_termPositionsQueue.peek() != null && target > _termPositionsQueue.peek().doc()) {
      TermPositions tp =  _termPositionsQueue.pop();
      if (tp.skipTo(target))
        _termPositionsQueue.add(tp);
      else
        tp.close();
    }
    return next();
  }

  public final int doc() {
    return _doc;
  }

  public final int freq() {
    return _freq;
  }

  public final void close() throws IOException {
    while (_termPositionsQueue.size() > 0)
      _termPositionsQueue.pop().close();
  }

  /**
   * Not implemented.
   * @throws UnsupportedOperationException
   */
  public void seek(Term arg0) throws IOException {
    throw new UnsupportedOperationException();
  }

  /**
   * Not implemented.
   * @throws UnsupportedOperationException
   */
  public void seek(TermEnum termEnum) throws IOException {
    throw new UnsupportedOperationException();
  }

  /**
   * Not implemented.
   * @throws UnsupportedOperationException
   */
  public int read(int[] arg0, int[] arg1) throws IOException {
    throw new UnsupportedOperationException();
  }
  
  
  /**
   * Not implemented.
   * @throws UnsupportedOperationException
   */
  public int getPayloadLength() {
    throw new UnsupportedOperationException();
  }
   
  /**
   * Not implemented.
   * @throws UnsupportedOperationException
   */
  public byte[] getPayload(byte[] data, int offset) throws IOException {
    throw new UnsupportedOperationException();
  }

  /**
   *
   * @return false
   */
  // TODO: Remove warning after API has been finalized
  public boolean isPayloadAvailable() {
    return false;
  }
}