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/*
 * COPIED FROM APACHE LUCENE 4.7.2
 *
 * Git URL: [email protected]:apache/lucene.git, tag: releases/lucene-solr/4.7.2, path: lucene/core/src/java
 *
 * (see https://issues.apache.org/jira/browse/OAK-10786 for details)
 */

package org.apache.lucene.codecs.lucene40;

/*
 * 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 org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.codecs.SegmentInfoFormat;
import org.apache.lucene.codecs.SegmentInfoReader;
import org.apache.lucene.codecs.SegmentInfoWriter;
import org.apache.lucene.index.IndexWriter; // javadocs
import org.apache.lucene.index.SegmentInfo; // javadocs
import org.apache.lucene.index.SegmentInfos; // javadocs
import org.apache.lucene.store.DataOutput; // javadocs

/**
 * Lucene 4.0 Segment info format.
 * 
 * Files:
 * 

 *   .si: Header, SegVersion, SegSize, IsCompoundFile, Diagnostics, Attributes, Files
 * 
 * 
 * Data types:
 * 
 * 

 *   Header --> {@link CodecUtil#writeHeader CodecHeader}
 *   SegSize --> {@link DataOutput#writeInt Int32}
 *   SegVersion --> {@link DataOutput#writeString String}
 *   Files --> {@link DataOutput#writeStringSet Set<String>}
 *   Diagnostics, Attributes --> {@link DataOutput#writeStringStringMap Map<String,String>}
 *   IsCompoundFile --> {@link DataOutput#writeByte Int8}
 * 
 * 
 * Field Descriptions:
 * 
 * 

 *   SegVersion is the code version that created the segment.
 *   SegSize is the number of documents contained in the segment index.
 *   IsCompoundFile records whether the segment is written as a compound file or
 *       not. If this is -1, the segment is not a compound file. If it is 1, the segment
 *       is a compound file.
 *   Checksum contains the CRC32 checksum of all bytes in the segments_N file up
 *       until the checksum. This is used to verify integrity of the file on opening the
 *       index.
 *   The Diagnostics Map is privately written by {@link IndexWriter}, as a debugging aid,
 *       for each segment it creates. It includes metadata like the current Lucene
 *       version, OS, Java version, why the segment was created (merge, flush,
 *       addIndexes), etc.
 *   Attributes: a key-value map of codec-private attributes.
 *   Files is a list of files referred to by this segment.
 * 
 * 
 * 
 * @see SegmentInfos
 * @lucene.experimental
 * @deprecated Only for reading old 4.0-4.5 segments, and supporting IndexWriter.addIndexes
 */
@Deprecated
public class Lucene40SegmentInfoFormat extends SegmentInfoFormat {
  private final SegmentInfoReader reader = new Lucene40SegmentInfoReader();
  private final SegmentInfoWriter writer = new Lucene40SegmentInfoWriter();

  /** Sole constructor. */
  public Lucene40SegmentInfoFormat() {
  }
  
  @Override
  public SegmentInfoReader getSegmentInfoReader() {
    return reader;
  }

  // we must unfortunately support write, to allow addIndexes to write a new .si with rewritten filenames:
  // see LUCENE-5377
  @Override
  public SegmentInfoWriter getSegmentInfoWriter() {
    return writer;
  }

  /** File extension used to store {@link SegmentInfo}. */
  public final static String SI_EXTENSION = "si";
  static final String CODEC_NAME = "Lucene40SegmentInfo";
  static final int VERSION_START = 0;
  static final int VERSION_CURRENT = VERSION_START;
}