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There is a newer version: 2024.11.18751.20241128T090041Z-241100
/*
 * 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.lucene42;

/*
 * 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.codecs.CodecUtil;
import org.apache.lucene.codecs.FieldInfosFormat;
import org.apache.lucene.codecs.FieldInfosReader;
import org.apache.lucene.codecs.FieldInfosWriter;
import org.apache.lucene.index.FieldInfo.DocValuesType; // javadoc
import org.apache.lucene.store.DataOutput; // javadoc

/**
 * Lucene 4.2 Field Infos format.
 * 
 * 
Field names are stored in the field info file, with suffix .fnm.
 * FieldInfos (.fnm) --> Header,FieldsCount, <FieldName,FieldNumber,
 * FieldBits,DocValuesBits,Attributes> ^FieldsCount
 * Data types:
 * 

 *   Header --> {@link CodecUtil#checkHeader CodecHeader}
 *   FieldsCount --> {@link DataOutput#writeVInt VInt}
 *   FieldName --> {@link DataOutput#writeString String}
 *   FieldBits, DocValuesBits --> {@link DataOutput#writeByte Byte}
 *   FieldNumber --> {@link DataOutput#writeInt VInt}
 *   Attributes --> {@link DataOutput#writeStringStringMap Map<String,String>}
 * 
 * 
 * Field Descriptions:
 * 
 *   FieldsCount: the number of fields in this file.
 *   FieldName: name of the field as a UTF-8 String.
 *   FieldNumber: the field's number. Note that unlike previous versions of
 *       Lucene, the fields are not numbered implicitly by their order in the
 *       file, instead explicitly.
 *   FieldBits: a byte containing field options.
 *       
 *         The low-order bit is one for indexed fields, and zero for non-indexed
 *             fields.
 *         The second lowest-order bit is one for fields that have term vectors
 *             stored, and zero for fields without term vectors.
 *         If the third lowest order-bit is set (0x4), offsets are stored into
 *             the postings list in addition to positions.
 *         Fourth bit is unused.
 *         If the fifth lowest-order bit is set (0x10), norms are omitted for the
 *             indexed field.
 *         If the sixth lowest-order bit is set (0x20), payloads are stored for the
 *             indexed field.
 *         If the seventh lowest-order bit is set (0x40), term frequencies and
 *             positions omitted for the indexed field.
 *         If the eighth lowest-order bit is set (0x80), positions are omitted for the
 *             indexed field.
 *       
 *    
 *    DocValuesBits: a byte containing per-document value types. The type
 *        recorded as two four-bit integers, with the high-order bits representing
 *        norms options, and the low-order bits representing 
 *        {@code DocValues} options. Each four-bit integer can be decoded as such:
 *        
 *          0: no DocValues for this field.
 *          1: NumericDocValues. ({@link DocValuesType#NUMERIC})
 *          2: BinaryDocValues. ({@code DocValuesType#BINARY})
 *          3: SortedDocValues. ({@code DocValuesType#SORTED})
 *        
 *    
 *    Attributes: a key-value map of codec-private attributes.
 * 
 *
 * @lucene.experimental
 * @deprecated Only for reading old 4.2-4.5 segments
 */
@Deprecated
public class Lucene42FieldInfosFormat extends FieldInfosFormat {
  private final FieldInfosReader reader = new Lucene42FieldInfosReader();
  
  /** Sole constructor. */
  public Lucene42FieldInfosFormat() {
  }

  @Override
  public FieldInfosReader getFieldInfosReader() throws IOException {
    return reader;
  }

  @Override
  public FieldInfosWriter getFieldInfosWriter() throws IOException {
    throw new UnsupportedOperationException("this codec can only be used for reading");
  }
  
  /** Extension of field infos */
  static final String EXTENSION = "fnm";
  
  // Codec header
  static final String CODEC_NAME = "Lucene42FieldInfos";
  static final int FORMAT_START = 0;
  static final int FORMAT_CURRENT = FORMAT_START;
  
  // Field flags
  static final byte IS_INDEXED = 0x1;
  static final byte STORE_TERMVECTOR = 0x2;
  static final byte STORE_OFFSETS_IN_POSTINGS = 0x4;
  static final byte OMIT_NORMS = 0x10;
  static final byte STORE_PAYLOADS = 0x20;
  static final byte OMIT_TERM_FREQ_AND_POSITIONS = 0x40;
  static final byte OMIT_POSITIONS = -128;
}