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 java.io.IOException;
import org.apache.lucene.codecs.CodecUtil;
import org.apache.lucene.codecs.StoredFieldsFormat;
import org.apache.lucene.codecs.StoredFieldsReader;
import org.apache.lucene.codecs.StoredFieldsWriter;
import org.apache.lucene.index.FieldInfos;
import org.apache.lucene.index.SegmentInfo;
import org.apache.lucene.store.DataOutput; // javadocs
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.IOContext;
/**
* Lucene 4.0 Stored Fields Format.
* <p>Stored fields are represented by two files:</p>
* <ol>
* <li><a name="field_index" id="field_index"></a>
* <p>The field index, or <tt>.fdx</tt> file.</p>
* <p>This is used to find the location within the field data file of the fields
* of a particular document. Because it contains fixed-length data, this file may
* be easily randomly accessed. The position of document <i>n</i> 's field data is
* the {@link DataOutput#writeLong Uint64} at <i>n*8</i> in this file.</p>
* <p>This contains, for each document, a pointer to its field data, as
* follows:</p>
* <ul>
* <li>FieldIndex (.fdx) --> <Header>, <FieldValuesPosition> <sup>SegSize</sup></li>
* <li>Header --> {@link CodecUtil#writeHeader CodecHeader}</li>
* <li>FieldValuesPosition --> {@link DataOutput#writeLong Uint64}</li>
* </ul>
* </li>
* <li>
* <p><a name="field_data" id="field_data"></a>The field data, or <tt>.fdt</tt> file.</p>
* <p>This contains the stored fields of each document, as follows:</p>
* <ul>
* <li>FieldData (.fdt) --> <Header>, <DocFieldData> <sup>SegSize</sup></li>
* <li>Header --> {@link CodecUtil#writeHeader CodecHeader}</li>
* <li>DocFieldData --> FieldCount, <FieldNum, Bits, Value>
* <sup>FieldCount</sup></li>
* <li>FieldCount --> {@link DataOutput#writeVInt VInt}</li>
* <li>FieldNum --> {@link DataOutput#writeVInt VInt}</li>
* <li>Bits --> {@link DataOutput#writeByte Byte}</li>
* <ul>
* <li>low order bit reserved.</li>
* <li>second bit is one for fields containing binary data</li>
* <li>third bit reserved.</li>
* <li>4th to 6th bit (mask: 0x7<<3) define the type of a numeric field:
* <ul>
* <li>all bits in mask are cleared if no numeric field at all</li>
* <li>1<<3: Value is Int</li>
* <li>2<<3: Value is Long</li>
* <li>3<<3: Value is Int as Float (as of {@link Float#intBitsToFloat(int)}</li>
* <li>4<<3: Value is Long as Double (as of {@link Double#longBitsToDouble(long)}</li>
* </ul>
* </li>
* </ul>
* <li>Value --> String | BinaryValue | Int | Long (depending on Bits)</li>
* <li>BinaryValue --> ValueSize, <{@link DataOutput#writeByte Byte}>^ValueSize</li>
* <li>ValueSize --> {@link DataOutput#writeVInt VInt}</li>
* </li>
* </ul>
* </ol>
* @lucene.experimental */
public class Lucene40StoredFieldsFormat extends StoredFieldsFormat {
/** Sole constructor. */
public Lucene40StoredFieldsFormat() {
}
@Override
public StoredFieldsReader fieldsReader(Directory directory, SegmentInfo si,
FieldInfos fn, IOContext context) throws IOException {
return new Lucene40StoredFieldsReader(directory, si, fn, context);
}
@Override
public StoredFieldsWriter fieldsWriter(Directory directory, SegmentInfo si,
IOContext context) throws IOException {
return new Lucene40StoredFieldsWriter(directory, si.name, context);
}
}