FieldsReader.cs :  » Search-Engines » dotLucene » Lucene » Net » Index » C# / CSharp Open Source

/*
 * Copyright 2004 The Apache Software Foundation
 * 
 * Licensed 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.
 */

using System;
using DocumentLucene.Net.Documents.Document;
using FieldLucene.Net.Documents.Field;
using DirectoryLucene.Net.Store.Directory;
using IndexInputLucene.Net.Store.IndexInput;

namespace Lucene.Net.Index{
  
  /// <summary> Class responsible for access to stored document fields.
  /// 
  /// It uses &lt;segment&gt;.fdt and &lt;segment&gt;.fdx; files.
  /// 
  /// </summary>
  /// <version>  $Id: FieldsReader.java 329524 2005-10-30 05:38:46Z yonik $
  /// </version>
  public sealed class FieldsReader
  {
    private FieldInfos fieldInfos;
    private IndexInput fieldsStream;
    private IndexInput indexStream;
    private int size;
    
    public /*internal*/ FieldsReader(Directory d, System.String segment, FieldInfos fn)
    {
      fieldInfos = fn;
      
      fieldsStream = d.OpenInput(segment + ".fdt");
      indexStream = d.OpenInput(segment + ".fdx");
      
      size = (int) (indexStream.Length() / 8);
    }
    
    public /*internal*/ void  Close()
    {
      fieldsStream.Close();
      indexStream.Close();
    }
    
    public /*internal*/ int Size()
    {
      return size;
    }
    
    public /*internal*/ Document Doc(int n)
    {
      indexStream.Seek(n * 8L);
      long position = indexStream.ReadLong();
      fieldsStream.Seek(position);
      
      Document doc = new Document();
      int numFields = fieldsStream.ReadVInt();
      for (int i = 0; i < numFields; i++)
      {
        int fieldNumber = fieldsStream.ReadVInt();
        FieldInfo fi = fieldInfos.FieldInfo(fieldNumber);
        
        byte bits = fieldsStream.ReadByte();
        
        bool compressed = (bits & FieldsWriter.FIELD_IS_COMPRESSED) != 0;
        bool tokenize = (bits & FieldsWriter.FIELD_IS_TOKENIZED) != 0;
        
        if ((bits & FieldsWriter.FIELD_IS_BINARY) != 0)
        {
          byte[] b = new byte[fieldsStream.ReadVInt()];
          fieldsStream.ReadBytes(b, 0, b.Length);
          if (compressed)
            doc.Add(new Field(fi.name, Uncompress(b), Field.Store.COMPRESS));
          else
            doc.Add(new Field(fi.name, b, Field.Store.YES));
        }
        else
        {
          Field.Index index;
          Field.Store store = Field.Store.YES;
          
          if (fi.isIndexed && tokenize)
            index = Field.Index.TOKENIZED;
          else if (fi.isIndexed && !tokenize)
            index = Field.Index.UN_TOKENIZED;
          else
            index = Field.Index.NO;
          
          Field.TermVector termVector = null;
          if (fi.storeTermVector)
          {
            if (fi.storeOffsetWithTermVector)
            {
              if (fi.storePositionWithTermVector)
              {
                termVector = Field.TermVector.WITH_POSITIONS_OFFSETS;
              }
              else
              {
                termVector = Field.TermVector.WITH_OFFSETS;
              }
            }
            else if (fi.storePositionWithTermVector)
            {
              termVector = Field.TermVector.WITH_POSITIONS;
            }
            else
            {
              termVector = Field.TermVector.YES;
            }
          }
          else
          {
            termVector = Field.TermVector.NO;
          }
          
          if (compressed)
          {
            store = Field.Store.COMPRESS;
            byte[] b = new byte[fieldsStream.ReadVInt()];
            fieldsStream.ReadBytes(b, 0, b.Length);
            Field f = new Field(fi.name, System.Text.Encoding.GetEncoding("UTF-8").GetString(Uncompress(b)), store, index, termVector);
            f.SetOmitNorms(fi.omitNorms);
            doc.Add(f);
          }
          else
          {
            Field f = new Field(fi.name, fieldsStream.ReadString(), store, index, termVector);
            f.SetOmitNorms(fi.omitNorms);
            doc.Add(f);
          }
        }
      }
      
      return doc;
    }
    
    private byte[] Uncompress(byte[] input)
    {
            // {{Aroush-1.9}} for .NET 1.1, we can use reflection and ZLib?
            return input;

            /*
      //UPGRADE_ISSUE: Class 'java.util.zip.Inflater' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javautilzipInflater'"
      //UPGRADE_ISSUE: Constructor 'java.util.zip.Inflater.Inflater' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javautilzipInflater'"
      Inflater decompressor = new Inflater();
      //UPGRADE_ISSUE: Method 'java.util.zip.Inflater.setInput' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javautilzipInflater'"
      decompressor.setInput(input);
      
      // Create an expandable byte array to hold the decompressed data
      System.IO.MemoryStream bos = new System.IO.MemoryStream(input.Length);
      
      // Decompress the data
      byte[] buf = new byte[1024];
      //UPGRADE_ISSUE: Method 'java.util.zip.Inflater.finished' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javautilzipInflater'"
      while (!decompressor.finished())
      {
        try
        {
          //UPGRADE_ISSUE: Method 'java.util.zip.Inflater.inflate' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javautilzipInflater'"
          int count = decompressor.inflate(buf);
          bos.Write(SupportClass.ToByteArray(buf), 0, count);
        }
        catch (Exception e)
        {
          // this will happen if the field is not compressed
          throw new System.IO.IOException("field data are in wrong format: " + e.ToString());
        }
      }
      
      //UPGRADE_ISSUE: Method 'java.util.zip.Inflater.end' was not converted. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1000_javautilzipInflater'"
      decompressor.end();
      
      // Get the decompressed data
      return SupportClass.ToSByteArray(bos.ToArray());
            */
    }
  }
}