mirror of
https://github.com/reactos/reactos.git
synced 2024-08-03 18:10:54 +00:00
326 lines
9.7 KiB
C#
326 lines
9.7 KiB
C#
using System;
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using System.IO;
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using System.Collections;
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using System.Collections.Specialized;
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namespace HtmlHelp.ChmDecoding
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{
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/// <summary>
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/// The class <c>CHMBtree</c> implements methods/properties to decode the binary help index.
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/// This class automatically creates an index arraylist for the current CHMFile instance.
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/// It does not store the index internally !
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/// </summary>
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/// <remarks>The binary index can be found in the storage file $WWKeywordLinks/BTree</remarks>
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internal sealed class CHMBtree : IDisposable
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{
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/// <summary>
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/// Constant specifying the size of the string blocks
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/// </summary>
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private const int BLOCK_SIZE = 2048;
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/// <summary>
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/// Internal flag specifying if the object is going to be disposed
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/// </summary>
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private bool disposed = false;
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/// <summary>
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/// Internal member storing the binary file data
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/// </summary>
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private byte[] _binaryFileData = null;
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/// <summary>
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/// Internal member storing flags
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/// </summary>
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private int _flags = 0;
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/// <summary>
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/// Internal member storing the data format
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/// </summary>
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private byte[] _dataFormat = new byte[16];
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/// <summary>
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/// Internal member storing the index of the last listing block
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/// </summary>
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private int _indexOfLastListingBlock = 0;
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/// <summary>
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/// Internal member storing the index of the root block
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/// </summary>
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private int _indexOfRootBlock = 0;
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/// <summary>
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/// Internal member storing the number of blocks
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/// </summary>
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private int _numberOfBlocks = 0;
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/// <summary>
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/// Internal member storing the tree depth.
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/// (1 if no index blocks, 2 one level of index blocks, ...)
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/// </summary>
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private int _treeDepth = 0;
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/// <summary>
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/// Internal member storing the number of keywords in the file
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/// </summary>
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private int _numberOfKeywords = 0;
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/// <summary>
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/// Internal member storing the codepage
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/// </summary>
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private int _codePage = 0;
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/// <summary>
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/// true if the index is from a CHI or CHM file, else CHW
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/// </summary>
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private bool _isCHI_CHM = true;
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/// <summary>
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/// Internal member storing the associated chmfile object
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/// </summary>
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private CHMFile _associatedFile = null;
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/// <summary>
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/// Internal flag specifying if we have to read listing or index blocks
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/// </summary>
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private bool _readListingBlocks = true;
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/// <summary>
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/// Internal member storing an indexlist of the current file.
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/// </summary>
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private ArrayList _indexList = new ArrayList();
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/// <summary>
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/// Constructor of the class
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/// </summary>
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/// <param name="binaryFileData">binary file data of the $WWKeywordLinks/BTree file</param>
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/// <param name="associatedFile">associated chm file</param>
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public CHMBtree(byte[] binaryFileData, CHMFile associatedFile)
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{
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if( associatedFile == null)
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{
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throw new ArgumentException("CHMBtree.ctor() - Associated CHMFile must not be null !", "associatedFile");
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}
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_binaryFileData = binaryFileData;
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_associatedFile = associatedFile;
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DecodeData();
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// clear internal binary data after extraction
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_binaryFileData = null;
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}
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/// <summary>
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/// Decodes the binary file data and fills the internal properties
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/// </summary>
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/// <returns>true if succeeded</returns>
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private bool DecodeData()
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{
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bool bRet = true;
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MemoryStream memStream = new MemoryStream(_binaryFileData);
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BinaryReader binReader = new BinaryReader(memStream);
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int nCurOffset = 0;
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int nTemp = 0;
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// decode header
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binReader.ReadChars(2); // 2chars signature (not important)
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_flags = (int)binReader.ReadInt16(); // WORD flags
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binReader.ReadInt16(); // size of blocks (always 2048)
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_dataFormat = binReader.ReadBytes(16);
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binReader.ReadInt32(); // unknown DWORD
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_indexOfLastListingBlock = binReader.ReadInt32();
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_indexOfRootBlock = binReader.ReadInt32();
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binReader.ReadInt32(); // unknown DWORD
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_numberOfBlocks = binReader.ReadInt32();
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_treeDepth = binReader.ReadInt16();
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_numberOfKeywords = binReader.ReadInt32();
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_codePage = binReader.ReadInt32();
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binReader.ReadInt32(); // lcid DWORD
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nTemp = binReader.ReadInt32();
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_isCHI_CHM = (nTemp==1);
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binReader.ReadInt32(); // unknown DWORD
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binReader.ReadInt32(); // unknown DWORD
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binReader.ReadInt32(); // unknown DWORD
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binReader.ReadInt32(); // unknown DWORD
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// end of header decode
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while( (memStream.Position < memStream.Length) && (bRet) )
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{
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nCurOffset = (int)memStream.Position;
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byte [] dataBlock = binReader.ReadBytes(BLOCK_SIZE);
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bRet &= DecodeBlock(dataBlock, ref nCurOffset, _treeDepth-1);
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}
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return bRet;
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}
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/// <summary>
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/// Decodes a block of url-string data
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/// </summary>
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/// <param name="dataBlock">block of data</param>
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/// <param name="nOffset">current file offset</param>
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/// <param name="indexBlocks">number of index blocks</param>
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/// <returns>true if succeeded</returns>
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private bool DecodeBlock( byte[] dataBlock, ref int nOffset, int indexBlocks )
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{
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bool bRet = true;
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int nblockOffset = nOffset;
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MemoryStream memStream = new MemoryStream(dataBlock);
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BinaryReader binReader = new BinaryReader(memStream);
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int freeSpace = binReader.ReadInt16(); // length of freespace
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int nrOfEntries = binReader.ReadInt16(); // number of entries
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bool bListingEndReached = false;
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//while( (memStream.Position < (memStream.Length-freeSpace)) && (bRet) )
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//{
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int nIndexOfPrevBlock = -1;
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int nIndexOfNextBlock = -1;
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int nIndexOfChildBlock = 0;
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if(_readListingBlocks)
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{
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nIndexOfPrevBlock = binReader.ReadInt32(); // -1 if this is the header
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nIndexOfNextBlock = binReader.ReadInt32(); // -1 if this is the last block
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}
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else
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{
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nIndexOfChildBlock = binReader.ReadInt32();
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}
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for(int nE = 0; nE < nrOfEntries; nE++)
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{
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if(_readListingBlocks)
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{
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bListingEndReached = (nIndexOfNextBlock==-1);
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string keyWord = BinaryReaderHelp.ExtractUTF16String(ref binReader, 0, true, _associatedFile.TextEncoding);
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bool isSeeAlsoKeyword = (binReader.ReadInt16()!=0);
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int indent = binReader.ReadInt16(); // indent of entry
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int nCharIndex = binReader.ReadInt32();
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binReader.ReadInt32();
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int numberOfPairs = binReader.ReadInt32();
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int[] nTopics = new int[numberOfPairs];
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string[] seeAlso = new string[numberOfPairs];
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for(int i=0; i < numberOfPairs; i++)
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{
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if(isSeeAlsoKeyword)
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{
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seeAlso[i] = BinaryReaderHelp.ExtractUTF16String(ref binReader, 0, true, _associatedFile.TextEncoding);
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}
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else
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{
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nTopics[i] = binReader.ReadInt32();
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}
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}
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binReader.ReadInt32(); // unknown
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int nIndexOfThisEntry = binReader.ReadInt32();
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IndexItem newItem = new IndexItem(_associatedFile, keyWord, isSeeAlsoKeyword, indent, nCharIndex, nIndexOfThisEntry, seeAlso, nTopics);
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_indexList.Add(newItem);
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}
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else
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{
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string keyWord = BinaryReaderHelp.ExtractUTF16String(ref binReader, 0, true, _associatedFile.TextEncoding);
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bool isSeeAlsoKeyword = (binReader.ReadInt16()!=0);
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int indent = binReader.ReadInt16(); // indent of entry
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int nCharIndex = binReader.ReadInt32();
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binReader.ReadInt32();
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int numberOfPairs = binReader.ReadInt32();
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int[] nTopics = new int[numberOfPairs];
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string[] seeAlso = new string[numberOfPairs];
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for(int i=0; i < numberOfPairs; i++)
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{
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if(isSeeAlsoKeyword)
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{
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seeAlso[i] = BinaryReaderHelp.ExtractUTF16String(ref binReader, 0, true, _associatedFile.TextEncoding);
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}
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else
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{
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nTopics[i] = binReader.ReadInt32();
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}
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}
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int nIndexChild = binReader.ReadInt32();
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int nIndexOfThisEntry=-1;
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IndexItem newItem = new IndexItem(_associatedFile, keyWord, isSeeAlsoKeyword, indent, nCharIndex, nIndexOfThisEntry, seeAlso, nTopics);
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_indexList.Add(newItem);
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}
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}
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//}
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binReader.ReadBytes(freeSpace);
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if( bListingEndReached )
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_readListingBlocks = false;
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return bRet;
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}
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/// <summary>
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/// Gets the internal generated index list
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/// </summary>
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internal ArrayList IndexList
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{
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get { return _indexList; }
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}
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/// <summary>
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/// Implement IDisposable.
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/// </summary>
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public void Dispose()
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{
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Dispose(true);
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// This object will be cleaned up by the Dispose method.
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// Therefore, you should call GC.SupressFinalize to
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// take this object off the finalization queue
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// and prevent finalization code for this object
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// from executing a second time.
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GC.SuppressFinalize(this);
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}
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/// <summary>
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/// Dispose(bool disposing) executes in two distinct scenarios.
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/// If disposing equals true, the method has been called directly
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/// or indirectly by a user's code. Managed and unmanaged resources
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/// can be disposed.
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/// If disposing equals false, the method has been called by the
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/// runtime from inside the finalizer and you should not reference
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/// other objects. Only unmanaged resources can be disposed.
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/// </summary>
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/// <param name="disposing">disposing flag</param>
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private void Dispose(bool disposing)
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{
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// Check to see if Dispose has already been called.
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if(!this.disposed)
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{
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// If disposing equals true, dispose all managed
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// and unmanaged resources.
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if(disposing)
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{
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// Dispose managed resources.
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_binaryFileData = null;
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}
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}
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disposed = true;
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}
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}
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}
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