reactos/irc/TechBot/CHMLibrary/CHMDecoding/CHMStrings.cs

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C#
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using System;
using System.IO;
using System.Collections;
using System.Collections.Specialized;
namespace HtmlHelp.ChmDecoding
{
/// <summary>
/// The class <c>CHMStrings</c> implements a string collection read from the #STRINGS file
/// </summary>
internal sealed class CHMStrings : IDisposable
{
/// <summary>
/// Constant specifying the size of the string blocks
/// </summary>
private const int STRING_BLOCK_SIZE = 4096;
/// <summary>
/// Internal flag specifying if the object is going to be disposed
/// </summary>
private bool disposed = false;
/// <summary>
/// Internal member storing the binary file data
/// </summary>
private byte[] _binaryFileData = null;
/// <summary>
/// Internal member storing the string dictionary
/// </summary>
private Hashtable _stringDictionary = new Hashtable();
/// <summary>
/// Internal member storing the associated chmfile object
/// </summary>
private CHMFile _associatedFile = null;
/// <summary>
/// Constructor of the class
/// </summary>
/// <param name="binaryFileData">binary file data of the #STRINGS file</param>
/// <param name="associatedFile">associated chm file</param>
public CHMStrings(byte[] binaryFileData, CHMFile associatedFile)
{
_binaryFileData = binaryFileData;
_associatedFile = associatedFile;
DecodeData();
}
/// <summary>
/// Standard constructor
/// </summary>
internal CHMStrings()
{
}
#region Data dumping
/// <summary>
/// Dump the class data to a binary writer
/// </summary>
/// <param name="writer">writer to write the data</param>
internal void Dump(ref BinaryWriter writer)
{
writer.Write( _stringDictionary.Count );
if (_stringDictionary.Count != 0)
{
IDictionaryEnumerator iDictionaryEnumerator = _stringDictionary.GetEnumerator();
while (iDictionaryEnumerator.MoveNext())
{
DictionaryEntry dictionaryEntry = (DictionaryEntry)iDictionaryEnumerator.Current;
writer.Write( Int32.Parse(dictionaryEntry.Key.ToString()) );
writer.Write( dictionaryEntry.Value.ToString() );
}
}
}
/// <summary>
/// Reads the object data from a dump store
/// </summary>
/// <param name="reader">reader to read the data</param>
internal void ReadDump(ref BinaryReader reader)
{
int nCnt = reader.ReadInt32();
for(int i=0; i<nCnt;i++)
{
int nKey = reader.ReadInt32();
string sValue = reader.ReadString();
_stringDictionary[nKey.ToString()] = sValue;
}
}
/// <summary>
/// Sets the associated CHMFile instance
/// </summary>
/// <param name="associatedFile">instance to set</param>
internal void SetCHMFile(CHMFile associatedFile)
{
_associatedFile = associatedFile;
}
#endregion
/// <summary>
/// Decodes the binary file data and fills the internal properties
/// </summary>
/// <returns>true if succeeded</returns>
private bool DecodeData()
{
bool bRet = true;
MemoryStream memStream = new MemoryStream(_binaryFileData);
BinaryReader binReader = new BinaryReader(memStream);
//binReader.ReadByte(); // file starts with a NULL character for 0-based offset indexing
int nStringOffset = 0;
int nSubsetOffset = 0;
while( (memStream.Position < memStream.Length) && (bRet) )
{
nStringOffset = (int)memStream.Position;
byte [] stringBlock = binReader.ReadBytes(STRING_BLOCK_SIZE);
bRet &= DecodeBlock(stringBlock, ref nStringOffset, ref nSubsetOffset);
}
return bRet;
}
/// <summary>
/// Decodes a string block
/// </summary>
/// <param name="stringBlock">byte array which represents the string block</param>
/// <param name="nStringOffset">current string offset number</param>
/// <param name="nSubsetOffset">reference to a subset variable</param>
/// <returns>true if succeeded</returns>
/// <remarks>If a string crosses the end of a block then it will be cut off
/// without a NT and repeated in full, with a NT, at the start of the next block.
/// For eg "To customize the appearance of a contents file" might become
/// "To customize the (block ending)To customize the appearance of a contents file"
/// when there are 17 bytes left at the end of the block. </remarks>
private bool DecodeBlock( byte[] stringBlock, ref int nStringOffset, ref int nSubsetOffset)
{
bool bRet = true;
MemoryStream memStream = new MemoryStream(stringBlock);
BinaryReader binReader = new BinaryReader(memStream);
while( (memStream.Position < memStream.Length) && (bRet) )
{
bool bFoundTerminator = false;
int nCurOffset = nStringOffset + (int)memStream.Position;
string sTemp = BinaryReaderHelp.ExtractString(ref binReader, ref bFoundTerminator, 0, true, _associatedFile.TextEncoding);
if(nSubsetOffset != 0)
{
_stringDictionary[nSubsetOffset.ToString()] = sTemp.ToString();
}
else
{
_stringDictionary[nCurOffset.ToString()] = sTemp.ToString();
}
if( bFoundTerminator )
{
nSubsetOffset = 0;
}
else
{
nSubsetOffset = nCurOffset;
}
}
return bRet;
}
/// <summary>
/// Indexer which returns the string at a given offset
/// </summary>
public string this[int offset]
{
get
{
if(offset == -1)
return String.Empty;
string sTemp = (string)_stringDictionary[ offset.ToString() ];
if(sTemp == null)
return String.Empty;
return sTemp;
}
}
/// <summary>
/// Indexer which returns the string at a given offset
/// </summary>
public string this[string offset]
{
get
{
if(offset == "-1")
return String.Empty;
string sTemp = (string)_stringDictionary[ offset ];
if(sTemp == null)
return String.Empty;
return sTemp;
}
}
/// <summary>
/// Implement IDisposable.
/// </summary>
public void Dispose()
{
Dispose(true);
// This object will be cleaned up by the Dispose method.
// Therefore, you should call GC.SupressFinalize to
// take this object off the finalization queue
// and prevent finalization code for this object
// from executing a second time.
GC.SuppressFinalize(this);
}
/// <summary>
/// Dispose(bool disposing) executes in two distinct scenarios.
/// If disposing equals true, the method has been called directly
/// or indirectly by a user's code. Managed and unmanaged resources
/// can be disposed.
/// If disposing equals false, the method has been called by the
/// runtime from inside the finalizer and you should not reference
/// other objects. Only unmanaged resources can be disposed.
/// </summary>
/// <param name="disposing">disposing flag</param>
private void Dispose(bool disposing)
{
// Check to see if Dispose has already been called.
if(!this.disposed)
{
// If disposing equals true, dispose all managed
// and unmanaged resources.
if(disposing)
{
// Dispose managed resources.
_binaryFileData = null;
_stringDictionary = null;
}
}
disposed = true;
}
}
}