Import TechBot

svn path=/trunk/; revision=13064

irc/TechBot/CHMLibrary/CHMDecoding/CHMStrings.cs

@@ -0,0 +1,256 @@
+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;         
+		}
+	}
+}