encoding.cs

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				// Build a web encoding class name.
				String encName = "System.Text.ENC" +
								 name.ToLower(CultureInfo.InvariantCulture)
								 	.Replace('-', '_');

				// Look for a code page converter in this assembly.
				Assembly assembly = Assembly.GetExecutingAssembly();
				Type type = assembly.GetType(encName);
				if(type != null)
				{
					return (Encoding)(Activator.CreateInstance(type));
				}

				// Look in any assembly, in case the application
				// has provided its own code page handler.
				type = Type.GetType(encName);
				if(type != null)
				{
					return (Encoding)(Activator.CreateInstance(type));
				}
#endif

				// We have no idea how to handle this encoding name.
				throw new NotSupportedException
					(String.Format(_("NotSupp_EncodingName"), name));
			}

#endif // !ECMA_COMPAT

	// Get a hash code for this instance.
	public override int GetHashCode()
			{
				return codePage;
			}

	// Get the maximum number of bytes needed to encode a
	// specified number of characters.
	public abstract int GetMaxByteCount(int charCount);

	// Get the maximum number of characters needed to decode a
	// specified number of bytes.
	public abstract int GetMaxCharCount(int byteCount);

	// Get the identifying preamble for this encoding.
	public virtual byte[] GetPreamble()
			{
				return new byte [0];
			}

	// Decode a buffer of bytes into a string.
	public virtual String GetString(byte[] bytes, int index, int count)
			{
				return new String(GetChars(bytes, index, count));
			}
	public virtual String GetString(byte[] bytes)
			{
				return new String(GetChars(bytes));
			}

#if !ECMA_COMPAT

	// Get the mail body name for this encoding.
	public virtual String BodyName
			{
				get
				{
					return InternalBodyName;
				}
			}

	// Get the code page represented by this object.
	public virtual int CodePage
			{
				get
				{
					return InternalCodePage;
				}
			}

	// Get the human-readable name for this encoding.
	public virtual String EncodingName
			{
				get
				{
					return InternalEncodingName;
				}
			}

	// Get the mail agent header name for this encoding.
	public virtual String HeaderName
			{
				get
				{
					return InternalHeaderName;
				}
			}

	// Determine if this encoding can be displayed in a Web browser.
	public virtual bool IsBrowserDisplay
			{
				get
				{
					return InternalIsBrowserDisplay;
				}
			}

	// Determine if this encoding can be saved from a Web browser.
	public virtual bool IsBrowserSave
			{
				get
				{
					return InternalIsBrowserSave;
				}
			}

	// Determine if this encoding can be displayed in a mail/news agent.
	public virtual bool IsMailNewsDisplay
			{
				get
				{
					return InternalIsMailNewsDisplay;
				}
			}

	// Determine if this encoding can be saved from a mail/news agent.
	public virtual bool IsMailNewsSave
			{
				get
				{
					return InternalIsMailNewsSave;
				}
			}

	// Get the IANA-preferred Web name for this encoding.
	public virtual String WebName
			{
				get
				{
					return InternalWebName;
				}
			}

	// Get the Windows code page represented by this object.
	public virtual int WindowsCodePage
			{
				get
				{
					return InternalWindowsCodePage;
				}
			}

	// Get the mail body name for this encoding.
	internal virtual String InternalBodyName
			{
				get
				{
					return null;
				}
			}

	// Get the code page represented by this object.
	internal virtual int InternalCodePage
			{
				get
				{
					return codePage;
				}
			}

	// Get the human-readable name for this encoding.
	internal virtual String InternalEncodingName
			{
				get
				{
					return null;
				}
			}

	// Get the mail agent header name for this encoding.
	internal virtual String InternalHeaderName
			{
				get
				{
					return null;
				}
			}

	// Determine if this encoding can be displayed in a Web browser.
	internal virtual bool InternalIsBrowserDisplay
			{
				get
				{
					return false;
				}
			}

	// Determine if this encoding can be saved from a Web browser.
	internal virtual bool InternalIsBrowserSave
			{
				get
				{
					return false;
				}
			}

	// Determine if this encoding can be displayed in a mail/news agent.
	internal virtual bool InternalIsMailNewsDisplay
			{
				get
				{
					return false;
				}
			}

	// Determine if this encoding can be saved from a mail/news agent.
	internal virtual bool InternalIsMailNewsSave
			{
				get
				{
					return false;
				}
			}

	// Get the IANA-preferred Web name for this encoding.
	internal virtual String InternalWebName
			{
				get
				{
					return null;
				}
			}

	// Get the Windows code page represented by this object.
	internal virtual int InternalWindowsCodePage
			{
				get
				{
					// We make no distinction between normal and
					// Windows code pages in this implementation.
					return codePage;
				}
			}

#endif // !ECMA_COMPAT

	// Storage for standard encoding objects.
	private static Encoding asciiEncoding = null;
	private static Encoding bigEndianEncoding = null;
	private static Encoding defaultEncoding = null;
	private static Encoding utf7Encoding = null;
	private static Encoding utf8Encoding = null;
	private static Encoding unicodeEncoding = null;
	private static Encoding isoLatin1Encoding = null;
	private static Encoding utf32Encoding = null;
	private static Encoding bigEndianUtf32Encoding = null;

	// Get the standard ASCII encoding object.
	public static Encoding ASCII
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(asciiEncoding == null)
						{
							asciiEncoding = new ASCIIEncoding();
						}
						return asciiEncoding;
					}
				}
			}

	// Get the standard big-endian Unicode encoding object.
	public static Encoding BigEndianUnicode
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(bigEndianEncoding == null)
						{
							bigEndianEncoding = new UnicodeEncoding(true, true);
						}
						return bigEndianEncoding;
					}
				}
			}

	// Get the default encoding object.
	public static Encoding Default
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(defaultEncoding == null)
						{
							// See if the underlying system knows what
							// code page handler we should be using.
							int codePage = DefaultEncoding.InternalCodePage();
							if(codePage != 0)
							{
								try
								{
									defaultEncoding = GetEncoding(codePage);
								}
								catch(NotSupportedException)
								{
									defaultEncoding = new DefaultEncoding();
								}
							}
							else
							{
								defaultEncoding = new DefaultEncoding();
							}
						}
						return defaultEncoding;
					}
				}
			}

	// Get the ISO Latin1 encoding object.
	private static Encoding ISOLatin1
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(isoLatin1Encoding == null)
						{
							isoLatin1Encoding = new Latin1Encoding();
						}
						return isoLatin1Encoding;
					}
				}
			}

	// Get the standard UTF-7 encoding object.
#if ECMA_COMPAT
	private
#else
	public
#endif
	static Encoding UTF7
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(utf7Encoding == null)
						{
							utf7Encoding = new UTF7Encoding();
						}
						return utf7Encoding;
					}
				}
			}

	// Get the standard UTF-8 encoding object.
	public static Encoding UTF8
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(utf8Encoding == null)
						{
							utf8Encoding = new UTF8Encoding(true);
						}
						return utf8Encoding;
					}
				}
			}

	// Get the standard little-endian Unicode encoding object.
	public static Encoding Unicode
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(unicodeEncoding == null)
						{
							unicodeEncoding = new UnicodeEncoding();
						}
						return unicodeEncoding;
					}
				}
			}

	// Get the standard UTF-32 encoding object.
#if !ECMA_COMPAT && CONFIG_FRAMEWORK_1_2
	public
#else
	internal
#endif
	static Encoding UTF32
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(utf32Encoding == null)
						{
							utf32Encoding = new UTF32Encoding();
						}
						return utf32Encoding;
					}
				}
			}

	// Get the big-endian UTF-32 encoding object.
	private static Encoding BigEndianUTF32
			{
				get
				{
					lock(typeof(Encoding))
					{
						if(bigEndianUtf32Encoding == null)
						{
							bigEndianUtf32Encoding = new UTF32Encoding
								(true, true);
						}
						return bigEndianUtf32Encoding;
					}
				}
			}

	// Forwarding decoder implementation.
	private sealed class ForwardingDecoder : Decoder
	{
		private Encoding encoding;

		// Constructor.
		public ForwardingDecoder(Encoding enc)
				{
					encoding = enc;
				}

		// Override inherited methods.
		public override int GetCharCount(byte[] bytes, int index, int count)
				{
					return encoding.GetCharCount(bytes, index, count);
				}
		public override int GetChars(byte[] bytes, int byteIndex,
									 int byteCount, char[] chars,
									 int charIndex)
				{
					return encoding.GetChars(bytes, byteIndex, byteCount,
											 chars, charIndex);
				}

	} // class ForwardingDecoder

	// Forwarding encoder implementation.
	private sealed class ForwardingEncoder : Encoder
	{
		private Encoding encoding;

		// Constructor.
		public ForwardingEncoder(Encoding enc)
				{
					encoding = enc;
				}

		// Override inherited methods.
		public override int GetByteCount(char[] chars, int index,
										 int count, bool flush)
				{
					return encoding.GetByteCount(chars, index, count);
				}
		public override int GetBytes(char[] chars, int charIndex,
									 int charCount, byte[] bytes,
									 int byteCount, bool flush)
				{
					return encoding.GetBytes(chars, charIndex, charCount,
											 bytes, byteCount);
				}

	} // class ForwardingEncoder

}; // class Encoding

}; // namespace System.Text