public HuffmanTable this[char from]
{
get
{
// Validate
if ((from < '\x0001') || (from > '\x007f'))
{
if (from != HuffmanItem.StartOrEnd)
{
throw new ArgumentException(from.ToString(), "from");
}
}
// Attach to the table
HuffmanTable table = Tables.Find(t => t.Source[0] == from);
// Found it
if (null != table)
{
return(table);
}
// Create a new table
table = new HuffmanTable {
Source = new string( new char[] { from } )
};
// Remember it
Tables.Add(table);
// Report
return(table);
}
}
public HuffmanTable this[char from]
{
get
{
// Validate
if ((from < '\x0001') || (from > '\x007f'))
if (from != HuffmanItem.StartOrEnd)
throw new ArgumentException( from.ToString(), "from" );
// Attach to the table
HuffmanTable table = Tables.Find( t => t.Source[0] == from );
// Found it
if (null != table)
return table;
// Create a new table
table = new HuffmanTable { Source = new string( new char[] { from } ) };
// Remember it
Tables.Add( table );
// Report
return table;
}
}
/// <summary>
/// Ergänzt eine alternative Auflösungssequenz.
/// </summary>
/// <param name="sequence">Die neue Sequenz.</param>
public void AddAlternateSequence(string sequence)
{
// Validate
HuffmanTable.ValidateSequence(sequence);
// All of it
Dictionary <string, string> sequences = new Dictionary <string, string>();
// Load
if (!string.IsNullOrEmpty(AlternateSequences))
{
sequences = AlternateSequences.Split(';').ToDictionary(s => s);
}
// Add the new one
sequences[sequence] = sequence;
// Push back
AlternateSequences = string.Join(";", sequences.Keys.ToArray());
}
/// <summary>
/// Ermittelt zu einer Sequence von UTF-8 codierten Zeichen die zugehörige Übergangssequenz.
/// </summary>
/// <param name="text">Die Zeichensequenz.</param>
/// <param name="offset">Das erste auszuwertende Zeichen.</param>
/// <param name="length">Die Anzahl der auszuwertenden Zeichen.</param>
/// <param name="good">Meldet die Anzahl der bearbeiteten Zeichen.</param>
/// <param name="blindEscape">Gesetzt um eine vorhandene Ausnahmesequenz so oft wie möglich zu verwenden.</param>
/// <returns>Die ermittelte Übergangssequenz.</returns>
public string GetSequence(byte[] text, int offset, int length, bool blindEscape, out int good)
{
// Result
StringBuilder result = new StringBuilder();
// Previous item
char?prev = null;
// Count processed items
good = -1;
// Process all
while (length-- > 0)
{
// Load
byte next = text[offset++];
char item = (char)next;
// Not allowed
if (next < 1)
{
break;
}
// Check for escape mode
if ((next > 127) && (HuffmanItem.StartOrEnd != item))
{
// Not allowed at the very beginning
if (!prev.HasValue)
{
break;
}
// Check out the escape sequence
string escape = this[prev.Value, HuffmanItem.PassThrough];
if (string.IsNullOrEmpty(escape))
{
break;
}
// Enter the escape sequence and the current character
result.Append(escape);
AppendHex(result, next);
// Count it
++good;
// Repeat
while (length-- > 0)
{
// Load
next = text[offset++];
item = (char)next;
// Forbidden
if (next < 1)
{
break;
}
// Always add
AppendHex(result, next);
// Count it
++good;
// Done
if (next <= 127)
{
break;
}
}
// Forbidden
if (next < 1)
{
break;
}
}
else
{
// Not for the first byte
if (prev.HasValue)
{
// Get the sequence
string sequence = this[prev.Value, item];
// Done
if (string.IsNullOrEmpty(sequence))
{
// See if the current target is a confirmed escape character
HuffmanTable table = this[prev.Value];
// Respect client settings
if (!blindEscape)
{
// No confirmed escapes at all
if (null == table.ConfirmedEscapes)
{
break;
}
// Not an confirmed escape
if (!table.ConfirmedEscapes.Contains(item))
{
break;
}
}
// Read the escape sequence
sequence = table[HuffmanItem.PassThrough];
if (string.IsNullOrEmpty(sequence))
{
break;
}
// Did it all
if (item == HuffmanItem.StartOrEnd)
{
// Append escape
result.Append(sequence);
// Append terminator
result.Append("00000000");
// Count it
++good;
// Done
break;
}
// Create new sequence
StringBuilder escape = new StringBuilder(sequence);
// Append the item
AppendHex(escape, (byte)item);
// Use it
sequence = escape.ToString();
}
// Append
result.Append(sequence);
}
// Count it
++good;
}
// Just remember for next step
prev = item;
}
// Report
return(result.ToString());
}
