public HelpTopic DeserializeTopic(byte[] input, SerializationOptions options)
{
// Read decompressed length.
if (input.Length < 2)
{
//var e = new InvalidTopicDataEventArgs(topic, input,
// "Not enough bytes for DecodedLength field.");
//this.InvalidTopicData?.Invoke(this, e);
return(null);
}
int outputLength = BitConverter.ToUInt16(input, 0);
byte[] encodedData = new byte[input.Length - 2];
Array.Copy(input, 2, encodedData, 0, encodedData.Length);
// Step 3. Huffman decoding pass.
byte[] compactData;
if (options.HuffmanTree != null)
{
compactData = HuffmanDecode(encodedData, options.HuffmanTree);
}
else
{
compactData = encodedData;
}
// Step 2. Decompression pass.
byte[] binaryData = Decompress(compactData, outputLength, options.Keywords);
// Step 1. Decompile topic.
HelpTopic topic = DecompileTopic(binaryData, options.ControlCharacter);
topic.Source = binaryData;
return(topic);
}
/// <summary>
/// Deserializes the next help database from a binary reader.
/// </summary>
/// <remarks>
/// This method throws an exception if it encounters an irrecoverable
/// error in the input, such as an IO error or malformed input in the
/// meta data. It raises an <c>InvalidTopicData</c> event for each
/// format error it encounters during topic deserialization.
/// </remarks>
public HelpDatabase DeserializeDatabase(
Stream stream, SerializationOptions options)
{
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
if (options == null)
{
options = new SerializationOptions();
}
CheckSignature(stream);
BinaryHelpFileHeader header = ReadFileHeader(stream);
bool isCaseSensitive = (header.Attributes & HelpFileAttributes.CaseSensitive) != 0;
HelpDatabase database = new HelpDatabase(header.DatabaseName, isCaseSensitive);
options.ControlCharacter = Graphic437.GetChars(new byte[] { header.ControlCharacter })[0];
using (Stream streamView = new StreamView(stream, header.DatabaseSize, 0x46))
using (BinaryReader reader = new BinaryReader(streamView))
{
int[] topicOffsets = ReadTopicIndex(reader, header);
// Read Context Strings and Context Map sections.
if (true)
{
string[] contextStrings = ReadContextStrings(reader, header);
UInt16[] contextMap = ReadContextMap(reader, header);
for (int i = 0; i < header.ContextCount; i++)
{
database.AddContext(contextStrings[i], contextMap[i]);
}
}
// Read Keywords section.
if (header.KeywordsOffset > 0)
{
options.Keywords = ReadKeywords(reader, header);
options.Compression |= CompressionFlags.Keyword;
options.Compression |= CompressionFlags.ExtendedKeyword;
}
else
{
options.Keywords = null;
}
// Read Huffman Tree section.
if (header.HuffmanTreeOffset > 0)
{
options.HuffmanTree = ReadHuffmanTree(reader, header);
// file.HuffmanTree.Dump();
options.Compression |= CompressionFlags.Huffman;
}
else
{
options.HuffmanTree = null;
}
// Read topic data.
if (reader.BaseStream.Position != header.TopicTextOffset)
{
throw new InvalidDataException("Incorrect topic position.");
}
for (int i = 0; i < header.TopicCount; i++)
{
if (reader.BaseStream.Position != topicOffsets[i])
{
throw new InvalidDataException("Incorrect topic position.");
}
int inputLength = topicOffsets[i + 1] - topicOffsets[i];
byte[] inputData = reader.ReadBytes(inputLength);
HelpTopic topic = DeserializeTopic(inputData, options);
database.Topics.Add(topic);
}
// TODO: check position
if (reader.BaseStream.Position != topicOffsets[header.TopicCount])
{
throw new InvalidDataException("Incorrect topic end position.");
}
if (reader.BaseStream.Position != header.DatabaseSize)
{
throw new InvalidDataException("Incorrect database size.");
}
#if DEBUG
System.Diagnostics.Debug.WriteLine(string.Format(
"Decoded database {0} of {1} bytes.",
database.Name, header.DatabaseSize));
#endif
}
return(database);
}
