/// <summary>
/// Performs a search for a single word in the index
/// </summary>
/// <param name="word">word to search</param>
/// <param name="MaxHits">maximal hits to return</param>
/// <param name="partialMatches">true if partial word should be matched also
/// ( if this is true a search of 'support' will match 'supports', otherwise not )</param>
/// <param name="titleOnly">true if only search in titles</param>
/// <returns>Returns true if succeeded</returns>
private bool SearchSingleWord(string word, int MaxHits, bool partialMatches, bool titleOnly)
{
string wordLower = word.ToLower();
MemoryStream memStream = new MemoryStream(_binaryFileData);
BinaryReader binReader = new BinaryReader(memStream);
// seek to root node
binReader.BaseStream.Seek(_header.RootOffset, SeekOrigin.Begin);
if (_header.Depth > 2)
{
// unsupported index depth
Debug.WriteLine("FullTextSearcher.SearchSingleWord() - Failed with message: Unsupported index depth !");
Debug.WriteLine("File: " + _associatedFile.ChmFilePath);
Debug.WriteLine(" ");
return(false);
}
if (_header.Depth > 1)
{
// seek to the right leaf node ( if depth == 1, we are at the leaf node)
int freeSpace = binReader.ReadInt16();
for (int i = 0; i < _header.PageCount; ++i)
{
// exstract index entries
int nWLength = (int)binReader.ReadByte();
int nCPosition = (int)binReader.ReadByte();
string sName = BinaryReaderHelp.ExtractString(ref binReader, nWLength - 1, 0, true, _header.TextEncoder);
int nLeafOffset = binReader.ReadInt32();
binReader.ReadInt16(); // unknown
if (sName.CompareTo(wordLower) >= 0)
{
// store current position
long curPos = binReader.BaseStream.Position;
// seek to leaf offset
binReader.BaseStream.Seek(nLeafOffset, SeekOrigin.Begin);
// read leafnode
ReadLeafNode(ref binReader, word, MaxHits, partialMatches, titleOnly);
// return to current position and continue reading index nodes
binReader.BaseStream.Seek(curPos, SeekOrigin.Begin);
}
}
}
return(true);
}
/// <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>
/// Reads a leaf node and extracts documents which holds the searched word
/// </summary>
/// <param name="binReader">reference to the reader</param>
/// <param name="word">word to search</param>
/// <param name="MaxHits">maximal hits to return</param>
/// <param name="partialMatches">true if partial word should be matched also
/// ( if this is true a search of 'support' will match 'supports', otherwise not )</param>
/// <param name="titleOnly">true if only search in titles</param>
private void ReadLeafNode(ref BinaryReader binReader, string word, int MaxHits, bool partialMatches, bool titleOnly)
{
int nNextPageOffset = binReader.ReadInt32();
binReader.ReadInt16(); // unknown
int lfreeSpace = binReader.ReadInt16();
string curFullWord = "";
bool bFound = false;
string wordLower = word.ToLower();
for (;;)
{
if (binReader.BaseStream.Position >= binReader.BaseStream.Length)
{
break;
}
int nWLength = (int)binReader.ReadByte();
if (nWLength == 0)
{
break;
}
int nCPosition = (int)binReader.ReadByte();
string sName = BinaryReaderHelp.ExtractString(ref binReader, nWLength - 1, 0, true, _header.TextEncoder);
int Context = (int)binReader.ReadByte(); // 0...body tag, 1...title tag, others unknown
long nrOfWCL = BinaryReaderHelp.ReadENCINT(ref binReader);
int wclOffset = binReader.ReadInt32();
binReader.ReadInt16(); // unknown
long bytesOfWCL = BinaryReaderHelp.ReadENCINT(ref binReader);
if (nCPosition > 0)
{
curFullWord = CombineStrings(curFullWord, sName, nCPosition);
}
else
{
curFullWord = sName;
}
bFound = false;
if (partialMatches)
{
bFound = (curFullWord.IndexOf(wordLower) >= 0);
}
else
{
bFound = (curFullWord == wordLower);
}
if (bFound)
{
if ((titleOnly && (Context == 1)) || (!titleOnly))
{
// store actual offset
long curPos = binReader.BaseStream.Position;
// found the word, begin with WCL encoding
binReader.BaseStream.Seek(wclOffset, SeekOrigin.Begin);
byte[] wclBytes = binReader.ReadBytes((int)bytesOfWCL);
DecodeWCL(wclBytes, MaxHits, word);
// back and continue reading leafnodes
binReader.BaseStream.Seek(curPos, SeekOrigin.Begin);
}
}
}
}
/// <summary>
/// Decodes a block of url-string data
/// </summary>
/// <param name="dataBlock">block of data</param>
/// <param name="nOffset">current file offset</param>
/// <returns>true if succeeded</returns>
private bool DecodeBlock(byte[] dataBlock, ref int nOffset)
{
bool bRet = true;
int blockOffset = nOffset;
MemoryStream memStream = new MemoryStream(dataBlock);
BinaryReader binReader = new BinaryReader(memStream);
if (nOffset == 0)
{
binReader.ReadByte(); // first block starts with an unknown byte
}
while ((memStream.Position < (memStream.Length - 8)) && (bRet))
{
int entryOffset = blockOffset + (int)memStream.Position;
int urlOffset = binReader.ReadInt32();
int frameOffset = binReader.ReadInt32();
// There is one way to tell where the end of the URL/FrameName
// pairs occurs: Repeat the following: read 2 DWORDs and if both
// are less than the current offset then this is the start of the Local
// strings else skip two NT strings.
// if(( (urlOffset < (entryOffset+8)) && (frameOffset < (entryOffset+8)) ))
// {
// //TODO: add correct string reading if an offset has been found
// /*
// int curOffset = (int)memStream.Position;
//
// memStream.Seek( (long)(blockOffset-urlOffset), SeekOrigin.Begin);
// string sTemp = CHMReader.ExtractString(ref binReader, 0, true);
//
// memStream.Seek( (long)(blockOffset-frameOffset), SeekOrigin.Begin);
// sTemp = CHMReader.ExtractString(ref binReader, 0, true);
//
// memStream.Seek((long)curOffset, SeekOrigin.Begin);
// */
//
//
// int curOffs = (int)memStream.Position;
// BinaryReaderHelp.ExtractString(ref binReader, 0, true, _associatedFile.TextEncoding);
// nOffset += (int)memStream.Position - curOffs;
//
// curOffs = (int)memStream.Position;
// BinaryReaderHelp.ExtractString(ref binReader, 0, true, _associatedFile.TextEncoding);
// nOffset += (int)memStream.Position - curOffs;
// }
// else
{
bool bFoundTerminator = false;
string sTemp = BinaryReaderHelp.ExtractString(ref binReader, ref bFoundTerminator, 0, true, _associatedFile.TextEncoding);
if (sTemp == "")
{
//nOffset = nOffset + 1 + (int)memStream.Length - (int)memStream.Position;
memStream.Seek(memStream.Length - 1, SeekOrigin.Begin);
}
else
{
_urlDictionary[entryOffset.ToString()] = sTemp.ToString();
_framenameDictionary[entryOffset.ToString()] = sTemp.ToString();
}
}
}
return(bRet);
}
/// <summary>
/// Decodes an #system file entry
/// </summary>
/// <param name="binReader">binary reader reference</param>
/// <returns>true if succeeded</returns>
private bool DecodeEntry(ref BinaryReader binReader)
{
bool bRet = true;
int code = (int)binReader.ReadInt16(); // entry code, WORD
int length = (int)binReader.ReadInt16(); // length of entry
switch (code)
{
case 0:
{
_contentsFile = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 1:
{
_indexFile = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 2:
{
_defaultTopic = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 3:
{
_title = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 4:
{
int nTemp = 0;
nTemp = binReader.ReadInt32(); // read DWORD LCID
_culture = new CultureInfo(nTemp);
if (_culture != null)
{
_associatedFile.TextEncoding = Encoding.GetEncoding(_culture.TextInfo.ANSICodePage);
}
nTemp = binReader.ReadInt32(); // read DWORD DBCS
_dbcs = (nTemp == 1);
nTemp = binReader.ReadInt32(); // read DWORD Fulltext search
_fullTextSearch = (nTemp == 1);
nTemp = binReader.ReadInt32(); // read DWORD has klinks
_hasKLinks = (nTemp != 0);
nTemp = binReader.ReadInt32(); // read DWORD has alinks
_hasALinks = (nTemp != 0);
// read the rest of code 4 (not important for us)
byte[] temp = new byte[length - (5 * 4)];
temp = binReader.ReadBytes(length - (5 * 4));
}; break;
case 5:
{
_defaultWindow = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 6:
{
_compileFile = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 7:
{
if (_fileVersion > 2)
{
_binaryIndexURLTableID = (uint)binReader.ReadInt32();
}
else
{
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}
}; break;
case 8:
{
// abbreviation (not interresting for us)
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}; break;
case 9:
{
_compilerVersion = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
case 10:
{
// timestamp of the file (not interresting for us)
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}; break;
case 11:
{
if (_fileVersion > 2)
{
_binaryTOCURLTableID = (uint)binReader.ReadInt32();
}
else
{
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}
}; break;
case 12:
{
// number of information bytes
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}; break;
case 13:
{
// copy of file #idxhdr
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}; break;
case 14:
{
// custom tabs for HH viewer
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}; break;
case 15:
{
// a checksum
byte[] read = binReader.ReadBytes(length);
int i = read.Length;
}; break;
case 16:
{
// Default Font=string,number,number
// The string is the name of the font, the first number is the
// point size & the last number is the character set used by the font.
// For acceptable values see *_CHARSET defines in wingdi.h from the
// Windows SDK or the same file in MinGW or Wine.
// Most of the time you will only want to use 0, which is the value for ANSI,
// which is the subset of ASCII used by Windows.
_defaultFont = BinaryReaderHelp.ExtractString(ref binReader, length, 0, true, _associatedFile.TextEncoding);
}; break;
default:
{
byte[] temp = new byte[length];
temp = binReader.ReadBytes(length);
//bRet = false;
int i = temp.Length;
}; break;
}
return(bRet);
}