private void FindLogicalBounds(bool incrementalMode)
{
TextStreamPosition defaultBegin = new TextStreamPosition(0, TextStreamPosition.AlignMode.BeginningOfContainingBlock, textStreamPositioningParams);
TextStreamPosition defaultEnd = DetectEndPositionFromMediaSize();
TextStreamPosition newBegin = incrementalMode ? beginPosition : defaultBegin;
TextStreamPosition newEnd = defaultEnd;
beginPosition = defaultBegin;
endPosition = defaultEnd;
try
{
if (!incrementalMode && beginFinder != null)
{
newBegin = FindBound(beginFinder, VolatileStream, StreamEncoding, "beginning", textStreamPositioningParams);
}
if (endFinder != null)
{
newEnd = FindBound(endFinder, VolatileStream, StreamEncoding, "end", textStreamPositioningParams);
}
}
finally
{
beginPosition = newBegin;
endPosition = newEnd;
}
}
static bool HeuristicallyDetectWhetherMultithreadingMakesSense(CreateParserParams parserParams,
TextStreamPositioningParams textStreamPositioningParams)
{
#if SILVERLIGHT
return(false);
#else
if (System.Environment.ProcessorCount == 1)
{
return(false);
}
long approxBytesToRead;
if (parserParams.Direction == MessagesParserDirection.Forward)
{
approxBytesToRead = new TextStreamPosition(parserParams.Range.Value.End, textStreamPositioningParams).StreamPositionAlignedToBlockSize
- new TextStreamPosition(parserParams.StartPosition, textStreamPositioningParams).StreamPositionAlignedToBlockSize;
}
else
{
approxBytesToRead = new TextStreamPosition(parserParams.StartPosition, textStreamPositioningParams).StreamPositionAlignedToBlockSize
- new TextStreamPosition(parserParams.Range.Value.Begin, textStreamPositioningParams).StreamPositionAlignedToBlockSize;
}
if (approxBytesToRead < MultiThreadedStrategy <int> .GetBytesToParsePerThread(textStreamPositioningParams) * 2)
{
return(false);
}
return(true);
#endif
}
/// <summary>
/// Prepares object for sequential reading from the stream.
/// The object is loaded with peice of text that contains the character pointer by <paramref name="initialPosition"/>.
/// Data is loaded from the underlying stream.
/// </summary>
public void BeginReading(long initialPosition, TextAccessDirection direction)
{
if (readingStarted)
{
throw new InvalidOperationException("Cannot start reading session. Another reading session has already been started");
}
if (initialPosition < 0)
{
throw new ArgumentException("Negative positions are not allowed", "initialPosition");
}
readingStarted = true;
this.direction = direction;
this.startPosition = new TextStreamPosition(initialPosition, textStreamPositioningParams);
streamPositionToReadFromNextTime = new TextStreamPosition(initialPosition, textStreamPositioningParams).StreamPositionAlignedToBlockSize;
streamPositionAlignedToBufferSize = streamPositionToReadFromNextTime;
decoderNeedsReloading = EncodingNeedsReloading();
textBufferLength = 0;
textBufferAsString = "";
charsCutFromBeginningOfTextBuffer = 0;
charsCutFromEndOfTextBuffer = 0;
AdvanceBufferInternal(0);
}
private static long TextStreamPositionToStreamPosition_Approx(long pos, Encoding encoding, TextStreamPositioningParams positioningParams)
{
TextStreamPosition txtPos = new TextStreamPosition(pos, positioningParams);
int byteCount;
if (encoding == Encoding.UTF8)
{
byteCount = txtPos.CharPositionInsideBuffer; // usually utf8 use latin chars. 1 char -> 1 byte.
}
else if (encoding == Encoding.Unicode || encoding == Encoding.BigEndianUnicode)
{
byteCount = txtPos.CharPositionInsideBuffer * 2; // usually UTF16 does not user surrogates. 1 char -> 2 bytes.
}
else
{
byteCount = encoding.GetMaxByteCount(txtPos.CharPositionInsideBuffer); // default formula
}
return(txtPos.StreamPositionAlignedToBlockSize + byteCount);
}
/// <summary>
/// Creates valid TextStreamPosition object that points to the charachter that starts at or contains
/// the byte defined by <paramref name="streamPosition"/>
/// </summary>
/// <param name="streamPosition">Stream position. In other words 0-based byte index in stream's data.</param>
/// <param name="streamEncoding">Manadatory encoding information of the stream</param>
/// <param name="stream"></param>
/// <returns>Valid TextStreamPosition object</returns>
public static async Task <TextStreamPosition> StreamPositionToTextStreamPosition(long streamPosition, Encoding streamEncoding, Stream stream, TextStreamPositioningParams textStreamPositioningParams)
{
if (streamEncoding == null)
{
throw new ArgumentNullException("streamEncoding");
}
TextStreamPosition tmp = new TextStreamPosition(streamPosition, textStreamPositioningParams);
#if !SILVERLIGHT
if (streamEncoding.IsSingleByte)
{
return(tmp);
}
#endif
if (streamEncoding == Encoding.Unicode || streamEncoding == Encoding.BigEndianUnicode)
{
return(new TextStreamPosition(tmp.StreamPositionAlignedToBlockSize, tmp.CharPositionInsideBuffer / 2, textStreamPositioningParams));
}
#if !SILVERLIGHT
if (streamEncoding == Encoding.UTF32)
{
return(new TextStreamPosition(tmp.StreamPositionAlignedToBlockSize, tmp.CharPositionInsideBuffer / 4, textStreamPositioningParams));
}
#endif
if (stream == null)
{
throw new ArgumentNullException("stream object is required to determine text stream position with given encoding", "stream");
}
var boundedStream = new BoundedStream();
boundedStream.SetStream(stream, false);
boundedStream.SetBounds(null, streamPosition);
StreamTextAccess tmpTextAccess = new StreamTextAccess(boundedStream, streamEncoding, textStreamPositioningParams);
await tmpTextAccess.BeginReading(tmp.StreamPositionAlignedToBlockSize, TextAccessDirection.Forward);
tmp = tmpTextAccess.CharIndexToPosition(tmpTextAccess.BufferString.Length);
tmpTextAccess.EndReading();
return(tmp);
}
/// <summary>
/// Returns char index in BufferString string that has absolute position <paramref name="pos"/>
/// </summary>
public int PositionToCharIndex(TextStreamPosition pos)
{
int?tmp = null;
if (direction == TextAccessDirection.Backward)
{
if (pos.StreamPositionAlignedToBlockSize == streamPositionAlignedToBufferSize)
{
tmp = pos.CharPositionInsideBuffer;
}
else if (pos.StreamPositionAlignedToBlockSize == streamPositionAlignedToBufferSize + textStreamPositioningParams.AlignmentBlockSize)
{
tmp = pos.CharPositionInsideBuffer + textBufferLength - charactersLeftFromPrevBlock;
}
}
else
{
if (pos.StreamPositionAlignedToBlockSize == streamPositionAlignedToBufferSize)
{
tmp = pos.CharPositionInsideBuffer + charactersLeftFromPrevBlock;
}
else if (pos.StreamPositionAlignedToBlockSize == streamPositionAlignedToBufferSize - textStreamPositioningParams.AlignmentBlockSize)
{
tmp = pos.CharPositionInsideBuffer - totalCharactersInPrevBlock + charactersLeftFromPrevBlock;
}
}
if (tmp != null)
{
int ret = tmp.Value - charsCutFromBeginningOfTextBuffer;
if (ret > textBufferAsString.Length)
{
return(textBufferAsString.Length);
}
if (ret >= 0)
{
return(ret);
}
}
throw new ArgumentOutOfRangeException("position maps to the character that doesn't belong to current buffer");
}
