private void FlushLogicalLine(LogicalLinesHistoryQueue logicalLinesHistoryQueue = null)
{
if (_logicalLine.IsEmpty)
{
return;
}
_logicalLine.IsVisible = !ShouldBeHided() && ShouldBeShown();
if (
(_logicalLine.IsVisible || _afterCounter > 0) &&
!SkipFromNumLines())
{
var forPrinting = new LogicalLinesHistoryQueue();
PrepareLogicalLineForPrinting(_logicalLine, forPrinting);
if (logicalLinesHistoryQueue == null)
{
PrintLogicalLines(forPrinting);
}
else
{
logicalLinesHistoryQueue.Enqueue(forPrinting);
}
if (_logicalLine.IsVisible)
{
_afterCounter = Configs.ContextAfter;
}
}
_logicalLinesHistoryQueue.Enqueue(_logicalLine);
_logicalLine = new LogicalLine();
}
private void PrepareLogicalLineForPrinting(LogicalLine logicalLine, LogicalLinesHistoryQueue prepared)
{
if (Configs.IsContextBeforeUsed &&
_logicalLinesHistoryQueue.Any() &&
_logicalLine.IsVisible)
{
prepared.Enqueue(_logicalLinesHistoryQueue);
_logicalLinesHistoryQueue.Clear();
}
prepared.Enqueue(logicalLine);
if (_afterCounter > 0)
{
--_afterCounter;
}
}
// Optimization used:
// read from end in pages by XXX bytes to a memory stream
// and stops to read if _startFromNum lines found
//
// Will not works, if line length is greater than PAGE_SIZE
private bool ProcessStreamInPages(Stream stream, LogicalLinesHistoryQueue logicalLines)
{
if (!CanProcessInPages())
{
return(false);
}
var encoding = DetectEncoding(stream);
var historyDeep = _startFromNum * (Configs.ContextLines + 1);
var foundLines = new LogicalLinesHistoryQueue(historyDeep);
var from = FileSize;
while (from != 0 && foundLines.Count != historyDeep)
{
var buf = new byte[Constants.REVERS_SEARCH_PAGE_SIZE];
var pageLines = new LogicalLinesHistoryQueue(historyDeep);
from = Math.Max(0, from - Constants.REVERS_SEARCH_PAGE_SIZE);
stream.Seek(from, SeekOrigin.Begin);
var sz = stream.Read(buf, 0, Constants.REVERS_SEARCH_PAGE_SIZE);
Stream ms = null;
try
{
ms = new MemoryStream(buf, 0, sz);
using var sr = new StreamReader(ms, encoding,
from == 0 // ignore BOM only at file beginning
);
ms = null; // prevent disposing several times
if (from != 0)
{
var nul = sr.ReadLine(); // ignore first line, may be incomplete
var szBytes = encoding.GetByteCount(nul ?? string.Empty);
if (szBytes >= Constants.REVERS_SEARCH_PAGE_SIZE) // extra long line
{
return(false);
}
from += szBytes;
}
var s = sr.ReadLine();
while (s != null)
{
if (encoding.GetByteCount(s) >= Constants.REVERS_SEARCH_PAGE_SIZE)
{
return(false);
}
ProcessReadLine(s, pageLines);
s = sr.ReadLine();
}
}
finally
{
#pragma warning disable CA1508 // Avoid dead conditional code
ms?.Dispose();
#pragma warning restore CA1508 // Avoid dead conditional code
}
FlushLogicalLine(pageLines);
pageLines.Enqueue(foundLines);
foundLines.ReplaceBy(pageLines);
LastPos = FileSize - from;
}
logicalLines.ReplaceBy(foundLines);
// because lines was searched in pages, line numbers are irrelevant
logicalLines.SetLinesNumberToUnknown();
LastPos = FileSize;
return(true);
}
