private RelativeIndex CalculateRelativeIndex(int index, ref IndexCollection indexCollection,
LastValueWrapper lastValueWrapper)
{
var firstLineInContainer = 0;
var lastLineInContainer = 0;
while (indexCollection != null)
{
foreach (var sparseIndex in indexCollection.Indicies)
{
lastLineInContainer += sparseIndex.LineCount;
if (index < lastLineInContainer)
{
//It could be that the user is scrolling into a part of the file
//which is still being indexed [or will never be indexed].
//In this case we need to estimate where to scroll to
if (sparseIndex.LineCount != 0 && sparseIndex.Indicies.Count == 0)
{
//return estimate here!
var lines = sparseIndex.LineCount;
var bytes = sparseIndex.End - sparseIndex.Start;
var bytesPerLine = bytes / lines;
var estimate = index * bytesPerLine;
return(new RelativeIndex(index, estimate, 0, true));
}
var relativePosition = (index - firstLineInContainer);
var relativeIndex = relativePosition / sparseIndex.Compression;
var offset = relativePosition % sparseIndex.Compression;
if (relativeIndex >= sparseIndex.IndexCount)
{
relativeIndex = sparseIndex.IndexCount - 1;
}
var start = relativeIndex == 0 ? 0 : sparseIndex.Indicies[relativeIndex - 1];
return(new RelativeIndex(index, start, offset, false));
}
firstLineInContainer = firstLineInContainer + sparseIndex.LineCount;
}
lastValueWrapper.LastEndPosition += indexCollection.Indicies
.Where(localIndex => localIndex.IndexCount > 0)
.Sum(localIndex => localIndex.Indicies[localIndex.IndexCount - 1]);
indexCollection = indexCollection.Previous as IndexCollection;
}
return(null);
}
public IEnumerable <Line> ReadLines(ScrollRequest scroll)
{
var current = ReverseLinking(this);
var page = GetPage(scroll, this);
var lastValueWrapper = new LastValueWrapper();
if (page.Size == 0)
{
yield break;
}
while (current != null)
{
using (
var stream = File.Open(current.Info.FullName, FileMode.Open, FileAccess.Read,
FileShare.Delete | FileShare.ReadWrite))
{
using (var reader = new StreamReaderExtended(stream, current.Encoding, false))
{
if (page.Size == 0)
{
yield break;
}
if (lastValueWrapper.LastPageIndex == page.Start + page.Size)
{
yield break;
}
var counter = 0;
long lastEndPos = 0;
foreach (
var i in
Enumerable.Range(
lastValueWrapper.LastPageIndex > 0 ? lastValueWrapper.LastPageIndex : page.Start,
page.Size - counter))
{
if (i == page.Start + page.Size)
{
yield break;
}
if (i - lastValueWrapper.LastMatchesSize > current.Count - 1)
{
lastValueWrapper.LastEndPosition += lastEndPos + 1;
lastValueWrapper.LastMatchesSize += current.Count;
break;
}
var start = current.Matches[i - lastValueWrapper.LastMatchesSize];
var startPosition = reader.AbsolutePosition();
if (startPosition != start)
{
reader.DiscardBufferedData();
reader.BaseStream.Seek(start, SeekOrigin.Begin);
}
startPosition = reader.AbsolutePosition();
var line = reader.ReadLine();
var endPosition = reader.AbsolutePosition();
var info = new LineInfo(i + 1, i, startPosition + lastValueWrapper.LastEndPosition,
endPosition + lastValueWrapper.LastEndPosition);
var ontail = endPosition >= TailInfo.TailStartsAt &&
DateTime.Now.Subtract(TailInfo.LastTail).TotalSeconds < 1
? DateTime.Now
: (DateTime?)null;
yield return(new Line(info, line, ontail));
lastValueWrapper.LastPageIndex = i + 1;
counter++;
lastEndPos = endPosition;
if (reader.EndOfStream)
{
lastValueWrapper.LastEndPosition += endPosition + 1;
lastValueWrapper.LastMatchesSize += current.Count;
break;
}
}
}
}
current = current.Next as FileSearchResult;
}
}
private IEnumerable <Line> ReadLinesByIndex(ScrollRequest scroll)
{
var current = this;
var lastValueWrapper = new LastValueWrapper();
var iterationCounter = 0;
var page = GetPage(scroll, current);
var relativeIndex = CalculateRelativeIndex(page.Start, ref current, lastValueWrapper);
while (relativeIndex != null && current != null)
{
if (current.Indicies.Length > 0 && current.Indicies.Any(t => t.Indicies.Count == 0))
{
iterationCounter++;
current = current.Previous as IndexCollection;
continue;
}
if (lastValueWrapper.LastPageIndex == page.Start + page.Size)
{
yield break;
}
var offset = relativeIndex.LinesOffset;
using (
var stream = File.Open(current.Info.FullName, FileMode.Open, FileAccess.Read,
FileShare.Delete | FileShare.ReadWrite))
{
using (var reader = new StreamReaderExtended(stream, current.Encoding, false))
{
//go to starting point
stream.Seek((iterationCounter > 0) ? 0 : relativeIndex.Start, SeekOrigin.Begin);
if (iterationCounter == 0 && offset > 0)
{
//skip number of lines offset
for (var i = 0; i < offset; i++)
{
reader.ReadLine();
}
}
//if estimate move to the next start of line
if (iterationCounter == 0 && relativeIndex.IsEstimate && relativeIndex.Start != 0)
{
reader.ReadLine();
}
foreach (
var i in
Enumerable.Range((iterationCounter > 0) ? lastValueWrapper.LastPageIndex : page.Start,
page.Size))
{
if (i == page.Start + page.Size)
{
yield break;
}
var startPosition = reader.AbsolutePosition() + lastValueWrapper.LastEndPosition;
var line = reader.ReadLine();
var endPosition = reader.AbsolutePosition() + lastValueWrapper.LastEndPosition;
var info = new LineInfo(i + 1, i, startPosition, endPosition);
var ontail = startPosition >= current.TailInfo.TailStartsAt &&
DateTime.Now.Subtract(current.TailInfo.LastTail).TotalSeconds < 1
? DateTime.Now
: (DateTime?)null;
yield return(new Line(info, line, ontail));
lastValueWrapper.LastPageIndex = i + 1;
if (reader.EndOfStream)
{
lastValueWrapper.LastEndPosition += endPosition + 1;
break;
}
}
}
}
iterationCounter++;
current = current.Previous as IndexCollection;
}
}
