private IEnumerable<Line> ReadLinesByPosition(ScrollRequest scroll)
{
//TODO: Calculate initial index of first item.
//scroll from specified position
using (var stream = File.Open(Info.FullName, FileMode.Open, FileAccess.Read,FileShare.Delete | FileShare.ReadWrite))
{
int taken = 0;
using (var reader = new StreamReaderExtended(stream, Encoding, false))
{
var startPosition = scroll.Position;
var first = (int)CalculateIndexByPositon(startPosition);
reader.BaseStream.Seek(startPosition, SeekOrigin.Begin);
do
{
var line = reader.ReadLine();
if (line==null) yield break;
var endPosition = reader.AbsolutePosition();
var info = new LineInfo(first + taken + 1, first + taken, startPosition, endPosition);
var ontail = endPosition >= TailInfo.TailStartsAt && DateTime.Now.Subtract(TailInfo.LastTail).TotalSeconds < 1
? DateTime.Now
: (DateTime?)null;
yield return new Line(info, line, ontail);
startPosition = endPosition;
taken++;
} while (taken < scroll.PageSize);
}
}
}
private IEnumerable<Line> ReadLinesByIndex(ScrollRequest scroll)
{
var page = GetPage(scroll);
var relativeIndex = CalculateRelativeIndex(page.Start);
if (relativeIndex == null) yield break;
var offset = relativeIndex.LinesOffset;
using (var stream = File.Open(Info.FullName, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite))
{
using (var reader = new StreamReaderExtended(stream, Encoding, false))
{
//go to starting point
stream.Seek(relativeIndex.Start, SeekOrigin.Begin);
if (offset > 0)
{
//skip number of lines offset
for (int i = 0; i < offset; i++)
reader.ReadLine();
}
//if estimate move to the next start of line
if (relativeIndex.IsEstimate && relativeIndex.Start != 0)
reader.ReadLine();
foreach (var i in Enumerable.Range(page.Start, page.Size))
{
var startPosition = reader.AbsolutePosition();
var line = reader.ReadLine();
var endPosition = reader.AbsolutePosition();
var info = new LineInfo(i + 1, i, startPosition, endPosition);
var ontail = startPosition >= TailInfo.TailStartsAt && DateTime.Now.Subtract(TailInfo.LastTail).TotalSeconds < 1
? DateTime.Now
: (DateTime?)null;
yield return new Line(info, line, ontail);
}
}
}
}
public static IEnumerable<Line> ReadLinesByPosition(this FileInfo source, long[] positions, Func<int, bool> isEndOfTail = null)
{
using (var stream = File.Open(source.FullName, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite))
{
using (var reader = new StreamReaderExtended(stream, Encoding.Default, true))
{
foreach (var position in positions)
{
if (reader.AbsolutePosition() != position)
{
reader.DiscardBufferedData();
stream.Seek(position, SeekOrigin.Begin);
}
var line = reader.ReadLine();
yield return new Line((int)position, line,null);
}
}
}
}