/// <summary>
/// Determines the encoding of a file
/// </summary>
/// <returns></returns>
public static Encoding GetEncoding(this FileInfo source)
{
using (var stream = File.Open(source.FullName, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite))
{
using (var reader = new StreamReaderExtended(stream, true))
{
var something = reader.Peek();
return reader.CurrentEncoding;
}
}
}
public IEnumerable<FileSegment> LoadSegments()
{
using (var stream = File.Open(_info.FullName, FileMode.Open, FileAccess.Read,FileShare.Delete | FileShare.ReadWrite))
{
var fileLength = stream.Length;
stream.Seek(0, SeekOrigin.Begin);
using (var reader = new StreamReaderExtended(stream, true))
{
if (reader.EndOfStream || fileLength == 0)
{
yield return new FileSegment(0, 0, 0, FileSegmentType.Tail);
yield break;
}
if (fileLength < _initialTail)
{
yield return new FileSegment(0, 0, fileLength, FileSegmentType.Tail);
yield break;
}
var headStartsAt = reader.FindNextEndOfLinePosition(fileLength - _initialTail);
long currentEnfOfPage = 0;
long previousEndOfPage = 0;
int index = 0;
do
{
var approximateEndOfPage = currentEnfOfPage + _segmentSize;
if (approximateEndOfPage >= headStartsAt)
{
yield return new FileSegment(index, previousEndOfPage, headStartsAt, FileSegmentType.Head);
break;
}
currentEnfOfPage = reader.FindNextEndOfLinePosition(approximateEndOfPage);
yield return new FileSegment(index, previousEndOfPage, currentEnfOfPage, FileSegmentType.Head);
index++;
previousEndOfPage = currentEnfOfPage;
} while (true);
index ++;
yield return new FileSegment(index, headStartsAt, fileLength, FileSegmentType.Tail);
}
}
}
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);
}
}
}
}
private FileSegmentSearchResult Search(long start, long end)
{
long lastPosition = 0;
using (var stream = File.Open(Info.FullName, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite))
{
if (stream.Length < start)
{
start = 0;
end = stream.Length;
}
long[] lines;
using (var reader = new StreamReaderExtended(stream, true))
{
stream.Seek(start, SeekOrigin.Begin);
if (reader.EndOfStream)
return new FileSegmentSearchResult(start,end);
lines = reader.SearchLines(_predicate, i => i, (line, position) =>
{
lastPosition = position;//this is end of line po
return end != -1 && lastPosition > end;
}).ToArray();
}
return new FileSegmentSearchResult(start, lastPosition, lines);
}
}
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);
}
}
}
/// <summary>
/// Finds the delimiter by looking for the first line in the file and comparing chars
/// </summary>
/// <param name="source">The source.</param>
/// <returns></returns>
public static int FindDelimiter(this FileInfo source)
{
using (var stream = File.Open(source.FullName, FileMode.Open, FileAccess.Read, FileShare.Delete | FileShare.ReadWrite))
{
using (var reader = new StreamReaderExtended(stream, Encoding.Default, true))
{
if (reader.EndOfStream)
return -1;
do
{
var ch = (char)reader.Read();
// Note the following common line feed chars:
// \n - UNIX \r\n - DOS \r - Mac
switch (ch)
{
case '\r':
var next = (char)reader.Peek();
//with \n is WINDOWS delimiter. Otherwise mac
return next == '\n' ? 2 : 1;
case '\n':
return 1;
}
} while (!reader.EndOfStream);
return -1;
}
}
}
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);
}
}
}
}
