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CrowdControl/Assets/BuildReport/Scripts/Editor/Utility/DldUtil_BackwardFileReader.cs

94 lines
1.8 KiB
C#

using System.IO;
using System.Text;
namespace DldUtil
{
// from http://arstechnica.com/civis/viewtopic.php?p=22839293&sid=e2bcb348ac8b58c9016e6a0a6442ba1b#p22839293
public class BackwardReader
{
readonly FileStream fs;
public BackwardReader(string path)
{
fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
}
public void JumpToEnd(long lineNumber)
{
fs.Seek(0, SeekOrigin.End);
}
public void JumpToLine(long lineNumber)
{
fs.Seek(lineNumber, SeekOrigin.Begin);
}
public string ReadLine()
{
var text = new byte[1];
long position = 0;
fs.Seek(0, SeekOrigin.Current);
position = fs.Position;
// do we have a trailing \r\n?
if (fs.Length > 1)
{
var vagnretur = new byte[2];
fs.Seek(-2, SeekOrigin.Current);
fs.Read(vagnretur, 0, 2);
if (Encoding.ASCII.GetString(vagnretur).Equals("\r\n"))
{
// move it back
fs.Seek(-2, SeekOrigin.Current);
position = fs.Position;
}
}
while (fs.Position > 0)
{
text.Initialize();
// read one char
fs.Read(text, 0, 1);
var asciiText = Encoding.ASCII.GetString(text);
// move back to the character before
fs.Seek(-2, SeekOrigin.Current);
if (asciiText.Equals("\n"))
{
fs.Read(text, 0, 1);
asciiText = Encoding.ASCII.GetString(text);
if (asciiText.Equals("\r"))
{
fs.Seek(1, SeekOrigin.Current);
break;
}
}
}
var count = int.Parse((position - fs.Position).ToString());
var line = new byte[count];
fs.Read(line, 0, count);
fs.Seek(-count, SeekOrigin.Current);
return Encoding.ASCII.GetString(line);
}
public bool SOF
{
get { return fs.Position == 0; }
}
public void Close()
{
fs.Close();
}
}
}