Move CsvIndexer and CsvParser to CsvLib project.

CsvLib/CsvIndexer.cs

@@ -0,0 +1,137 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+
+namespace CsvLib
+{
+    public class CsvIndexer
+    {
+        private bool _insideString;
+
+        private readonly char _separator;
+        private readonly char _quoteChar;
+        private readonly char _escapeChar;
+
+        public CsvIndexer(char separator = ',', char quoteChar = '"', char escapeChar = '\\')
+        {
+            _separator = separator;
+            _quoteChar = quoteChar;
+            _escapeChar = escapeChar;
+        }
+
+        private List<long> _index = new List<long>();
+
+        public List<long> Index { get { return _index; } }
+
+        private void DummyParser(string line)
+        {
+            for (int i = 0; i < line.Length; i++)
+            {
+                char c = line[i];
+                if (c == _separator && _insideString == false)
+                {
+                    continue;
+                }
+                if (c == _quoteChar && _insideString == false)
+                {
+                    _insideString = true;
+                    continue;
+                }
+                if (c == _quoteChar && _insideString)
+                {
+                    _insideString = false;
+                    continue;
+                }
+                if (c == _escapeChar && _insideString)
+                {
+                    i++;
+                    c = line[i];
+                }
+            }
+        }
+
+        public void GenerateIndex(string file)
+        {
+            _insideString = false;
+            _index.Clear();
+            using (FileStream stream = new FileStream(file, FileMode.Open))
+            using (StreamReader streamReader = new StreamReader(stream, Encoding.Default, true, 4096))
+            using (TrackingTextReader reader = new TrackingTextReader(streamReader))
+            {
+                string currentLine;
+                if (_insideString == false)
+                {
+                    _index.Add(reader.Position);
+                }
+                while ((currentLine = reader.ReadLine()) != null)
+                {
+                    DummyParser(currentLine);
+                    if (_insideString == false)
+                    {
+                        _index.Add(reader.Position);
+                    }
+                }
+            }
+        }
+
+        private void Index_SaveFile(string indexFile)
+        {
+            if (File.Exists(indexFile))
+            {
+                File.Delete(indexFile);
+            }
+            Stream streamOut = File.Open(indexFile, FileMode.Create);
+            using (BinaryWriter binWriter = new BinaryWriter(streamOut))
+            {
+                binWriter.Write(_index.Count);
+                for (int i = 0; i < _index.Count; i++)
+                {
+                    binWriter.Write(_index[i]);
+                }
+            }
+            streamOut.Close();
+        }
+
+        private static List<long> Index_LoadFile(string indexFile)
+        {
+            List<long> tempIndex = new List<long>();
+
+            Stream streamIn = File.Open(indexFile, FileMode.Open);
+            using (BinaryReader binReader = new BinaryReader(streamIn))
+            {
+                int numRegs = binReader.ReadInt32();
+                for (int i = 0; i < numRegs; i++)
+                {
+                    long value = binReader.ReadInt64();
+                    tempIndex.Add(value);
+                }
+            }
+            streamIn.Close();
+            return tempIndex;
+        }
+
+        public void LoadIndexOfFile(string file)
+        {
+            DateTime dtFile = File.GetCreationTime(file);
+            string indexFile = $"{file}.idx";
+            if (File.Exists(indexFile) && File.GetCreationTime(indexFile) > dtFile)
+            {
+                _index = Index_LoadFile(indexFile);
+            }
+            else
+            {
+                // Generate index
+                DateTime dtNow = DateTime.UtcNow;
+                GenerateIndex(file);
+                TimeSpan tsGenIndex = DateTime.UtcNow - dtNow;
+                
+                // Save Index if expensive generation
+                if (tsGenIndex.TotalSeconds > 2)
+                {
+                    Index_SaveFile(indexFile);
+                }
+            }
+        }
+    }
+}