CSV to JSON stream converter. Use: mono CSVtoJSON.exe "input.csv" "output.json" "optional:delimiter"

gistfile1.cs

using System;
using System.Text;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using System.Text.RegularExpressions;

namespace CSVtoJSON
{
	class MainClass
	{
		protected static int origRow;
		protected static int origCol;

		protected static void WriteAt (string s, int x, int y)
		{
			try {
				Console.SetCursorPosition (origCol + x, origRow + y);
				Console.Write (s);
			} catch (ArgumentOutOfRangeException e) {
				Console.Clear ();
				Console.WriteLine (e.Message);
			}
		}

		public static List<String> qLines (string input, string delimiter = ",")
		{
			if (input == null)
				throw new ArgumentNullException ("Must have data");
			var result = new List<String> ();
			var pattern = new Regex (@"
				\s*                      # Ignore leading whitespace.
				(?:                      # Group of value alternatives.
				""                     # Either a double quoted string,
				(?<val>                # Capture contents between quotes.
				[^""]*(""""[^""]*)*  # Zero or more non-quotes, allowing 
				)                      # doubled "" quotes within string.
				""\s*                  # Ignore whitespace following quote.
				|  (?<val>[^" + delimiter +
				@"]*)         			 # Or... zero or more non-delimiter.
				)                        # End value alternatives group.
				(?:" + delimiter + "|$)	 # Match end is delimiter or EOS", 
				RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace);
			try {
				var matchResult = pattern.Match (input);
				while (matchResult.Success) {
					result.Add (matchResult.Groups ["val"].Value);
					matchResult = matchResult.NextMatch ();
				} 
			} catch (ArgumentException ex) {
				throw ex;
			}
			result.Remove ("");
			return result;
		}

		public static void StreamConvertCSVtoJSON (string pathIn, string pathOut, string delimiter = ",")
		{
			var isCommaTime = false;
			var i = 0;
			var j = 0;
			try {
				if (File.Exists (pathOut)) 
					File.Delete (pathOut);

				using (StreamWriter sw = new StreamWriter(new FileStream(
					pathOut, FileMode.CreateNew, FileAccess.ReadWrite),Encoding.UTF8))
				using (StreamReader sr = new StreamReader(new FileStream(
					pathIn, FileMode.Open, FileAccess.Read), Encoding.UTF8)) {
					if (sr.Peek () < 0)
						return;
					var headers = qLines (sr.ReadLine (), delimiter);
					sw.WriteLine ("[");
					while (sr.Peek() >= 0) { 
						var fields = qLines (sr.ReadLine (), delimiter);
						if (fields.Count != headers.Count)
							i++;
						else
							j++;
						var jsonElements = headers.Zip (
							fields, 
							(header, field) => string.Format (
							"\"{0}\": \"{1}\"", header, fieldFix (field))).ToArray ();
						string jsonObject = "{" + string.Format (
							"{0}", string.Join (",", jsonElements)) + "}";
						if (isCommaTime)
							jsonObject = "," + jsonObject;
						sw.WriteLine (jsonObject);
						isCommaTime = true;
						if ((i + j) % 1000 == 0) 
							progressUpdate (i, j);
					}
					sw.WriteLine ("]");
					progressUpdate (i, j);
				}
			} catch (Exception e) {
				throw new Exception (string.Format ("The process failed: {0}", e.ToString ()));
			}
		}

		private static string fieldFix (string vars)
		{
			return vars.Replace ("\"", "'");
		}

		public static void progressUpdate (int i, int j)
		{
			WriteAt ("" + j + " successful lines.", 0, 0);
			WriteAt ("" + i + " warning(s): Field count does not match header count.", 0, 1);
			WriteAt ("", 0, 2);
		}

		public static void Main (string[] args)
		{
			origRow = Console.CursorTop;
			origCol = Console.CursorLeft;
			if (args.Length < 2) {
				Console.WriteLine ("Use: mono CSVtoJSON.exe \"input.csv\" \"output.json\" \"optional:delimiter\"");
				return;
			} 
			if (args.Length == 2) {
				StreamConvertCSVtoJSON (args [0], args [1]);
			} else {
				StreamConvertCSVtoJSON (args [0], args [1], args [2]);
			}
		}
	}
}