cvsreader.cs

VWAP image analysis for stock system

using System;
using System.Collections;
using System.IO;
using System.Text;


	/// <summary>
	/// A data-reader style interface for reading CSV files.
	/// </summary>
	public class CSVReader : IDisposable 
	{

		#region Private variables

		private Stream stream;
		private StreamReader reader;

		#endregion

		/// <summary>
		/// Create a new reader for the given stream.
		/// </summary>
		/// <param name="s">The stream to read the CSV from.</param>
		public CSVReader(Stream s) : this(s, null) { }

		/// <summary>
		/// Create a new reader for the given stream and encoding.
		/// </summary>
		/// <param name="s">The stream to read the CSV from.</param>
		/// <param name="enc">The encoding used.</param>
		public CSVReader(Stream s, Encoding enc) 
		{

			this.stream = s;
			if (!s.CanRead) 
			{
				throw new CSVReaderException("Could not read the given CSV stream!");
			}
			reader = (enc != null) ? new StreamReader(s, enc) : new StreamReader(s);
		}

		/// <summary>
		/// Creates a new reader for the given text file path.
		/// </summary>
		/// <param name="filename">The name of the file to be read.</param>
		public CSVReader(string filename) : this(filename, null) { }

		/// <summary>
		/// Creates a new reader for the given text file path and encoding.
		/// </summary>
		/// <param name="filename">The name of the file to be read.</param>
		/// <param name="enc">The encoding used.</param>
		public CSVReader(string filename, Encoding enc) 
			: this(new FileStream(filename, FileMode.Open), enc) { }

		/// <summary>
		/// Returns the fields for the next row of CSV data (or null if at eof)
		/// </summary>
		/// <returns>A string array of fields or null if at the end of file.</returns>
		public string[] GetCSVLine() 
		{

			string data = reader.ReadLine();
			if (data == null) return null;
			if (data.Length == 0) return new string[0];
      
			ArrayList result = new ArrayList();

			ParseCSVFields(result, data);
      
			return (string[])result.ToArray(typeof(string));
		}

		// Parses the CSV fields and pushes the fields into the result arraylist
		private void ParseCSVFields(ArrayList result, string data) 
		{

			int pos = -1;
			while (pos < data.Length)
				result.Add(ParseCSVField(data, ref pos));
		}

		// Parses the field at the given position of the data, modified pos to match
		// the first unparsed position and returns the parsed field
		private string ParseCSVField(string data, ref int startSeparatorPosition) 
		{

			if (startSeparatorPosition == data.Length-1) 
			{
				startSeparatorPosition++;
				// The last field is empty
				return "";
			}

			int fromPos = startSeparatorPosition + 1;

			// Determine if this is a quoted field
			if (data[fromPos] == '"') 
			{
				// If we're at the end of the string, let's consider this a field that
				// only contains the quote
				if (fromPos == data.Length-1) 
				{
					fromPos++;
					return "\"";
				}

				// Otherwise, return a string of appropriate length with double quotes collapsed
				// Note that FSQ returns data.Length if no single quote was found
				int nextSingleQuote = FindSingleQuote(data, fromPos+1);
				startSeparatorPosition = nextSingleQuote+1;
				return data.Substring(fromPos+1, nextSingleQuote-fromPos-1).Replace("\"\"", "\"");
			}

			// The field ends in the next comma or EOL
			int nextComma = data.IndexOf(',', fromPos);
			if (nextComma == -1) 
			{
				startSeparatorPosition = data.Length;
				return data.Substring(fromPos);
			}
			else 
			{
				startSeparatorPosition = nextComma;
				return data.Substring(fromPos, nextComma-fromPos);
			}
		}

		// Returns the index of the next single quote mark in the string 
		// (starting from startFrom)
		private int FindSingleQuote(string data, int startFrom) 
		{

			int i = startFrom-1;
			while (++i < data.Length)
				if (data[i] == '"') 
				{
					// If this is a double quote, bypass the chars
					if (i < data.Length-1 && data[i+1] == '"') 
					{
						i++;
						continue;
					}
					else
						return i;
				}
			// If no quote found, return the end value of i (data.Length)
			return i;
		}

		/// <summary>
		/// Disposes the CSVReader. The underlying stream is closed.
		/// </summary>
		public void Dispose() 
		{
			// Closing the reader closes the underlying stream, too
			if (reader != null) reader.Close();
			else if (stream != null)
				stream.Close(); // In case we failed before the reader was constructed
			GC.SuppressFinalize(this);
		}
	}


	/// <summary>
	/// Exception class for CSVReader exceptions.
	/// </summary>
	public class CSVReaderException : ApplicationException 
	{ 
  
		/// <summary>
		/// Constructs a new exception object with the given message.
		/// </summary>
		/// <param name="message">The exception message.</param>
		public CSVReaderException(string message) : base(message) { }
	}