private static string[] ParseCsv(TextReader reader, ref int lineNum, char separator)
{
var curChar = CharReader.Create(reader);
if (curChar.IsEof)
{
return(null); // EOF reached
}
if (curChar.IsEol)
{
lineNum++;
#if !FW452
return(Array.Empty <string>());
#else
return(Array <string> .Empty);
#endif
}
var result = new List <string>();
StringBuilder curField = null;
var state = ParserState.ExpectField;
var column = 1;
while (true)
{
var skip = false;
while (!skip)
{
switch (state)
{
case ParserState.ExpectField:
if (curChar.IsEof || curChar.IsEol)
{
if (result.Count > 0) // Special case - empty string not treated as single empty value
{
result.Add("");
}
return(result.ToArray());
}
if (curChar.Char == separator)
{
result.Add("");
state = ParserState.AfterField;
break;
}
skip = true;
if (curChar.IsWhitespace)
{
break;
}
curField = new StringBuilder();
if (curChar.IsDoubleQuota)
{
state = ParserState.QuotedField;
break;
}
state = ParserState.Field;
curField.Append(curChar.Char);
break;
case ParserState.Field:
Debug.Assert(curField != null, "curField != null");
if (curChar.IsEof || curChar.IsEol || curChar.Char == separator)
{
result.Add(curField.ToString().Trim());
state = ParserState.AfterField;
break;
}
skip = true;
curField.Append(curChar.Char);
break;
case ParserState.QuotedField:
Debug.Assert(curField != null, "curField != null");
if (curChar.IsEof)
{
throw new FormatException($"Unexpected EOF at line {lineNum} column {column}");
}
skip = true;
if (curChar.IsEol)
{
curField.Append("\r\n");
break;
}
if (curChar.IsDoubleQuota)
{
var peek = curChar.Peek();
if (peek.IsDoubleQuota) // Escaped '"'
{
curField.Append('"');
curChar = curChar.Next();
}
else
{
result.Add(curField.ToString());
state = ParserState.AfterField;
}
break;
}
curField.Append(curChar.Char);
break;
case ParserState.AfterField:
if (curChar.IsEof || curChar.IsEol)
{
return(result.ToArray());
}
skip = true;
if (curChar.IsWhitespace)
{
continue;
}
if (curChar.Char == separator)
{
state = ParserState.ExpectField;
break;
}
throw new FormatException($"Unexpected char '{curChar.Char}' at line {lineNum} column {column}");
default:
throw new ArgumentOutOfRangeException();
}
}
curChar = curChar.Next();
column++;
if (curChar.IsEol)
{
lineNum++;
column = 1;
}
}
}