// TODO: empty values might not be handled correctly
// (e.g. a,,c)
sclass ExtendedCSVParser {
  S csv;
  int numFields;
  
  *() {}
  *(S *csv) {}
  
  run {
    int i = 0, startOfValue = 0;
    bool inQuotedValue;
    while ping (i < l(csv)) {
      char c = csv.charAt(i);
      if (c == ',') {
        foundValue(substring(csv, startOfValue, i));
        startOfValue = i+1;
      } else if (c == '\r' || c == '\n') {
        if (!inQuotedValue) {
          foundValue(substring(csv, startOfValue, i));
          startOfValue = i+1;
          endOfRecord();
        }
      } else if (c == '"') {
        if (inQuotedValue) {
          if (charAt(csv, i+1) == '"') i++; // double quotes inside of a value
          else
            inQuotedValue = false;
        } else
          set inQuotedValue;
      }
      i++;
    }
    foundValue(substring(csv, startOfValue));
    endOfRecord();
  }
  
  S unquoteValue(S value) {
    ret dropPrefix("\"", dropSuffix("\"", replace(trim(value), "\"\"", "\"")));
  }
  
  void foundValue(S value) {
    if (nempty(value)) {
      ++numFields;
      onValueFound(unquoteValue(value));
    }
  }
  
  void endOfRecord {
    if (numFields != 0) onEndOfRecord();
    numFields = 0;
  }
  
  swappable void onValueFound(S value) {}
  swappable void onEndOfRecord() {}
}