Cpp code to parse CSV files

csv_reader.cpp

/* Usage:
* std::ifstream file("plop.csv");
*  for(CSVIterator loop(file); loop != CSVIterator(); ++loop)
*  {
*      std::cout << "4th Element(" << (*loop)[3] << ")\n";
*  }
*/
class CSVIterator {
 private:
  class CSVRow {
   public:
    std::string const& operator[](std::size_t index) const {
      return m_data[index];
    }
    std::size_t size() const { return m_data.size(); }
    void readNextRow(std::istream& str) {
      std::string line;
      std::getline(str, line);

      std::stringstream lineStream(line);
      std::string cell;

      m_data.clear();
      while (std::getline(lineStream, cell, ',')) {
        m_data.push_back(cell);
      }
      // This checks for a trailing comma with no data after it.
      if (!lineStream && cell.empty()) {
        // If there was a trailing comma then add an empty element.
        m_data.push_back("");
      }
    }

   private:
    std::vector<std::string> m_data;
  };

  friend std::istream& operator>>(std::istream& str, CSVRow& data) {
    data.readNextRow(str);
    return str;
  }

 public:
  typedef std::input_iterator_tag iterator_category;
  typedef CSVRow value_type;
  typedef std::size_t difference_type;
  typedef CSVRow* pointer;
  typedef CSVRow& reference;

  CSVIterator(std::istream& str) : m_str(str.good() ? &str : NULL) {
    ++(*this);
  }
  CSVIterator() : m_str(NULL) {}

  // Pre Increment
  CSVIterator& operator++() {
    if (m_str) {
      if (!((*m_str) >> m_row)) {
        m_str = NULL;
      }
    }
    return *this;
  }
  // Post increment
  CSVIterator operator++(int) {
    CSVIterator tmp(*this);
    ++(*this);
    return tmp;
  }
  CSVRow const& operator*() const { return m_row; }
  CSVRow const* operator->() const { return &m_row; }

  bool operator==(CSVIterator const& rhs) {
    return ((this == &rhs) || ((this->m_str == NULL) && (rhs.m_str == NULL)));
  }
  bool operator!=(CSVIterator const& rhs) { return !((*this) == rhs); }

 private:
  std::istream* m_str;
  CSVRow m_row;
};