/* A class representing a forward-linked list of strings. This code contains
 * several serious errors, so don't use it as a reference!
 */
class ForwardList
{
public:
  /**
   * Constructor: ForwardList(numElems, defaultValue)
   * Usage: ForwardList myList(10); // Contains ten copies of the empty string
   * Usage: ForwardList myList(10, "Hello!"); // Contains ten copies of "Hello!"
   * -------------------------------------------------------------------
   * Constructs a new list of the specified size where each element is
   * initialized to the specified value. If no size is specified, defaults to
   * zero. If no default value is specified, the empty string is used.
   */
  ForwardList(int numElems = 0, string defaultValue = "");
  
  /**
   * Constructor: ForwardList(vector<string>::iterator begin,
   * vector<string>::iterator end);
   * Usage: ForwardList myList(v.begin(), v.end());
   * ---------------------------------------------------------------------
   * Constructs a new list whose elements are equal to those specified by
   * the input pair of vector<string>::iterators.
   */
  ForwardList(vector<string>::iterator begin, vector<string>::iterator end);
  
  /**
   * Destructor: ~ForwardList();
   * Usage: delete myListPtr;
   * ---------------------------------------------------------------------
   * Cleans up any memory allocated by this ForwardList object.
   */
  ~ForwardList();
  
  /**
   * Type: iterator
   * ---------------------------------------------------------------------
   * A forward iterator that can read and write values stored in the
   * ForwardList.
   */
  typedef something-implementation-specific iterator;
  
  /**
   * Functions begin() and end()
   * Usage: for(ForwardList::iterator itr = l.begin(); itr != l.end(); ++itr)
   * ----------------------------------------------------------------------
   * Returns iterators to the first element in the list and the first element
   * past the end of the list, respectively.
   */
  iterator begin();
  iterator end();

  /**
   * Functions: push_front(val), pop_front(), front()
   * Usage: v.push_front("This is a string!"); s = v.front(); v.pop_front();
   * ----------------------------------------------------------------------
   * push_front prepends the specified element to the linked list,
   * increasing its size by one. pop_front removes the first element of the
   * list without returning its value; use front() before calling pop_front()
   * if you want to retrieve the value.
   *
   * front() returns a reference to the first element in the list, so it's
   * legal to write either val = front() or front() = val.
   */
  void push_front(string value);
  void pop_front();
  string& front();
  
  /**
   * Functions: empty(), size()
   * Usage: if(v.empty()) ... if(v.size() > 10) ...
   * -----------------------------------------------------------------------
   * empty() returns whether the list is empty (i.e. begin() == end()).
   * size() returns the number of elements stored in the list.
   */
  bool empty();
  int size();
private:
  /* ... implementation details ... */
};