/* teht8_2.cpp M 2.30.2 */
/*
         2) Toteuta list "oikeana" dynaamisena listana.
*/

#include <iostream.h>

#define TYPE char
class list;

class elem {
  friend list;
  TYPE data;
  elem *next_elem;
  elem(TYPE d)  { data = d; next_elem = NULL; }
  int add(elem *n) { next_elem = n; return 0; }
};


class list {
protected:
  elem *first_elem;
  elem *last_elem;
  elem *cursor;          // Sijainti listassa
  TYPE out_data;
  int no_elem()    { first_elem = last_elem = cursor = NULL; out_data = 0;
                     return 0;                                               }
public:
  int delete_all();
  list()           { no_elem();                                              }
  ~list()          { delete_all();                                           }

  int  out()       { return ( cursor == NULL );                              }
  int  tobegin()   { cursor = first_elem;   return out();                    }
  int  forward()   { if ( !cursor ) return 1;
                     out_data = cursor->data;
                     cursor = cursor->next_elem; return 0;                   }
  int  toend()     { cursor = last_elem; return out();                       }
  TYPE current()   { return cursor ? cursor->data : out_data;                }
  TYPE first()     { tobegin(); return current();                            }
  TYPE next()      { forward(); return current();                            }
  TYPE last()      { toend();   return current();                            }
  int  empty()     { return ( first_elem == NULL );                          }
  int  add(TYPE p) { elem *n = new elem(p);
                     if ( !n ) return 1;
                     if ( first_elem ) last_elem->add(n);
                     else first_elem = n;
                     last_elem = n; return 0;
                   }
}; /* list */

int list::delete_all()
{
  elem *e;
  tobegin();
  while ( cursor ) { e = cursor; forward(); delete e; }
  return no_elem();
}

#define VIIVA "------------------------------------------------------------\n"
/****************************************************************************/
int main(void)
{
  cout << VIIVA;

  list lc; lc.add('a'); lc.add('b'); lc.add('c'); lc.add('d');

  for (char c=lc.first(); !lc.out(); c=lc.next() )
    cout << c << " ";

  cout << c << "\n" << VIIVA;

  for (lc.tobegin(); !lc.out(); lc.forward() )
    cout << lc.current() << " ";

  cout << lc.current() << "\n" << VIIVA;

  return 0;
}