/* Header file for library implementing double-linked lists.
 * Authors: Dmitry Krivin
 *          Oleksiy Andriychenko
 *          Prashant Paroda
 *          D. Hawando
 *
 * Dear Sam,
 *
 *   In order to get full credit for this assignment, 
 * we have implemented a lot of different and interesting
 * methods for operating the lists, including all the basic
 * methods (adding, deleting, displaying, length), 
 * iterating the list, sorting, searching and appending
 * the lists, and even duplicating lists. In addition, our quicksort
 * pics random pivot and takes a function for comparison as a 
 * parameter. Also, we have used wrapper structure to protect
 * users from directly messing up with implementation. 
 * 
 * Have fun reading this. Hope you'll enjoy our program.
 * 
 * Sincerely,
 * 
 *    - Authors.
 */

typedef struct list* Listptr;


Listptr createlist ();
int isempty (Listptr mylist);
int length (Listptr mylist);
void addtofront (Listptr mylist, char *contents);
void addtoend(Listptr mylist, char *contents);
int deletehead (Listptr mylist);
int deletetail (Listptr mylist);
void resettohead(Listptr mylist);
void resettotail(Listptr mylist);
int placecursor (Listptr mylist,int position);
int retreat(Listptr mylist);
int advance(Listptr mylist);
void addaftercursor(Listptr mylist, char *contents);
int deletecurrent (Listptr mylist);
void destroylist(Listptr mylist);
Listptr duplicate(Listptr mylist);
char *getcurrent(Listptr mylist);
int changecurrent(Listptr mylist, char *contents);
int writetofile (Listptr mylist, char *filename);
void writetoscreen (Listptr mylist);
Listptr readfromfile (char *filename);
int find(Listptr mylist, char *elem);
void append(Listptr first, Listptr second);
void quicksort(Listptr mylist, int (*compar)(char *,char *));