/***********************************************************************/
/*                        String List Interface                        */
/***********************************************************************/
/* A minimal implementation of linked lists.                           */
/* Author:  Mark A. Sheldon, Tufts University, Fall 2012               */
/*                                                                     */
/* An StringList is either:                                            */
/*      - An empty list (the empty list)  OR                           */
/*      - A non-empty list node containing:                            */
/*           o a string-valued first element  AND                      */
/*           o a StringList for the rest of the elements               */
/*                                                                     */
/* Operations:                                                         */
/* (see prototypes below for parameter/type information)               */
/*      empty()      : returns an empty list                           */
/*      isEmpty()    : returns true if the given list is empty,        */
/*                     and false otherwise                             */
/*      prepend()    : returns a newly allocated list node with the    */
/*                     given data value as the first element and the   */
/*                     given list as the rest                          */
/*      first()       : returns the first data value in the given      */
/*                     non-empty list node.                            */
/*                     It is an error to pass first() an empty list.   */
/*      rest()       : returns the IntList containing all the elements */
/*                     except the first one in the given non-empty     */
/*                     list.                                           */
/*                     It is an error to call rest() on an empty list. */
/*      deleteFirst() : returns the IntList that rest() would.         */
/*                     Frees storage associated with the first node  . */
/*                     It is an error to call deleteFirst() on an      */
/*                     empty list.                                     */
/***********************************************************************/

#ifndef __STRINGLIST_H__
#define __STRINGLIST_H__

#include <string>

using std::string;

struct  StringListNode;

StringListNode *empty      (void);
bool            isEmpty    (StringListNode *list);
StringListNode *prepend    (string new_data, StringListNode *list);
string          first      (StringListNode *list);
StringListNode *rest       (StringListNode *list);
StringListNode *deleteFirst(StringListNode *list);

void            deleteAfter(StringListNode *list);

#endif