/*
 * Definition of a generic list.  The visible list functions are:
 *
 *	List NewList()
 *	PutList(List l, ListElem e)
 *	ListElem PullList(List l)
 *	PushList(List l, ListElem e)
 *	ListElem PopList(List l)
 *	ListElem GetNthList(List l, int n)
 *	ListElem DelNthList(List l, int n)
 * 	int ListLen(List l)
 * 	ListElem EnumList(List l)
 *	ResetListEnum(l)
 *	PrintList(list l)
 *
 *
 * List elements have the following opaque structure:
 *
 *	ListElem Data;
 *	List Next;
 *	List Prev;
 *
 */
#ifndef list_included
#define list_included
typedef char *ListElem;

typedef struct ListItemStruct {
    ListElem Data;
    struct ListItemStruct *Next;
    struct ListItemStruct *Prev;
} *ListItem;

typedef struct ListStruct {
    ListItem First;
    ListItem Last;
    int Size;
    ListItem EnumState;
} *List;

/*
 * Visible functions.
 */
List NewList();
PutList(/* List l, ListElem e */);
ListElem PullList(/* List l */);
PushList(/* List l, ListElem e */);
ListElem PopList(/* List l */);
ListElem GetNthList(/* List l, int n */);
ListElem DelNthList(/* List l, int n */);
int ListLen(/* List l */);
ListElem EnumList(/* List l */);
ResetListEnum(/* l */);
PrintList(/* list l */);
#endif