/*              List object
 *
 *      The list object is a generic container for storing collections
 *      of things in order.
 */
#ifndef HTLIST_H
#define HTLIST_H

#ifndef HTUTILS_H
#include <HTUtils.h>
#endif

#ifdef __cplusplus
extern "C" {
#endif
    typedef struct _HTList HTList;

    struct _HTList {
	void *object;
	HTList *next;
    };

/*	Fast macro to traverse a list.  Call it first with copy of the list
 *	header.  It returns the first object and increments the passed list
 *	pointer.  Call it with the same variable until it returns NULL.
 */
#define HTList_nextObject(me) \
	((me) && ((me) = (me)->next) ? (me)->object : NULL)

/*	Macro to find object pointed to by the head (returns NULL
 *	if list is empty, OR if it doesn't exist - Yuk!)
 */
#define HTList_lastObject(me) \
	((me) && (me)->next ? (me)->next->object : NULL)

/*	Macro to check if a list is empty (or doesn't exist - Yuk!)
*/
#define HTList_isEmpty(me) ((me) ? ((me)->next == NULL) : YES)

/*	Create list.
*/
    extern HTList *HTList_new(void);

/*	Delete list.
*/
    extern void HTList_delete(HTList *me);

/*	Reverse a list.
*/
    extern HTList *HTList_reverse(HTList *start);

/*	Append two lists, making second list empty.
*/
    extern HTList *HTList_appendList(HTList *start,
				     HTList *tail);

/*      Add object to START of list (so it is pointed to by the head).
*/
    extern void HTList_addObject(HTList *me,
				 void *newObject);

/*      Append object to END of list (furthest from the head).
*/
    extern void HTList_appendObject(HTList *me,
				    void *newObject);

/*	Insert an object into the list at a specified position.
 *      If position is 0, this places the object at the head of the list
 *      and is equivalent to HTList_addObject().
 */
    extern void HTList_insertObjectAt(HTList *me,
				      void *newObject,
				      int pos);

/*	Remove specified object from list.
*/
    extern BOOL HTList_removeObject(HTList *me,
				    void *oldObject);

/*	Remove object at a given position in the list, where 0 is the
 *	object pointed to by the head (returns a pointer to the element
 *	(->object) for the object, and NULL if the list is empty, or
 *	if it doesn't exist - Yuk!).
 */
    extern void *HTList_removeObjectAt(HTList *me,
				       int position);

/*	Remove object from START of list (the Last one inserted
 *	via HTList_addObject(), and pointed to by the head).
 */
    extern void *HTList_removeLastObject(HTList *me);

/*	Remove object from END of list (the First one inserted
 *	via HTList_addObject(), and furthest from the head).
 */
    extern void *HTList_removeFirstObject(HTList *me);

/*	Determine total number of objects in the list,
 *	not counting the head.
 */
    extern int HTList_count(HTList *me);

/*	Determine position of an object in the list (a value of 0
 *	means it is pointed to by the head; returns -1 if not found).
 */
    extern int HTList_indexOf(HTList *me,
			      void *object);

/*	Return pointer to the object at a specified position in the list,
 *	where 0 is the object pointed to by the head (returns NULL if
 *	the list is empty, or if it doesn't exist - Yuk!).
 */
    extern void *HTList_objectAt(HTList *me,
				 int position);

/*      Link object to START of list (so it is pointed to by the head).
 *
 *      Unlike HTList_addObject(), it does not malloc memory for HTList entry,
 *	it use already allocated memory which should not be free'd by any
 *	list operations (optimization).
 */
    extern void HTList_linkObject(HTList *me,
				  void *newObject,
				  HTList *newNode);

/*	Unlink object from START of list (the Last one inserted
 *	via HTList_linkObject(), and pointed to by the head).
 *	It does not free memory.
 */
    extern void *HTList_unlinkLastObject(HTList *me);

/*	Unlink specified object from list.
 *	It does not free memory.
 */
    extern BOOL HTList_unlinkObject(HTList *me,
				    void *oldObject);

#ifdef __cplusplus
}
#endif
#endif				/* HTLIST_H */