/*                  /Net/dxcern/userd/timbl/hypertext/WWW/Library/Implementation/HTBTree.html
                         BALANCED BINARY TREE FOR SORTING THINGS

   Tree creation, traversal and freeing.  User-supplied comparison routine.

   Author: Arthur Secret, CERN. Public domain.  Please mail bugs and changes to
   www-request@info.cern.ch

   part of libWWW

 */
#ifndef HTBTREE_H
#define HTBTREE_H 1

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

Data structures

 */
typedef struct _HTBTree_element {
    void                        *object;        /* User object */
    struct _HTBTree_element     *up;
    struct _HTBTree_element     *left;
    int                         left_depth;
    struct _HTBTree_element     *right;
    int                         right_depth;
} HTBTElement;

typedef int (*HTComparer) PARAMS((void * a, void * b));

typedef struct _HTBTree_top {
    HTComparer                  compare;
    struct _HTBTree_element     *top;
} HTBTree;


/*

Create a binary tree given its discrimination routine

 */
extern HTBTree * HTBTree_new PARAMS((HTComparer comp));



/*

Free storage of the tree but not of the objects

 */
extern void HTBTree_free PARAMS((HTBTree* tree));



/*

Free storage of the tree and of the objects

 */
extern void HTBTreeAndObject_free PARAMS((HTBTree* tree));



/*

Add an object to a binary tree

 */

extern void HTBTree_add PARAMS((HTBTree* tree, void * object));


/*

Find user object for element

 */
#define HTBTree_object(element)  ((element)->object)


/*

Find next element in depth-first order

  ON ENTRY,

  ele                    if NULL, start with leftmost element. if != 0 give next object to
                         the right.

  returns                Pointer to element ot NULL if none left.

 */
extern HTBTElement * HTBTree_next PARAMS((HTBTree* tree, HTBTElement * ele));

#endif /* HTBTREE_H */