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/*                  /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
   
 */

#ifdef SHORT_NAMES
#define HTBTree_new             HTBTNew
#define HTBTree_free            HTBTFree
#define HTBTreeAndObject_free   HTBTAOFr
#define HTBTree_add             HTBTAdd
#define HTBTree_next            HTBTNext
/* #define      HTBTree_object          HTBTObje already a macro */
#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));

/*

   end  */