1 /* avl.c - routines to implement an avl tree */
3 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
5 * Copyright 1998-2007 The OpenLDAP Foundation.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted only as authorized by the OpenLDAP
12 * A copy of this license is available in the file LICENSE in the
13 * top-level directory of the distribution or, alternatively, at
14 * <http://www.OpenLDAP.org/license.html>.
16 /* Portions Copyright (c) 1993 Regents of the University of Michigan.
17 * All rights reserved.
19 * Redistribution and use in source and binary forms are permitted
20 * provided that this notice is preserved and that due credit is given
21 * to the University of Michigan at Ann Arbor. The name of the University
22 * may not be used to endorse or promote products derived from this
23 * software without specific prior written permission. This software
24 * is provided ``as is'' without express or implied warranty.
27 * This work was originally developed by the University of Michigan
28 * (as part of U-MICH LDAP). Additional significant contributors
31 * Hallvard B. Furuseth
38 #include <ac/stdlib.h>
41 #define ber_memalloc malloc
42 #define ber_memrealloc realloc
43 #define ber_memfree free
51 static const int avl_bfs[] = {LH, RH};
54 * avl_insert -- insert a node containing data data into the avl tree
55 * with root root. fcmp is a function to call to compare the data portion
56 * of two nodes. it should take two arguments and return <, >, or == 0,
57 * depending on whether its first argument is <, >, or == its second
58 * argument (like strcmp, e.g.). fdup is a function to call when a duplicate
59 * node is inserted. it should return 0, or -1 and its return value
60 * will be the return value from avl_insert in the case of a duplicate node.
61 * the function will be called with the original node's data as its first
62 * argument and with the incoming duplicate node's data as its second
63 * argument. this could be used, for example, to keep a count with each
66 * NOTE: this routine may malloc memory
69 avl_insert( Avlnode ** root, void *data, AVL_CMP fcmp, AVL_DUP fdup )
71 Avlnode *t, *p, *s, *q, *r;
74 if ( *root == NULL ) {
75 if (( r = (Avlnode *) ber_memalloc( sizeof( Avlnode ))) == NULL ) {
78 r->avl_link[0] = r->avl_link[1] = NULL;
89 /* find insertion point */
91 cmp = fcmp( data, p->avl_data );
93 return (*fdup)( p->avl_data, data );
99 if (( q = (Avlnode *) ber_memalloc( sizeof( Avlnode ))) == NULL ) {
102 q->avl_link[0] = q->avl_link[1] = NULL;
106 p->avl_link[cmp] = q;
108 } else if ( q->avl_bf ) {
115 /* adjust balance factors */
116 cmp = fcmp( data, s->avl_data ) > 0;
117 r = p = s->avl_link[cmp];
121 cmp = fcmp( data, p->avl_data ) > 0;
122 p->avl_bf = avl_bfs[cmp];
123 p = p->avl_link[cmp];
126 /* checks and balances */
128 if ( s->avl_bf == EH ) {
131 } else if ( s->avl_bf == -a ) {
134 } else if ( s->avl_bf == a ) {
137 if ( r->avl_bf == a ) {
138 /* single rotation */
140 s->avl_link[cmp] = r->avl_link[ncmp];
141 r->avl_link[ncmp] = s;
144 } else if ( r->avl_bf == -a ) {
145 /* double rotation */
146 p = r->avl_link[ncmp];
147 r->avl_link[ncmp] = p->avl_link[cmp];
148 p->avl_link[cmp] = r;
149 s->avl_link[cmp] = p->avl_link[ncmp];
150 p->avl_link[ncmp] = s;
152 if ( p->avl_bf == a ) {
155 } else if ( p->avl_bf == -a ) {
167 else if ( s == t->avl_right )
177 avl_delete( Avlnode **root, void* data, AVL_CMP fcmp )
179 Avlnode *p, *q, *r, *top;
180 int side, side_bf, shorter, nside;
183 Avlnode *pptr[sizeof(void *)*8];
184 unsigned char pdir[sizeof(void *)*8];
193 side = fcmp( data, p->avl_data );
200 p = p->avl_link[side];
206 /* If this node has two children, swap so we are deleting a node with
209 if ( p->avl_link[0] && p->avl_link[1] ) {
211 /* find the immediate predecessor <q> */
215 while (q->avl_link[1]) {
222 p->avl_link[0] = q->avl_link[0];
225 q->avl_link[1] = p->avl_link[1];
226 p->avl_link[1] = NULL;
228 q->avl_bf = p->avl_bf;
230 /* fix stack positions: old parent of p points to q */
234 r->avl_link[pdir[side-1]] = q;
238 /* new parent of p points to p */
239 if ( depth-side > 1 ) {
247 /* now <p> has at most one child, get it */
248 q = p->avl_link[0] ? p->avl_link[0] : p->avl_link[1];
257 /* set the child into p's parent */
261 p->avl_link[side] = q;
270 side_bf = avl_bfs[side];
272 /* case 1: height unchanged */
273 if ( p->avl_bf == EH ) {
274 /* Tree is now heavier on opposite side */
275 p->avl_bf = avl_bfs[nside];
278 } else if ( p->avl_bf == side_bf ) {
279 /* case 2: taller subtree shortened, height reduced */
282 /* case 3: shorter subtree shortened */
284 top = pptr[depth-1]; /* p->parent; */
287 /* set <q> to the taller of the two subtrees of <p> */
288 q = p->avl_link[nside];
289 if ( q->avl_bf == EH ) {
290 /* case 3a: height unchanged, single rotate */
291 p->avl_link[nside] = q->avl_link[side];
292 q->avl_link[side] = p;
295 p->avl_bf = (- side_bf);
297 } else if ( q->avl_bf == p->avl_bf ) {
298 /* case 3b: height reduced, single rotate */
299 p->avl_link[nside] = q->avl_link[side];
300 q->avl_link[side] = p;
306 /* case 3c: height reduced, balance factors opposite */
307 r = q->avl_link[side];
308 q->avl_link[side] = r->avl_link[nside];
309 r->avl_link[nside] = q;
311 p->avl_link[nside] = r->avl_link[side];
312 r->avl_link[side] = p;
314 if ( r->avl_bf == side_bf ) {
315 q->avl_bf = (- side_bf);
317 } else if ( r->avl_bf == (- side_bf)) {
327 /* a rotation has caused <q> (or <r> in case 3c) to become
328 * the root. let <p>'s former parent know this.
332 } else if (top->avl_link[0] == p) {
333 top->avl_link[0] = q;
335 top->avl_link[1] = q;
343 } /* end while(shorter) */
349 avl_inapply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag )
352 return( AVL_NOMORE );
354 if ( root->avl_left != 0 )
355 if ( avl_inapply( root->avl_left, fn, arg, stopflag )
359 if ( (*fn)( root->avl_data, arg ) == stopflag )
362 if ( root->avl_right == 0 )
363 return( AVL_NOMORE );
365 return( avl_inapply( root->avl_right, fn, arg, stopflag ) );
369 avl_postapply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag )
372 return( AVL_NOMORE );
374 if ( root->avl_left != 0 )
375 if ( avl_postapply( root->avl_left, fn, arg, stopflag )
379 if ( root->avl_right != 0 )
380 if ( avl_postapply( root->avl_right, fn, arg, stopflag )
384 return( (*fn)( root->avl_data, arg ) );
388 avl_preapply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag )
391 return( AVL_NOMORE );
393 if ( (*fn)( root->avl_data, arg ) == stopflag )
396 if ( root->avl_left != 0 )
397 if ( avl_preapply( root->avl_left, fn, arg, stopflag )
401 if ( root->avl_right == 0 )
402 return( AVL_NOMORE );
404 return( avl_preapply( root->avl_right, fn, arg, stopflag ) );
408 * avl_apply -- avl tree root is traversed, function fn is called with
409 * arguments arg and the data portion of each node. if fn returns stopflag,
410 * the traversal is cut short, otherwise it continues. Do not use -6 as
411 * a stopflag, as this is what is used to indicate the traversal ran out
416 avl_apply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag, int type )
420 return( avl_inapply( root, fn, arg, stopflag ) );
422 return( avl_preapply( root, fn, arg, stopflag ) );
424 return( avl_postapply( root, fn, arg, stopflag ) );
426 fprintf( stderr, "Invalid traversal type %d\n", type );
434 * avl_prefixapply - traverse avl tree root, applying function fprefix
435 * to any nodes that match. fcmp is called with data as its first arg
436 * and the current node's data as its second arg. it should return
437 * 0 if they match, < 0 if data is less, and > 0 if data is greater.
438 * the idea is to efficiently find all nodes that are prefixes of
439 * some key... Like avl_apply, this routine also takes a stopflag
440 * and will return prematurely if fmatch returns this value. Otherwise,
441 * AVL_NOMORE is returned.
458 return( AVL_NOMORE );
460 cmp = (*fcmp)( data, root->avl_data /* , carg */);
462 if ( (*fmatch)( root->avl_data, marg ) == stopflag )
465 if ( root->avl_left != 0 )
466 if ( avl_prefixapply( root->avl_left, data, fmatch,
467 marg, fcmp, carg, stopflag ) == stopflag )
470 if ( root->avl_right != 0 )
471 return( avl_prefixapply( root->avl_right, data, fmatch,
472 marg, fcmp, carg, stopflag ) );
474 return( AVL_NOMORE );
476 } else if ( cmp < 0 ) {
477 if ( root->avl_left != 0 )
478 return( avl_prefixapply( root->avl_left, data, fmatch,
479 marg, fcmp, carg, stopflag ) );
481 if ( root->avl_right != 0 )
482 return( avl_prefixapply( root->avl_right, data, fmatch,
483 marg, fcmp, carg, stopflag ) );
486 return( AVL_NOMORE );
490 * avl_free -- traverse avltree root, freeing the memory it is using.
491 * the dfree() is called to free the data portion of each node. The
492 * number of items actually freed is returned.
496 avl_free( Avlnode *root, AVL_FREE dfree )
504 if ( root->avl_left != 0 )
505 nleft = avl_free( root->avl_left, dfree );
507 if ( root->avl_right != 0 )
508 nright = avl_free( root->avl_right, dfree );
511 (*dfree)( root->avl_data );
514 return( nleft + nright + 1 );
518 * avl_find -- search avltree root for a node with data data. the function
519 * cmp is used to compare things. it is called with data as its first arg
520 * and the current node data as its second. it should return 0 if they match,
521 * < 0 if arg1 is less than arg2 and > 0 if arg1 is greater than arg2.
525 avl_find2( Avlnode *root, const void *data, AVL_CMP fcmp )
529 while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
531 root = root->avl_link[cmp];
537 avl_find( Avlnode *root, const void* data, AVL_CMP fcmp )
541 while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
543 root = root->avl_link[cmp];
546 return( root ? root->avl_data : 0 );
550 * avl_find_lin -- search avltree root linearly for a node with data data.
551 * the function cmp is used to compare things. it is called with data as its
552 * first arg and the current node data as its second. it should return 0 if
553 * they match, non-zero otherwise.
557 avl_find_lin( Avlnode *root, const void* data, AVL_CMP fcmp )
564 if ( (*fcmp)( data, root->avl_data ) == 0 )
565 return( root->avl_data );
567 if ( root->avl_left != 0 )
568 if ( (res = avl_find_lin( root->avl_left, data, fcmp ))
572 if ( root->avl_right == 0 )
575 return( avl_find_lin( root->avl_right, data, fcmp ) );
578 /* NON-REENTRANT INTERFACE */
580 static void* *avl_list;
581 static int avl_maxlist;
582 static int avl_nextlist;
584 #define AVL_GRABSIZE 100
588 avl_buildlist( void* data, void* arg )
592 if ( avl_list == (void* *) 0 ) {
593 avl_list = (void* *) ber_memalloc(AVL_GRABSIZE * sizeof(void*));
594 slots = AVL_GRABSIZE;
596 } else if ( avl_maxlist == slots ) {
597 slots += AVL_GRABSIZE;
598 avl_list = (void* *) ber_memrealloc( (char *) avl_list,
599 (unsigned) slots * sizeof(void*));
602 avl_list[ avl_maxlist++ ] = data;
608 * avl_getfirst() and avl_getnext() are provided as alternate tree
609 * traversal methods, to be used when a single function cannot be
610 * provided to be called with every node in the tree. avl_getfirst()
611 * traverses the tree and builds a linear list of all the nodes,
612 * returning the first node. avl_getnext() returns the next thing
613 * on the list built by avl_getfirst(). This means that avl_getfirst()
614 * can take a while, and that the tree should not be messed with while
615 * being traversed in this way, and that multiple traversals (even of
616 * different trees) cannot be active at once.
620 avl_getfirst( Avlnode *root )
623 ber_memfree( (char *) avl_list);
624 avl_list = (void* *) 0;
632 (void) avl_apply( root, avl_buildlist, (void*) 0, -1, AVL_INORDER );
634 return( avl_list[ avl_nextlist++ ] );
643 if ( avl_nextlist == avl_maxlist ) {
644 ber_memfree( (void*) avl_list);
645 avl_list = (void* *) 0;
649 return( avl_list[ avl_nextlist++ ] );
652 /* end non-reentrant code */
656 avl_dup_error( void* left, void* right )
662 avl_dup_ok( void* left, void* right )