1 /* ========================================================================== **
2 * ubi_BinTree.c
3 *
4 * Copyright (C) 1991-1997 by Christopher R. Hertel
5 *
6 * Email: crh@ubiqx.mn.org
7 * -------------------------------------------------------------------------- **
8 *
9 * This module implements a simple binary tree.
10 *
11 * -------------------------------------------------------------------------- **
12 *
13 * This library is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU Library General Public
15 * License as published by the Free Software Foundation; either
16 * version 2 of the License, or (at your option) any later version.
17 *
18 * This library is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 * Library General Public License for more details.
22 *
23 * You should have received a copy of the GNU Library General Public
24 * License along with this library; if not, write to the Free
25 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 *
27 * -------------------------------------------------------------------------- **
28 *
29 * Log: ubi_BinTree.c,v
30 * Revision 2.5 1997/12/23 03:56:29 crh
31 * In this version, all constants & macros defined in the header file have
32 * the ubi_tr prefix. Also cleaned up anything that gcc complained about
33 * when run with '-pedantic -fsyntax-only -Wall'.
34 *
35 * Revision 2.4 1997/07/26 04:11:10 crh
36 * + Just to be annoying I changed ubi_TRUE and ubi_FALSE to ubi_trTRUE
37 * and ubi_trFALSE.
38 * + There is now a type ubi_trBool to go with ubi_trTRUE and ubi_trFALSE.
39 * + There used to be something called "ubi_TypeDefs.h". I got rid of it.
40 * + Added function ubi_btLeafNode().
41 *
42 * Revision 2.3 1997/06/03 05:16:17 crh
43 * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid conflicts.
44 * Also changed the interface to function InitTree(). See the comments
45 * for this function for more information.
46 *
47 * Revision 2.2 1995/10/03 22:00:07 CRH
48 * Ubisized!
49 *
50 * Revision 2.1 95/03/09 23:37:10 CRH
51 * Added the ModuleID static string and function. These modules are now
52 * self-identifying.
53 *
54 * Revision 2.0 95/02/27 22:00:17 CRH
55 * Revision 2.0 of this program includes the following changes:
56 *
57 * 1) A fix to a major typo in the RepaceNode() function.
58 * 2) The addition of the static function Border().
59 * 3) The addition of the public functions FirstOf() and LastOf(), which
60 * use Border(). These functions are used with trees that allow
61 * duplicate keys.
62 * 4) A complete rewrite of the Locate() function. Locate() now accepts
63 * a "comparison" operator.
64 * 5) Overall enhancements to both code and comments.
65 *
66 * I decided to give this a new major rev number because the interface has
67 * changed. In particular, there are two new functions, and changes to the
68 * Locate() function.
69 *
70 * Revision 1.0 93/10/15 22:44:59 CRH
71 * With this revision, I have added a set of #define's that provide a single,
72 * standard API to all existing tree modules. Until now, each of the three
73 * existing modules had a different function and typedef prefix, as follows:
74 *
75 * Module Prefix
76 * ubi_BinTree ubi_bt
77 * ubi_AVLtree ubi_avl
78 * ubi_SplayTree ubi_spt
79 *
80 * To further complicate matters, only those portions of the base module
81 * (ubi_BinTree) that were superceeded in the new module had the new names.
82 * For example, if you were using ubi_AVLtree, the AVL node structure was
83 * named "ubi_avlNode", but the root structure was still "ubi_btRoot". Using
84 * SplayTree, the locate function was called "ubi_sptLocate", but the next
85 * and previous functions remained "ubi_btNext" and "ubi_btPrev".
86 *
87 * This was not too terrible if you were familiar with the modules and knew
88 * exactly which tree model you wanted to use. If you wanted to be able to
89 * change modules (for speed comparisons, etc), things could get messy very
90 * quickly.
91 *
92 * So, I have added a set of defined names that get redefined in any of the
93 * descendant modules. To use this standardized interface in your code,
94 * simply replace all occurances of "ubi_bt", "ubi_avl", and "ubi_spt" with
95 * "ubi_tr". The "ubi_tr" names will resolve to the correct function or
96 * datatype names for the module that you are using. Just remember to
97 * include the header for that module in your program file. Because these
98 * names are handled by the preprocessor, there is no added run-time
99 * overhead.
100 *
101 * Note that the original names do still exist, and can be used if you wish
102 * to write code directly to a specific module. This should probably only be
103 * done if you are planning to implement a new descendant type, such as
104 * red/black trees. CRH
105 *
106 * V0.0 - June, 1991 - Written by Christopher R. Hertel (CRH).
107 *
108 * ========================================================================== **
109 */
110
111 #include "ubi_BinTree.h" /* Header for this module */
112 #include <stdlib.h> /* Standard C definitions. */
113
114 /* ========================================================================== **
115 * Static data.
116 */
117
118 static char ModuleID[] = "ubi_BinTree\n\
119 \tRevision: 2.5\n\
120 \tDate: 1997/12/23 03:56:29\n\
121 \tAuthor: crh\n";
122
123 /* ========================================================================== **
124 * Internal (private) functions.
125 */
126
qFind(ubi_btCompFunc cmp,ubi_btItemPtr FindMe,register ubi_btNodePtr p)127 static ubi_btNodePtr qFind( ubi_btCompFunc cmp,
128 ubi_btItemPtr FindMe,
129 register ubi_btNodePtr p )
130 /* ------------------------------------------------------------------------ **
131 * This function performs a non-recursive search of a tree for a node
132 * matching a specific key. It is called "qFind()" because it is
133 * faster that TreeFind (below).
134 *
135 * Input:
136 * cmp - a pointer to the tree's comparison function.
137 * FindMe - a pointer to the key value for which to search.
138 * p - a pointer to the starting point of the search. <p>
139 * is considered to be the root of a subtree, and only
140 * the subtree will be searched.
141 *
142 * Output:
143 * A pointer to a node with a key that matches the key indicated by
144 * FindMe, or NULL if no such node was found.
145 *
146 * Note: In a tree that allows duplicates, the pointer returned *might
147 * not* point to the (sequentially) first occurance of the
148 * desired key.
149 * ------------------------------------------------------------------------ **
150 */
151 {
152 int tmp;
153
154 while( p && (( tmp = ubi_trAbNormal((*cmp)(FindMe, p)) ) != ubi_trEQUAL) )
155 p = p->Link[tmp];
156
157 return( p );
158 } /* qFind */
159
TreeFind(ubi_btItemPtr findme,ubi_btNodePtr p,ubi_btNodePtr * parentp,char * gender,ubi_btCompFunc CmpFunc)160 static ubi_btNodePtr TreeFind( ubi_btItemPtr findme,
161 ubi_btNodePtr p,
162 ubi_btNodePtr *parentp,
163 char *gender,
164 ubi_btCompFunc CmpFunc )
165 /* ------------------------------------------------------------------------ **
166 * TreeFind() searches a tree for a given value (findme). It will return a
167 * pointer to the target node, if found, or NULL if the target node was not
168 * found.
169 *
170 * TreeFind() also returns, via parameters, a pointer to the parent of the
171 * target node, and a LEFT or RIGHT value indicating which child of the
172 * parent is the target node. *If the target is not found*, then these
173 * values indicate the place at which the target *should be found*. This
174 * is useful when inserting a new node into a tree or searching for nodes
175 * "near" the target node.
176 *
177 * The parameters are:
178 *
179 * findme - is a pointer to the key information to be searched for.
180 * p - points to the root of the tree to be searched.
181 * parentp - will return a pointer to a pointer to the !parent! of the
182 * target node, which can be especially usefull if the target
183 * was not found.
184 * gender - returns LEFT or RIGHT to indicate which child of *parentp
185 * was last searched.
186 * CmpFunc - points to the comparison function.
187 *
188 * This function is called by ubi_btLocate() and ubi_btInsert().
189 * ------------------------------------------------------------------------ **
190 */
191 {
192 register ubi_btNodePtr tmp_p = p;
193 ubi_btNodePtr tmp_pp = NULL;
194 int tmp_gender = ubi_trEQUAL;
195 int tmp_cmp;
196
197 while( tmp_p
198 && (ubi_trEQUAL != (tmp_cmp = ubi_trAbNormal((*CmpFunc)(findme, tmp_p)))) )
199 {
200 tmp_pp = tmp_p; /* Keep track of previous node. */
201 tmp_gender = tmp_cmp; /* Keep track of sex of child. */
202 tmp_p = tmp_p->Link[tmp_cmp]; /* Go to child. */
203 }
204 *parentp = tmp_pp; /* Return results. */
205 *gender = tmp_gender;
206 return( tmp_p );
207 } /* TreeFind */
208
ReplaceNode(ubi_btNodePtr * parent,ubi_btNodePtr oldnode,ubi_btNodePtr newnode)209 static void ReplaceNode( ubi_btNodePtr *parent,
210 ubi_btNodePtr oldnode,
211 ubi_btNodePtr newnode )
212 /* ------------------------------------------------------------------ *
213 * Remove node oldnode from the tree, replacing it with node newnode.
214 *
215 * Input:
216 * parent - A pointer to he parent pointer of the node to be
217 * replaced. <parent> may point to the Link[] field of
218 * a parent node, or it may indicate the root pointer at
219 * the top of the tree.
220 * oldnode - A pointer to the node that is to be replaced.
221 * newnode - A pointer to the node that is to be installed in the
222 * place of <*oldnode>.
223 *
224 * Notes: Don't forget to free oldnode.
225 * Also, this function used to have a really nasty typo
226 * bug. "oldnode" and "newnode" were swapped in the line
227 * that now reads:
228 * ((unsigned char *)newnode)[i] = ((unsigned char *)oldnode)[i];
229 * Bleah!
230 * ------------------------------------------------------------------ *
231 */
232 {
233 register int i;
234 register int btNodeSize = sizeof( ubi_btNode );
235
236 for( i = 0; i < btNodeSize; i++ ) /* Copy node internals to new node. */
237 ((unsigned char *)newnode)[i] = ((unsigned char *)oldnode)[i];
238 (*parent) = newnode; /* Old node's parent points to new child. */
239 /* Now tell the children about their new step-parent. */
240 if( oldnode->Link[ubi_trLEFT] )
241 (oldnode->Link[ubi_trLEFT])->Link[ubi_trPARENT] = newnode;
242 if( oldnode->Link[ubi_trRIGHT] )
243 (oldnode->Link[ubi_trRIGHT])->Link[ubi_trPARENT] = newnode;
244 } /* ReplaceNode */
245
SwapNodes(ubi_btRootPtr RootPtr,ubi_btNodePtr Node1,ubi_btNodePtr Node2)246 static void SwapNodes( ubi_btRootPtr RootPtr,
247 ubi_btNodePtr Node1,
248 ubi_btNodePtr Node2 )
249 /* ------------------------------------------------------------------------ **
250 * This function swaps two nodes in the tree. Node1 will take the place of
251 * Node2, and Node2 will fill in the space left vacant by Node 1.
252 *
253 * Input:
254 * RootPtr - pointer to the tree header structure for this tree.
255 * Node1 - \
256 * > These are the two nodes which are to be swapped.
257 * Node2 - /
258 *
259 * Notes:
260 * This function does a three step swap, using a dummy node as a place
261 * holder. This function is used by ubi_btRemove().
262 * ------------------------------------------------------------------------ **
263 */
264 {
265 ubi_btNodePtr *Parent;
266 ubi_btNode dummy;
267 ubi_btNodePtr dummy_p = &dummy;
268
269 /* Replace Node 1 with the dummy, thus removing Node1 from the tree. */
270 if( Node1->Link[ubi_trPARENT] )
271 Parent = &((Node1->Link[ubi_trPARENT])->Link[(int)(Node1->gender)]);
272 else
273 Parent = &(RootPtr->root);
274 ReplaceNode( Parent, Node1, dummy_p );
275
276 /* Swap Node 1 with Node 2, placing Node 1 back into the tree. */
277 if( Node2->Link[ubi_trPARENT] )
278 Parent = &((Node2->Link[ubi_trPARENT])->Link[(int)(Node2->gender)]);
279 else
280 Parent = &(RootPtr->root);
281 ReplaceNode( Parent, Node2, Node1 );
282
283 /* Swap Node 2 and the dummy, thus placing Node 2 back into the tree. */
284 if( dummy_p->Link[ubi_trPARENT] )
285 Parent = &((dummy_p->Link[ubi_trPARENT])->Link[(int)(dummy_p->gender)]);
286 else
287 Parent = &(RootPtr->root);
288 ReplaceNode( Parent, dummy_p, Node2 );
289 } /* SwapNodes */
290
291 /* -------------------------------------------------------------------------- **
292 * These routines allow you to walk through the tree, forwards or backwards.
293 */
294
SubSlide(register ubi_btNodePtr P,register int whichway)295 static ubi_btNodePtr SubSlide( register ubi_btNodePtr P,
296 register int whichway )
297 /* ------------------------------------------------------------------------ **
298 * Slide down the side of a subtree.
299 *
300 * Given a starting node, this function returns a pointer to the LEFT-, or
301 * RIGHT-most descendent, *or* (if whichway is PARENT) to the tree root.
302 *
303 * Input: P - a pointer to a starting place.
304 * whichway - the direction (LEFT, RIGHT, or PARENT) in which to
305 * travel.
306 * Output: A pointer to a node that is either the root, or has no
307 * whichway-th child but is within the subtree of P. Note that
308 * the return value may be the same as P. The return value *will
309 * be* NULL if P is NULL.
310 * ------------------------------------------------------------------------ **
311 */
312 {
313 ubi_btNodePtr Q = NULL;
314
315 while( P )
316 {
317 Q = P;
318 P = P->Link[ whichway ];
319 }
320 return( Q );
321 } /* SubSlide */
322
Neighbor(register ubi_btNodePtr P,register int whichway)323 static ubi_btNodePtr Neighbor( register ubi_btNodePtr P,
324 register int whichway )
325 /* ------------------------------------------------------------------------ **
326 * Given starting point p, return the (key order) next or preceeding node
327 * in the tree.
328 *
329 * Input: P - Pointer to our starting place node.
330 * whichway - the direction in which to travel to find the
331 * neighbor, i.e., the RIGHT neighbor or the LEFT
332 * neighbor.
333 *
334 * Output: A pointer to the neighboring node, or NULL if P was NULL.
335 *
336 * Notes: If whichway is PARENT, the results are unpredictable.
337 * ------------------------------------------------------------------------ **
338 */
339 {
340 if( P )
341 {
342 if( P->Link[ whichway ] )
343 return( SubSlide( P->Link[ whichway ], (char)ubi_trRevWay(whichway) ) );
344 else
345 while( P->Link[ ubi_trPARENT ] )
346 {
347 if( (P->Link[ ubi_trPARENT ])->Link[ whichway ] == P )
348 P = P->Link[ ubi_trPARENT ];
349 else
350 return( P->Link[ ubi_trPARENT ] );
351 }
352 }
353 return( NULL );
354 } /* Neighbor */
355
Border(ubi_btRootPtr RootPtr,ubi_btItemPtr FindMe,ubi_btNodePtr p,int whichway)356 static ubi_btNodePtr Border( ubi_btRootPtr RootPtr,
357 ubi_btItemPtr FindMe,
358 ubi_btNodePtr p,
359 int whichway )
360 /* ------------------------------------------------------------------------ **
361 * Given starting point p, which has a key value equal to *FindMe, locate
362 * the first (index order) node with the same key value.
363 *
364 * This function is useful in trees that have can have duplicate keys.
365 * For example, consider the following tree:
366 * Tree Traversal
367 * 2 If <p> points to the root and <whichway> is RIGHT, 3
368 * / \ then the return value will be a pointer to the / \
369 * 2 2 RIGHT child of the root node. The tree on 2 5
370 * / / \ the right shows the order of traversal. / / \
371 * 1 2 3 1 4 6
372 *
373 * Input: RootPtr - Pointer to the tree root structure.
374 * FindMe - Key value for comparisons.
375 * p - Pointer to the starting-point node.
376 * whichway - the direction in which to travel to find the
377 * neighbor, i.e., the RIGHT neighbor or the LEFT
378 * neighbor.
379 *
380 * Output: A pointer to the first (index, or "traversal", order) node with
381 * a Key value that matches *FindMe.
382 *
383 * Notes: If whichway is PARENT, or if the tree does not allow duplicate
384 * keys, this function will return <p>.
385 * ------------------------------------------------------------------------ **
386 */
387 {
388 register ubi_btNodePtr q;
389
390 /* Exit if there's nothing that can be done. */
391 if( !ubi_trDups_OK( RootPtr ) || (ubi_trPARENT == whichway) )
392 return( p );
393
394 /* First, if needed, move up the tree. We need to get to the root of the
395 * subtree that contains all of the matching nodes.
396 */
397 q = p->Link[ubi_trPARENT];
398 while( q && (ubi_trEQUAL == ubi_trAbNormal( (*(RootPtr->cmp))(FindMe, q) )) )
399 {
400 p = q;
401 q = p->Link[ubi_trPARENT];
402 }
403
404 /* Next, move back down in the "whichway" direction. */
405 q = p->Link[whichway];
406 while( q )
407 {
408 q = qFind( RootPtr->cmp, FindMe, q );
409 if( q )
410 {
411 p = q;
412 q = p->Link[whichway];
413 }
414 }
415 return( p );
416 } /* Border */
417
418
419 /* ========================================================================== **
420 * Exported utilities.
421 */
422
ubi_btSgn(register long x)423 long ubi_btSgn( register long x )
424 /* ------------------------------------------------------------------------ **
425 * Return the sign of x; {negative,zero,positive} ==> {-1, 0, 1}.
426 *
427 * Input: x - a signed long integer value.
428 *
429 * Output: the "sign" of x, represented as follows:
430 * -1 == negative
431 * 0 == zero (no sign)
432 * 1 == positive
433 *
434 * Note: This utility is provided in order to facilitate the conversion
435 * of C comparison function return values into BinTree direction
436 * values: {LEFT, PARENT, EQUAL}. It is INCORPORATED into the
437 * ubi_trAbNormal() conversion macro!
438 *
439 * ------------------------------------------------------------------------ **
440 */
441 {
442 return( (x)?((x>0)?(1):(-1)):(0) );
443 } /* ubi_btSgn */
444
ubi_btInitNode(ubi_btNodePtr NodePtr)445 ubi_btNodePtr ubi_btInitNode( ubi_btNodePtr NodePtr )
446 /* ------------------------------------------------------------------------ **
447 * Initialize a tree node.
448 *
449 * Input: a pointer to a ubi_btNode structure to be initialized.
450 * Output: a pointer to the initialized ubi_btNode structure (ie. the
451 * same as the input pointer).
452 * ------------------------------------------------------------------------ **
453 */
454 {
455 NodePtr->Link[ ubi_trLEFT ] = NULL;
456 NodePtr->Link[ ubi_trPARENT ] = NULL;
457 NodePtr->Link[ ubi_trRIGHT ] = NULL;
458 NodePtr->gender = ubi_trEQUAL;
459 return( NodePtr );
460 } /* ubi_btInitNode */
461
ubi_btInitTree(ubi_btRootPtr RootPtr,ubi_btCompFunc CompFunc,unsigned char Flags)462 ubi_btRootPtr ubi_btInitTree( ubi_btRootPtr RootPtr,
463 ubi_btCompFunc CompFunc,
464 unsigned char Flags )
465 /* ------------------------------------------------------------------------ **
466 * Initialize the fields of a Tree Root header structure.
467 *
468 * Input: RootPtr - a pointer to an ubi_btRoot structure to be
469 * initialized.
470 * CompFunc - a pointer to a comparison function that will be used
471 * whenever nodes in the tree must be compared against
472 * outside values.
473 * Flags - One bytes worth of flags. Flags include
474 * ubi_trOVERWRITE and ubi_trDUPKEY. See the header
475 * file for more info.
476 *
477 * Output: a pointer to the initialized ubi_btRoot structure (ie. the
478 * same value as RootPtr).
479 *
480 * Note: The interface to this function has changed from that of
481 * previous versions. The <Flags> parameter replaces two
482 * boolean parameters that had the same basic effect.
483 *
484 * ------------------------------------------------------------------------ **
485 */
486 {
487 if( RootPtr )
488 {
489 RootPtr->root = NULL;
490 RootPtr->count = 0L;
491 RootPtr->cmp = CompFunc;
492 RootPtr->flags = (Flags & ubi_trDUPKEY) ? ubi_trDUPKEY : Flags;
493 } /* There are only two supported flags, and they are
494 * mutually exclusive. ubi_trDUPKEY takes precedence
495 * over ubi_trOVERWRITE.
496 */
497 return( RootPtr );
498 } /* ubi_btInitTree */
499
ubi_btInsert(ubi_btRootPtr RootPtr,ubi_btNodePtr NewNode,ubi_btItemPtr ItemPtr,ubi_btNodePtr * OldNode)500 ubi_trBool ubi_btInsert( ubi_btRootPtr RootPtr,
501 ubi_btNodePtr NewNode,
502 ubi_btItemPtr ItemPtr,
503 ubi_btNodePtr *OldNode )
504 /* ------------------------------------------------------------------------ **
505 * This function uses a non-recursive algorithm to add a new element to the
506 * tree.
507 *
508 * Input: RootPtr - a pointer to the ubi_btRoot structure that indicates
509 * the root of the tree to which NewNode is to be added.
510 * NewNode - a pointer to an ubi_btNode structure that is NOT
511 * part of any tree.
512 * ItemPtr - A pointer to the sort key that is stored within
513 * *NewNode. ItemPtr MUST point to information stored
514 * in *NewNode or an EXACT DUPLICATE. The key data
515 * indicated by ItemPtr is used to place the new node
516 * into the tree.
517 * OldNode - a pointer to an ubi_btNodePtr. When searching
518 * the tree, a duplicate node may be found. If
519 * duplicates are allowed, then the new node will
520 * be simply placed into the tree. If duplicates
521 * are not allowed, however, then one of two things
522 * may happen.
523 * 1) if overwritting *is not* allowed, this
524 * function will return FALSE (indicating that
525 * the new node could not be inserted), and
526 * *OldNode will point to the duplicate that is
527 * still in the tree.
528 * 2) if overwritting *is* allowed, then this
529 * function will swap **OldNode for *NewNode.
530 * In this case, *OldNode will point to the node
531 * that was removed (thus allowing you to free
532 * the node).
533 * ** If you are using overwrite mode, ALWAYS **
534 * ** check the return value of this parameter! **
535 * Note: You may pass NULL in this parameter, the
536 * function knows how to cope. If you do this,
537 * however, there will be no way to return a
538 * pointer to an old (ie. replaced) node (which is
539 * a problem if you are using overwrite mode).
540 *
541 * Output: a boolean value indicating success or failure. The function
542 * will return FALSE if the node could not be added to the tree.
543 * Such failure will only occur if duplicates are not allowed,
544 * nodes cannot be overwritten, AND a duplicate key was found
545 * within the tree.
546 * ------------------------------------------------------------------------ **
547 */
548 {
549 ubi_btNodePtr OtherP,
550 parent = NULL;
551 char tmp;
552
553 if( !(OldNode) ) /* If they didn't give us a pointer, supply our own. */
554 OldNode = &OtherP;
555
556 (void)ubi_btInitNode( NewNode ); /* Init the new node's BinTree fields. */
557
558 /* Find a place for the new node. */
559 *OldNode = TreeFind(ItemPtr, (RootPtr->root), &parent, &tmp, (RootPtr->cmp));
560
561 /* Now add the node to the tree... */
562 if (!(*OldNode)) /* The easy one: we have a space for a new node! */
563 {
564 if (!(parent))
565 RootPtr->root = NewNode;
566 else
567 {
568 parent->Link[(int)tmp] = NewNode;
569 NewNode->Link[ubi_trPARENT] = parent;
570 NewNode->gender = tmp;
571 }
572 (RootPtr->count)++;
573 return( ubi_trTRUE );
574 }
575
576 /* If we reach this point, we know that a duplicate node exists. This
577 * section adds the node to the tree if duplicate keys are allowed.
578 */
579 if( ubi_trDups_OK(RootPtr) ) /* Key exists, add duplicate */
580 {
581 ubi_btNodePtr q;
582
583 tmp = ubi_trRIGHT;
584 q = (*OldNode);
585 *OldNode = NULL;
586 while( q )
587 {
588 parent = q;
589 if( tmp == ubi_trEQUAL )
590 tmp = ubi_trRIGHT;
591 q = q->Link[(int)tmp];
592 if ( q )
593 tmp = ubi_trAbNormal( (*(RootPtr->cmp))(ItemPtr, q) );
594 }
595 parent->Link[(int)tmp] = NewNode;
596 NewNode->Link[ubi_trPARENT] = parent;
597 NewNode->gender = tmp;
598 (RootPtr->count)++;
599 return( ubi_trTRUE );
600 }
601
602 /* If we get to *this* point, we know that we are not allowed to have
603 * duplicate nodes, but our node keys match, so... may we replace the
604 * old one?
605 */
606 if( ubi_trOvwt_OK(RootPtr) ) /* Key exists, we replace */
607 {
608 if (!(parent))
609 ReplaceNode( &(RootPtr->root), *OldNode, NewNode );
610 else
611 ReplaceNode( &(parent->Link[(int)((*OldNode)->gender)]),
612 *OldNode, NewNode );
613 return( ubi_trTRUE );
614 }
615
616 return( ubi_trFALSE ); /* Failure: could not replace an existing node. */
617 } /* ubi_btInsert */
618
ubi_btRemove(ubi_btRootPtr RootPtr,ubi_btNodePtr DeadNode)619 ubi_btNodePtr ubi_btRemove( ubi_btRootPtr RootPtr,
620 ubi_btNodePtr DeadNode )
621 /* ------------------------------------------------------------------------ **
622 * This function removes the indicated node from the tree.
623 *
624 * Input: RootPtr - A pointer to the header of the tree that contains
625 * the node to be removed.
626 * DeadNode - A pointer to the node that will be removed.
627 *
628 * Output: This function returns a pointer to the node that was removed
629 * from the tree (ie. the same as DeadNode).
630 *
631 * Note: The node MUST be in the tree indicated by RootPtr. If not,
632 * strange and evil things will happen to your trees.
633 * ------------------------------------------------------------------------ **
634 */
635 {
636 ubi_btNodePtr p,
637 *parentp;
638 int tmp;
639
640 /* if the node has both left and right subtrees, then we have to swap
641 * it with another node. The other node we choose will be the Prev()ious
642 * node, which is garunteed to have no RIGHT child.
643 */
644 if( (DeadNode->Link[ubi_trLEFT]) && (DeadNode->Link[ubi_trRIGHT]) )
645 SwapNodes( RootPtr, DeadNode, ubi_btPrev( DeadNode ) );
646
647 /* The parent of the node to be deleted may be another node, or it may be
648 * the root of the tree. Since we're not sure, it's best just to have
649 * a pointer to the parent pointer, whatever it is.
650 */
651 if (DeadNode->Link[ubi_trPARENT])
652 parentp = &((DeadNode->Link[ubi_trPARENT])->Link[(int)(DeadNode->gender)]);
653 else
654 parentp = &( RootPtr->root );
655
656 /* Now link the parent to the only grand-child and patch up the gender. */
657 tmp = ((DeadNode->Link[ubi_trLEFT])?ubi_trLEFT:ubi_trRIGHT);
658
659 p = (DeadNode->Link[tmp]);
660 if( p )
661 {
662 p->Link[ubi_trPARENT] = DeadNode->Link[ubi_trPARENT];
663 p->gender = DeadNode->gender;
664 }
665 (*parentp) = p;
666
667 /* Finished, reduce the node count and return. */
668 (RootPtr->count)--;
669 return( DeadNode );
670 } /* ubi_btRemove */
671
ubi_btLocate(ubi_btRootPtr RootPtr,ubi_btItemPtr FindMe,ubi_trCompOps CompOp)672 ubi_btNodePtr ubi_btLocate( ubi_btRootPtr RootPtr,
673 ubi_btItemPtr FindMe,
674 ubi_trCompOps CompOp )
675 /* ------------------------------------------------------------------------ **
676 * The purpose of ubi_btLocate() is to find a node or set of nodes given
677 * a target value and a "comparison operator". The Locate() function is
678 * more flexible and (in the case of trees that may contain dupicate keys)
679 * more precise than the ubi_btFind() function. The latter is faster,
680 * but it only searches for exact matches and, if the tree contains
681 * duplicates, Find() may return a pointer to any one of the duplicate-
682 * keyed records.
683 *
684 * Input:
685 * RootPtr - A pointer to the header of the tree to be searched.
686 * FindMe - An ubi_btItemPtr that indicates the key for which to
687 * search.
688 * CompOp - One of the following:
689 * CompOp Return a pointer to the node with
690 * ------ ---------------------------------
691 * ubi_trLT - the last key value that is less
692 * than FindMe.
693 * ubi_trLE - the first key matching FindMe, or
694 * the last key that is less than
695 * FindMe.
696 * ubi_trEQ - the first key matching FindMe.
697 * ubi_trGE - the first key matching FindMe, or the
698 * first key greater than FindMe.
699 * ubi_trGT - the first key greater than FindMe.
700 * Output:
701 * A pointer to the node matching the criteria listed above under
702 * CompOp, or NULL if no node matched the criteria.
703 *
704 * Notes:
705 * In the case of trees with duplicate keys, Locate() will behave as
706 * follows:
707 *
708 * Find: 3 Find: 3
709 * Keys: 1 2 2 2 3 3 3 3 3 4 4 Keys: 1 1 2 2 2 4 4 5 5 5 6
710 * ^ ^ ^ ^ ^
711 * LT EQ GT LE GE
712 *
713 * That is, when returning a pointer to a node with a key that is LESS
714 * THAN the target key (FindMe), Locate() will return a pointer to the
715 * LAST matching node.
716 * When returning a pointer to a node with a key that is GREATER
717 * THAN the target key (FindMe), Locate() will return a pointer to the
718 * FIRST matching node.
719 *
720 * See Also: ubi_btFind(), ubi_btFirstOf(), ubi_btLastOf().
721 * ------------------------------------------------------------------------ **
722 */
723 {
724 register ubi_btNodePtr p;
725 ubi_btNodePtr parent;
726 char whichkid;
727
728 /* Start by searching for a matching node. */
729 p = TreeFind( FindMe,
730 RootPtr->root,
731 &parent,
732 &whichkid,
733 RootPtr->cmp );
734
735 if( p ) /* If we have found a match, we can resolve as follows: */
736 {
737 switch( CompOp )
738 {
739 case ubi_trLT: /* It's just a jump to the left... */
740 p = Border( RootPtr, FindMe, p, ubi_trLEFT );
741 return( Neighbor( p, ubi_trLEFT ) );
742 case ubi_trGT: /* ...and then a jump to the right. */
743 p = Border( RootPtr, FindMe, p, ubi_trRIGHT );
744 return( Neighbor( p, ubi_trRIGHT ) );
745 default:
746 p = Border( RootPtr, FindMe, p, ubi_trLEFT );
747 return( p );
748 }
749 }
750
751 /* Else, no match. */
752 if( ubi_trEQ == CompOp ) /* If we were looking for an exact match... */
753 return( NULL ); /* ...forget it. */
754
755 /* We can still return a valid result for GT, GE, LE, and LT.
756 * <parent> points to a node with a value that is either just before or
757 * just after the target value.
758 * Remaining possibilities are LT and GT (including LE & GE).
759 */
760 if( (ubi_trLT == CompOp) || (ubi_trLE == CompOp) )
761 return( (ubi_trLEFT == whichkid) ? Neighbor( parent, whichkid ) : parent );
762 else
763 return( (ubi_trRIGHT == whichkid) ? Neighbor( parent, whichkid ) : parent );
764 } /* ubi_btLocate */
765
ubi_btFind(ubi_btRootPtr RootPtr,ubi_btItemPtr FindMe)766 ubi_btNodePtr ubi_btFind( ubi_btRootPtr RootPtr,
767 ubi_btItemPtr FindMe )
768 /* ------------------------------------------------------------------------ **
769 * This function performs a non-recursive search of a tree for any node
770 * matching a specific key.
771 *
772 * Input:
773 * RootPtr - a pointer to the header of the tree to be searched.
774 * FindMe - a pointer to the key value for which to search.
775 *
776 * Output:
777 * A pointer to a node with a key that matches the key indicated by
778 * FindMe, or NULL if no such node was found.
779 *
780 * Note: In a tree that allows duplicates, the pointer returned *might
781 * not* point to the (sequentially) first occurance of the
782 * desired key. In such a tree, it may be more useful to use
783 * ubi_btLocate().
784 * ------------------------------------------------------------------------ **
785 */
786 {
787 return( qFind( RootPtr->cmp, FindMe, RootPtr->root ) );
788 } /* ubi_btFind */
789
ubi_btNext(ubi_btNodePtr P)790 ubi_btNodePtr ubi_btNext( ubi_btNodePtr P )
791 /* ------------------------------------------------------------------------ **
792 * Given the node indicated by P, find the (sorted order) Next node in the
793 * tree.
794 * Input: P - a pointer to a node that exists in a binary tree.
795 * Output: A pointer to the "next" node in the tree, or NULL if P pointed
796 * to the "last" node in the tree or was NULL.
797 * ------------------------------------------------------------------------ **
798 */
799 {
800 return( Neighbor( P, ubi_trRIGHT ) );
801 } /* ubi_btNext */
802
ubi_btPrev(ubi_btNodePtr P)803 ubi_btNodePtr ubi_btPrev( ubi_btNodePtr P )
804 /* ------------------------------------------------------------------------ **
805 * Given the node indicated by P, find the (sorted order) Previous node in
806 * the tree.
807 * Input: P - a pointer to a node that exists in a binary tree.
808 * Output: A pointer to the "previous" node in the tree, or NULL if P
809 * pointed to the "first" node in the tree or was NULL.
810 * ------------------------------------------------------------------------ **
811 */
812 {
813 return( Neighbor( P, ubi_trLEFT ) );
814 } /* ubi_btPrev */
815
ubi_btFirst(ubi_btNodePtr P)816 ubi_btNodePtr ubi_btFirst( ubi_btNodePtr P )
817 /* ------------------------------------------------------------------------ **
818 * Given the node indicated by P, find the (sorted order) First node in the
819 * subtree of which *P is the root.
820 * Input: P - a pointer to a node that exists in a binary tree.
821 * Output: A pointer to the "first" node in a subtree that has *P as its
822 * root. This function will return NULL only if P is NULL.
823 * Note: In general, you will be passing in the value of the root field
824 * of an ubi_btRoot structure.
825 * ------------------------------------------------------------------------ **
826 */
827 {
828 return( SubSlide( P, ubi_trLEFT ) );
829 } /* ubi_btFirst */
830
ubi_btLast(ubi_btNodePtr P)831 ubi_btNodePtr ubi_btLast( ubi_btNodePtr P )
832 /* ------------------------------------------------------------------------ **
833 * Given the node indicated by P, find the (sorted order) Last node in the
834 * subtree of which *P is the root.
835 * Input: P - a pointer to a node that exists in a binary tree.
836 * Output: A pointer to the "last" node in a subtree that has *P as its
837 * root. This function will return NULL only if P is NULL.
838 * Note: In general, you will be passing in the value of the root field
839 * of an ubi_btRoot structure.
840 * ------------------------------------------------------------------------ **
841 */
842 {
843 return( SubSlide( P, ubi_trRIGHT ) );
844 } /* ubi_btLast */
845
ubi_btFirstOf(ubi_btRootPtr RootPtr,ubi_btItemPtr MatchMe,ubi_btNodePtr p)846 ubi_btNodePtr ubi_btFirstOf( ubi_btRootPtr RootPtr,
847 ubi_btItemPtr MatchMe,
848 ubi_btNodePtr p )
849 /* ------------------------------------------------------------------------ **
850 * Given a tree that a allows duplicate keys, and a pointer to a node in
851 * the tree, this function will return a pointer to the first (traversal
852 * order) node with the same key value.
853 *
854 * Input: RootPtr - A pointer to the root of the tree.
855 * MatchMe - A pointer to the key value. This should probably
856 * point to the key within node *p.
857 * p - A pointer to a node in the tree.
858 * Output: A pointer to the first node in the set of nodes with keys
859 * matching <FindMe>.
860 * Notes: Node *p MUST be in the set of nodes with keys matching
861 * <FindMe>. If not, this function will return NULL.
862 * ------------------------------------------------------------------------ **
863 */
864 {
865 /* If our starting point is invalid, return NULL. */
866 if( !p || ubi_trAbNormal( (*(RootPtr->cmp))( MatchMe, p ) != ubi_trEQUAL ) )
867 return( NULL );
868 return( Border( RootPtr, MatchMe, p, ubi_trLEFT ) );
869 } /* ubi_btFirstOf */
870
ubi_btLastOf(ubi_btRootPtr RootPtr,ubi_btItemPtr MatchMe,ubi_btNodePtr p)871 ubi_btNodePtr ubi_btLastOf( ubi_btRootPtr RootPtr,
872 ubi_btItemPtr MatchMe,
873 ubi_btNodePtr p )
874 /* ------------------------------------------------------------------------ **
875 * Given a tree that a allows duplicate keys, and a pointer to a node in
876 * the tree, this function will return a pointer to the last (traversal
877 * order) node with the same key value.
878 *
879 * Input: RootPtr - A pointer to the root of the tree.
880 * MatchMe - A pointer to the key value. This should probably
881 * point to the key within node *p.
882 * p - A pointer to a node in the tree.
883 * Output: A pointer to the last node in the set of nodes with keys
884 * matching <FindMe>.
885 * Notes: Node *p MUST be in the set of nodes with keys matching
886 * <FindMe>. If not, this function will return NULL.
887 * ------------------------------------------------------------------------ **
888 */
889 {
890 /* If our starting point is invalid, return NULL. */
891 if( !p || ubi_trAbNormal( (*(RootPtr->cmp))( MatchMe, p ) != ubi_trEQUAL ) )
892 return( NULL );
893 return( Border( RootPtr, MatchMe, p, ubi_trRIGHT ) );
894 } /* ubi_btLastOf */
895
ubi_btTraverse(ubi_btRootPtr RootPtr,ubi_btActionRtn EachNode,void * UserData)896 ubi_trBool ubi_btTraverse( ubi_btRootPtr RootPtr,
897 ubi_btActionRtn EachNode,
898 void *UserData )
899 /* ------------------------------------------------------------------------ **
900 * Traverse a tree in sorted order (non-recursively). At each node, call
901 * (*EachNode)(), passing a pointer to the current node, and UserData as the
902 * second parameter.
903 * Input: RootPtr - a pointer to an ubi_btRoot structure that indicates
904 * the tree to be traversed.
905 * EachNode - a pointer to a function to be called at each node
906 * as the node is visited.
907 * UserData - a generic pointer that may point to anything that
908 * you choose.
909 * Output: A boolean value. FALSE if the tree is empty, otherwise TRUE.
910 * ------------------------------------------------------------------------ **
911 */
912 {
913 ubi_btNodePtr p;
914
915 if( !(p = ubi_btFirst( RootPtr->root )) ) return( ubi_trFALSE );
916
917 while( p )
918 {
919 EachNode( p, UserData );
920 p = ubi_btNext( p );
921 }
922 return( ubi_trTRUE );
923 } /* ubi_btTraverse */
924
ubi_btKillTree(ubi_btRootPtr RootPtr,ubi_btKillNodeRtn FreeNode)925 ubi_trBool ubi_btKillTree( ubi_btRootPtr RootPtr,
926 ubi_btKillNodeRtn FreeNode )
927 /* ------------------------------------------------------------------------ **
928 * Delete an entire tree (non-recursively) and reinitialize the ubi_btRoot
929 * structure. Note that this function will return FALSE if either parameter
930 * is NULL.
931 *
932 * Input: RootPtr - a pointer to an ubi_btRoot structure that indicates
933 * the root of the tree to delete.
934 * FreeNode - a function that will be called for each node in the
935 * tree to deallocate the memory used by the node.
936 *
937 * Output: A boolean value. FALSE if either input parameter was NULL, else
938 * TRUE.
939 *
940 * ------------------------------------------------------------------------ **
941 */
942 {
943 ubi_btNodePtr p, q;
944
945 if( !(RootPtr) || !(FreeNode) )
946 return( ubi_trFALSE );
947
948 p = ubi_btFirst( RootPtr->root );
949 while( p )
950 {
951 q = p;
952 while( q->Link[ubi_trRIGHT] )
953 q = SubSlide( q->Link[ubi_trRIGHT], ubi_trLEFT );
954 p = q->Link[ubi_trPARENT];
955 if( p )
956 p->Link[ ((p->Link[ubi_trLEFT] == q)?ubi_trLEFT:ubi_trRIGHT) ] = NULL;
957 FreeNode((void *)q);
958 }
959
960 (void)ubi_btInitTree( RootPtr,
961 RootPtr->cmp,
962 RootPtr->flags );
963 return( ubi_trTRUE );
964 } /* ubi_btKillTree */
965
ubi_btLeafNode(ubi_btNodePtr leader)966 ubi_btNodePtr ubi_btLeafNode( ubi_btNodePtr leader )
967 /* ------------------------------------------------------------------------ **
968 * Returns a pointer to a leaf node.
969 *
970 * Input: leader - Pointer to a node at which to start the descent.
971 *
972 * Output: A pointer to a leaf node selected in a somewhat arbitrary
973 * manner.
974 *
975 * Notes: I wrote this function because I was using splay trees as a
976 * database cache. The cache had a maximum size on it, and I
977 * needed a way of choosing a node to sacrifice if the cache
978 * became full. In a splay tree, less recently accessed nodes
979 * tend toward the bottom of the tree, meaning that leaf nodes
980 * are good candidates for removal. (I really can't think of
981 * any other reason to use this function.)
982 * + In a simple binary tree or an AVL tree, the most recently
983 * added nodes tend to be nearer the bottom, making this a *bad*
984 * way to choose which node to remove from the cache.
985 * + Randomizing the traversal order is probably a good idea. You
986 * can improve the randomization of leaf node selection by passing
987 * in pointers to nodes other than the root node each time. A
988 * pointer to any node in the tree will do. Of course, if you
989 * pass a pointer to a leaf node you'll get the same thing back.
990 *
991 * ------------------------------------------------------------------------ **
992 */
993 {
994 ubi_btNodePtr follower = NULL;
995 int whichway = ubi_trLEFT;
996
997 while( NULL != leader )
998 {
999 follower = leader;
1000 leader = follower->Link[ whichway ];
1001 if( NULL == leader )
1002 {
1003 whichway = ubi_trRevWay( whichway );
1004 leader = follower->Link[ whichway ];
1005 }
1006 }
1007
1008 return( follower );
1009 } /* ubi_btLeafNode */
1010
ubi_btModuleID(int size,char * list[])1011 int ubi_btModuleID( int size, char *list[] )
1012 /* ------------------------------------------------------------------------ **
1013 * Returns a set of strings that identify the module.
1014 *
1015 * Input: size - The number of elements in the array <list>.
1016 * list - An array of pointers of type (char *). This array
1017 * should, initially, be empty. This function will fill
1018 * in the array with pointers to strings.
1019 * Output: The number of elements of <list> that were used. If this value
1020 * is less than <size>, the values of the remaining elements are
1021 * not guaranteed.
1022 *
1023 * Notes: Please keep in mind that the pointers returned indicate strings
1024 * stored in static memory. Don't free() them, don't write over
1025 * them, etc. Just read them.
1026 * ------------------------------------------------------------------------ **
1027 */
1028 {
1029 if( size > 0 )
1030 {
1031 list[0] = ModuleID;
1032 if( size > 1 )
1033 list[1] = NULL;
1034 return( 1 );
1035 }
1036 return( 0 );
1037 } /* ubi_btModuleID */
1038
1039
1040 /* ========================================================================== */
1041