* This module provides an implementation of AVL height balanced binary
* trees. (Adelson-Velskii, Landis 1962)
*
- * This header file contains the basic AVL structure and pointer typedefs
- * as well as the prototypes needed to access the functions in the AVL
- * module ubi_AVLtree. The .c file implements the low-level height balancing
- * routines that manage the AVL tree, plus all of the basic primops for
- * adding, searching for, and deleting nodes.
+ * This file implements the core of the height-balanced (AVL) tree management
+ * routines. The header file, ubi_AVLtree.h, contains function prototypes
+ * for all "exported" functions.
*
* -------------------------------------------------------------------------- **
*
* -------------------------------------------------------------------------- **
*
* Log: ubi_AVLtree.c,v
- * Revision 3.1 1997/12/18 06:26:51 crh
- * Fixed some comment bugs.
+ * Revision 2.5 1997/12/23 04:00:42 crh
+ * In this version, all constants & macros defined in the header file have
+ * the ubi_tr prefix. Also cleaned up anything that gcc complained about
+ * when run with '-pedantic -fsyntax-only -Wall'.
*
- * Revision 3.0 1997/12/08 05:38:55 crh
- * This is a new major revision level. The handling of the pointers in the
- * ubi_trNode structure was redesigned. The result is that there are fewer
- * macros floating about, and fewer cases in which values have to be
- * incremented or decremented. See ubi_BinTree for more information.
+ * Revision 2.4 1997/07/26 04:36:20 crh
+ * Andrew Leppard, aka "Grazgur", discovered that I still had my brains tied
+ * on backwards with respect to node deletion. I did some more digging and
+ * discovered that I was not changing the balance values correctly in the
+ * single rotation functions. Double rotation was working correctly because
+ * the formula for changing the balance values is the same for insertion or
+ * deletion. Not so for single rotation.
*
- * Revision 2; 1995/03/05 - 1997/12/07:
- * An overhaul to the node delete process. I had gotten it wrong in a
- * couple of places, thought I'd fixed it, and then found that I'd missed
- * something more. Thanks to Andrew Leppard for the bug report!
+ * I have tested the fix by loading the tree with over 44 thousand names,
+ * deleting 2,629 of them (all those in which the second character is 'u')
+ * and then walking the tree recursively to verify that the balance factor of
+ * each node is correct. Passed.
*
- * Revision 1; 93/10/15 - 95/03/05:
- * Added the ubi_tr defines. See ubi_BinTree.h for more info.
+ * Thanks Andrew!
+ *
+ * Also:
+ * + Changed ubi_TRUE and ubi_FALSE to ubi_trTRUE and ubi_trFALSE.
+ * + Rewrote the ubi_tr<func> macros because they weren't doing what I'd
+ * hoped they would do (see the bottom of the header file). They work now.
+ *
+ * Revision 2.3 1997/06/03 04:41:35 crh
+ * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid causing
+ * problems.
+ *
+ * Revision 2.2 1995/10/03 22:16:01 CRH
+ * Ubisized!
+ *
+ * Revision 2.1 95/03/09 23:45:59 CRH
+ * Added the ModuleID static string and function. These modules are now
+ * self-identifying.
+ *
+ * Revision 2.0 95/03/05 14:10:51 CRH
+ * This revision of ubi_AVLtree coincides with revision 2.0 of ubi_BinTree,
+ * and so includes all of the changes to that module. In addition, a bug in
+ * the node deletion process has been fixed.
+ *
+ * After rewriting the Locate() function in ubi_BinTree, I decided that it was
+ * time to overhaul this module. In the process, I discovered a bug related
+ * to node deletion. To fix the bug, I wrote function Debalance(). A quick
+ * glance will show that it is very similar to the Rebalance() function. In
+ * previous versions of this module, I tried to include the functionality of
+ * Debalance() within Rebalance(), with poor results.
+ *
+ * Revision 1.0 93/10/15 22:58:56 CRH
+ * With this revision, I have added a set of #define's that provide a single,
+ * standard API to all existing tree modules. Until now, each of the three
+ * existing modules had a different function and typedef prefix, as follows:
+ *
+ * Module Prefix
+ * ubi_BinTree ubi_bt
+ * ubi_AVLtree ubi_avl
+ * ubi_SplayTree ubi_spt
+ *
+ * To further complicate matters, only those portions of the base module
+ * (ubi_BinTree) that were superceeded in the new module had the new names.
+ * For example, if you were using ubi_AVLtree, the AVL node structure was
+ * named "ubi_avlNode", but the root structure was still "ubi_btRoot". Using
+ * SplayTree, the locate function was called "ubi_sptLocate", but the next
+ * and previous functions remained "ubi_btNext" and "ubi_btPrev".
+ *
+ * This was not too terrible if you were familiar with the modules and knew
+ * exactly which tree model you wanted to use. If you wanted to be able to
+ * change modules (for speed comparisons, etc), things could get messy very
+ * quickly.
+ *
+ * So, I have added a set of defined names that get redefined in any of the
+ * descendant modules. To use this standardized interface in your code,
+ * simply replace all occurances of "ubi_bt", "ubi_avl", and "ubi_spt" with
+ * "ubi_tr". The "ubi_tr" names will resolve to the correct function or
+ * datatype names for the module that you are using. Just remember to
+ * include the header for that module in your program file. Because these
+ * names are handled by the preprocessor, there is no added run-time
+ * overhead.
+ *
+ * Note that the original names do still exist, and can be used if you wish
+ * to write code directly to a specific module. This should probably only be
+ * done if you are planning to implement a new descendant type, such as
+ * red/black trees. CRH
*
* V0.0 - May, 1990 - Written by Christopher R. Hertel (CRH).
*
*/
static char ModuleID[] = "ubi_AVLtree\n\
-\tRevision: 3.1\n\
-\tDate: 1997/12/18 06:26:51 GMT\n\
+\tRevision: 2.5\n\
+\tDate: 1997/12/23 04:00:42\n\
\tAuthor: crh\n";
/* ========================================================================== **
tmp->Link[ubi_trPARENT] = p->Link[ubi_trPARENT];
tmp->gender = p->gender;
if(tmp->Link[ubi_trPARENT])
- (tmp->Link[ubi_trPARENT])->Link[(tmp->gender)] = tmp;
+ (tmp->Link[ubi_trPARENT])->Link[(int)(tmp->gender)] = tmp;
p->Link[ubi_trPARENT] = tmp;
p->gender = ubi_trLEFT;
if( p->Link[ubi_trRIGHT] )
p->Link[ubi_trRIGHT]->Link[ubi_trPARENT] = p;
(p->Link[ubi_trRIGHT])->gender = ubi_trRIGHT;
}
- p->balance -= tmp->balance;
+ p->balance -= ubi_trNormalize( tmp->balance );
(tmp->balance)--;
return( tmp );
} /* L1 */
tmp->Link[ubi_trPARENT] = p->Link[ubi_trPARENT];
tmp->gender = p->gender;
if(tmp->Link[ubi_trPARENT])
- (tmp->Link[ubi_trPARENT])->Link[(tmp->gender)] = tmp;
+ (tmp->Link[ubi_trPARENT])->Link[(int)(tmp->gender)] = tmp;
p->Link[ubi_trPARENT] = tmp;
p->gender = ubi_trRIGHT;
if(p->Link[ubi_trLEFT])
p->Link[ubi_trLEFT]->Link[ubi_trPARENT] = p;
p->Link[ubi_trLEFT]->gender = ubi_trLEFT;
}
- p->balance -= tmp->balance;
+ p->balance -= ubi_trNormalize( tmp->balance );
(tmp->balance)++;
return( tmp );
} /* R1 */
tmp->Link[ubi_trLEFT]->gender = ubi_trLEFT;
}
if(newroot->Link[ubi_trPARENT])
- newroot->Link[ubi_trPARENT]->Link[newroot->gender] = newroot;
+ newroot->Link[ubi_trPARENT]->Link[(int)(newroot->gender)] = newroot;
switch( newroot->balance )
{
tmp->Link[ubi_trRIGHT]->gender = ubi_trRIGHT;
}
if(newroot->Link[ubi_trPARENT])
- newroot->Link[ubi_trPARENT]->Link[newroot->gender] = newroot;
+ newroot->Link[ubi_trPARENT]->Link[(int)(newroot->gender)] = newroot;
switch( newroot->balance )
{
} /* R2 */
-static ubi_avlNodePtr Adjust( ubi_avlNodePtr p, signed char LorR )
+static ubi_avlNodePtr Adjust( ubi_avlNodePtr p, char LorR )
/* ------------------------------------------------------------------------ **
* Adjust the balance value at node *p. If necessary, rotate the subtree
* rooted at p.
*/
{
if( p->balance != LorR )
- p->balance += LorR;
+ p->balance += ubi_trNormalize(LorR);
else
{
- signed char tallerbal; /* Balance of root of the taller subtree of p. */
+ char tallerbal; /* Balance value of the root of the taller subtree of p. */
- tallerbal = p->Link[LorR]->balance;
+ tallerbal = p->Link[(int)LorR]->balance;
if( ( ubi_trEQUAL == tallerbal ) || ( p->balance == tallerbal ) )
p = ( (ubi_trLEFT==LorR) ? R1(p) : L1(p) ); /* single rotation */
else
static ubi_avlNodePtr Rebalance( ubi_avlNodePtr Root,
ubi_avlNodePtr subtree,
- signed char LorR )
+ char LorR )
/* ------------------------------------------------------------------------ **
* Rebalance the tree following an insertion.
*
static ubi_avlNodePtr Debalance( ubi_avlNodePtr Root,
ubi_avlNodePtr subtree,
- signed char LorR )
+ char LorR )
/* ------------------------------------------------------------------------ **
* Rebalance the tree following a deletion.
*
ubi_avlNodePtr dummy_p = &dummy;
if( Node1->Link[ubi_trPARENT] )
- Parent = &((Node1->Link[ubi_trPARENT])->Link[Node1->gender]);
+ Parent = &((Node1->Link[ubi_trPARENT])->Link[(int)(Node1->gender)]);
else
Parent = (ubi_avlNodePtr *)&(RootPtr->root);
ReplaceNode( Parent, Node1, dummy_p );
if( Node2->Link[ubi_trPARENT] )
- Parent = &((Node2->Link[ubi_trPARENT])->Link[Node2->gender]);
+ Parent = &((Node2->Link[ubi_trPARENT])->Link[(int)(Node2->gender)]);
else
Parent = (ubi_avlNodePtr *)&(RootPtr->root);
ReplaceNode( Parent, Node2, Node1 );
if( dummy_p->Link[ubi_trPARENT] )
- Parent = &((dummy_p->Link[ubi_trPARENT])->Link[dummy_p->gender]);
+ Parent = &((dummy_p->Link[ubi_trPARENT])->Link[(int)(dummy_p->gender)]);
else
Parent = (ubi_avlNodePtr *)&(RootPtr->root);
ReplaceNode( Parent, dummy_p, Node2 );
*/
if( DeadNode->Link[ubi_trPARENT] )
parentp = (ubi_btNodePtr *)
- &((DeadNode->Link[ubi_trPARENT])->Link[(DeadNode->gender)]);
+ &((DeadNode->Link[ubi_trPARENT])->Link[(int)(DeadNode->gender)]);
else
parentp = &( RootPtr->root );
(*parentp) = NULL;
else
{
- p = (ubi_btNodePtr)(DeadNode->Link[(DeadNode->balance)]);
- p->Link[ubi_trPARENT] = (ubi_btNodePtr)DeadNode->Link[ubi_trPARENT];
- p->gender = DeadNode->gender;
+ p = (ubi_btNodePtr)(DeadNode->Link[(int)(DeadNode->balance)]);
+ p->Link[ubi_trPARENT] = (ubi_btNodePtr)DeadNode->Link[ubi_trPARENT];
+ p->gender = DeadNode->gender;
(*parentp) = p;
}
RootPtr->root = (ubi_btNodePtr)Debalance( (ubi_avlNodePtr)RootPtr->root,
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