ubi_bintree.c

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/* ========================================================================== **
 *                              ubi_BinTree.c
 *
 *  Copyright (C) 1991-1998 by Christopher R. Hertel
 *
 *  Email:  [e-mail]
 * -------------------------------------------------------------------------- **
 *
 *  This module implements a simple binary tree.
 *
 * -------------------------------------------------------------------------- **
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * -------------------------------------------------------------------------- **
 *
 * Log: ubi_BinTree.c,v
 * Revision 4.12  2004/06/06 04:51:56  crh
 * Fixed a small typo in ubi_BinTree.c (leftover testing cruft).
 * Did a small amount of formatting touchup to ubi_BinTree.h.
 *
 * Revision 4.11  2004/06/06 03:14:09  crh
 * Rewrote the ubi_btLeafNode() function.  It now takes several paths in an
 * effort to find a deeper leaf node.  There is a small amount of extra
 * overhead, but it is limited.
 *
 * Revision 4.10  2000/06/06 20:38:40  crh
 * In the ReplaceNode() function, the old node header was being copied
 * to the new node header using a byte-by-byte copy.  This was causing
 * the 'insure' software testing program to report a memory leak.  The
 * fix was to do a simple assignement: *newnode = *oldnode;
 * This quieted the (errant) memory leak reports and is probably a bit
 * faster than the bytewise copy.
 *
 * Revision 4.9  2000/01/08 23:24:30  crh
 * Clarified a variety of if( pointer ) lines, replacing them with
 * if( NULL != pointer ).  This is more correct, and I have heard
 * of at least one (obscure?) system out there that uses a non-zero
 * value for NULL.
 * Also, speed improvement in Neighbor().  It was comparing pointers
 * when it could have compared two gender values.  The pointer
 * comparison was somewhat indirect (does pointer equal the pointer
 * of the parent of the node pointed to by pointer).  Urq.
 *
 * Revision 4.8  1999/09/22 03:40:30  crh
 * Modified ubi_btTraverse() and ubi_btKillTree().  They now return an
 * unsigned long indicating the number of nodes processed.  The change
 * is subtle.  An empty tree formerly returned False, and now returns
 * zero.
 *
 * Revision 4.7  1998/10/21 06:14:42  crh
 * Fixed bugs in FirstOf() and LastOf() reported by Massimo Campostrini.
 * See function comments.
 *
 * Revision 4.6  1998/07/25 17:02:10  crh
 * Added the ubi_trNewTree() macro.
 *
 * Revision 4.5  1998/06/04 21:29:27  crh
 * Upper-cased defined constants (eg UBI_BINTREE_H) in some header files.
 * This is more "standard", and is what people expect.  Weird, eh?
 *
 * Revision 4.4  1998/06/03 17:42:46  crh
 * Further fiddling with sys_include.h.  It's now in ubi_BinTree.h which is
 * included by all of the binary tree files.
 *
 * Reminder: Some of the ubi_tr* macros in ubi_BinTree.h are redefined in
 *           ubi_AVLtree.h and ubi_SplayTree.h.  This allows easy swapping
 *           of tree types by simply changing a header.  Unfortunately, the
 *           macro redefinitions in ubi_AVLtree.h and ubi_SplayTree.h will
 *           conflict if used together.  You must either choose a single tree
 *           type, or use the underlying function calls directly.  Compare
 *           the two header files for more information.
 *
 * Revision 4.3  1998/06/02 01:28:43  crh
 * Changed ubi_null.h to sys_include.h to make it more generic.
 *
 * Revision 4.2  1998/05/20 04:32:36  crh
 * The C file now includes ubi_null.h.  See ubi_null.h for more info.
 * Also, the balance and gender fields of the node were declared as
 * signed char.  As I understand it, at least one SunOS or Solaris
 * compiler doesn't like "signed char".  The declarations were
 * wrong anyway, so I changed them to simple "char".
 *
 * Revision 4.1  1998/03/31 06:11:57  crh
 * Thomas Aglassinger sent E'mail pointing out errors in the
 * dereferencing of function pointers, and a missing typecast.
 * Thanks, Thomas!
 *
 * Revision 4.0  1998/03/10 03:19:22  crh
 * Added the AVL field 'balance' to the ubi_btNode structure.  This means
 * that all BinTree modules now use the same basic node structure, which
 * greatly simplifies the AVL module.
 * Decided that this was a big enough change to justify a new major revision
 * number.  3.0 was an error, so we're at 4.0.
 *
 * Revision 2.6  1998/01/24 06:27:46  crh
 * Added ubi_trCount() macro.
 *
 * Revision 2.5  1997/12/23 03:56:29  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 2.4  1997/07/26 04:11:10  crh
 * + Just to be annoying I changed ubi_TRUE and ubi_FALSE to ubi_trTRUE
 *   and ubi_trFALSE.
 * + There is now a type ubi_trBool to go with ubi_trTRUE and ubi_trFALSE.
 * + There used to be something called "ubi_TypeDefs.h".  I got rid of it.
 * + Added function ubi_btLeafNode().
 *
 * Revision 2.3  1997/06/03 05:16:17  crh
 * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid conflicts.
 * Also changed the interface to function InitTree().  See the comments
 * for this function for more information.
 *
 * Revision 2.2  1995/10/03 22:00:07  CRH
 * Ubisized!
 * 
 * Revision 2.1  95/03/09  23:37:10  CRH
 * Added the ModuleID static string and function.  These modules are now
 * self-identifying.
 * 
 * Revision 2.0  95/02/27  22:00:17  CRH
 * Revision 2.0 of this program includes the following changes:
 *
 *     1)  A fix to a major typo in the RepaceNode() function.
 *     2)  The addition of the static function Border().
 *     3)  The addition of the public functions FirstOf() and LastOf(), which
 *         use Border(). These functions are used with trees that allow
 *         duplicate keys.
 *     4)  A complete rewrite of the Locate() function.  Locate() now accepts
 *         a "comparison" operator.
 *     5)  Overall enhancements to both code and comments.
 *
 * I decided to give this a new major rev number because the interface has
 * changed.  In particular, there are two new functions, and changes to the
 * Locate() function.
 *
 * Revision 1.0  93/10/15  22:44:59  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_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 - June, 1991   -  Written by Christopher R. Hertel (CRH).
 *
 * ========================================================================== **
 */

#include "ubi_BinTree.h"  /* Header for this module.   */


/* ========================================================================== **
 * Static data.
 */

static char ModuleID[] = "ubi_BinTree\n\
\tRevision: 4.12\n\
\tDate: 2004/06/06 04:51:56\n\
\tAuthor: crh\n";

/* ========================================================================== **
 * Internal (private) functions.
 */

static ubi_btNodePtr qFind( ubi_btCompFunc cmp,
                            ubi_btItemPtr  FindMe,
                   register ubi_btNodePtr  p )
  /* ------------------------------------------------------------------------ **
   * This function performs a non-recursive search of a tree for a node
   * matching a specific key.  It is called "qFind()" because it is
   * faster that TreeFind (below).
   *
   *  Input:
   *     cmp      -  a pointer to the tree's comparison function.
   *     FindMe   -  a pointer to the key value for which to search.
   *     p        -  a pointer to the starting point of the search.  <p>
   *                 is considered to be the root of a subtree, and only
   *                 the subtree will be searched.
   *
   *  Output:
   *     A pointer to a node with a key that matches the key indicated by
   *     FindMe, or NULL if no such node was found.
   *
   *  Note:   In a tree that allows duplicates, the pointer returned *might
   *          not* point to the (sequentially) first occurance of the
   *          desired key.
   * ------------------------------------------------------------------------ **
   */
  {
  int tmp;

  while( (NULL != p)
      && ((tmp = ubi_trAbNormal( (*cmp)(FindMe, p) )) != ubi_trEQUAL) )
    p = p->Link[tmp];

  return( p );
  } /* qFind */

static ubi_btNodePtr TreeFind( ubi_btItemPtr  findme,
                               ubi_btNodePtr  p,
                               ubi_btNodePtr *parentp,
                               char          *gender,
                               ubi_btCompFunc CmpFunc )
  /* ------------------------------------------------------------------------ **
   * TreeFind() searches a tree for a given value (findme).  It will return a
   * pointer to the target node, if found, or NULL if the target node was not
   * found.
   *
   * TreeFind() also returns, via parameters, a pointer to the parent of the
   * target node, and a LEFT or RIGHT value indicating which child of the
   * parent is the target node.  *If the target is not found*, then these
   * values indicate the place at which the target *should be found*.  This
   * is useful when inserting a new node into a tree or searching for nodes
   * "near" the target node.
   *
   * The parameters are:
   *
   *  findme   -  is a pointer to the key information to be searched for.
   *  p        -  points to the root of the tree to be searched.
   *  parentp  -  will return a pointer to a pointer to the !parent! of the
   *              target node, which can be especially usefull if the target
   *              was not found.
   *  gender   -  returns LEFT or RIGHT to indicate which child of *parentp
   *              was last searched.
   *  CmpFunc  -  points to the comparison function.
   *
   * This function is called by ubi_btLocate() and ubi_btInsert().
   * ------------------------------------------------------------------------ **
   */
  {
  register ubi_btNodePtr tmp_p      = p;
  ubi_btNodePtr          tmp_pp     = NULL;
  char                   tmp_gender = ubi_trEQUAL;
  int                    tmp_cmp;

  while( (NULL != tmp_p)
     && (ubi_trEQUAL != (tmp_cmp = ubi_trAbNormal((*CmpFunc)(findme, tmp_p)))) )
    {
    tmp_pp     = tmp_p;                 /* Keep track of previous node. */
    tmp_gender = (char)tmp_cmp;         /* Keep track of sex of child.  */
    tmp_p      = tmp_p->Link[tmp_cmp];  /* Go to child. */
    }
  *parentp = tmp_pp;                /* Return results. */
  *gender  = tmp_gender;
  return( tmp_p );
  } /* TreeFind */

static void ReplaceNode( ubi_btNodePtr *parent,
                         ubi_btNodePtr  oldnode,
                         ubi_btNodePtr  newnode )
  /* ------------------------------------------------------------------------ **
   * Remove node oldnode from the tree, replacing it with node newnode.