ubi_splaytree.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* ========================================================================== **
 *                              ubi_SplayTree.c
 *
 *  Copyright (C) 1993-1998 by Christopher R. Hertel
 *
 *  Email: [e-mail]
 * -------------------------------------------------------------------------- **
 *
 *  This module implements "splay" trees.  Splay trees are binary trees
 *  that are rearranged (splayed) whenever a node is accessed.  The
 *  splaying process *tends* to make the tree bushier (improves balance),
 *  and the nodes that are accessed most frequently *tend* to be closer to
 *  the top.
 *
 *  References: "Self-Adjusting Binary Search Trees", by Daniel Sleator and
 *              Robert Tarjan.  Journal of the Association for Computing
 *              Machinery Vol 32, No. 3, July 1985 pp. 652-686
 *
 *    See also: http://www.cs.cmu.edu/~sleator/
 *
 * -------------------------------------------------------------------------- **
 *
 *  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_SplayTree.c,v 
 * Revision 4.5  2000/01/08 23:26:49  crh
 * Added ubi_trSplay() macro, which does a type cast for us.
 *
 * Revision 4.4  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 4.3  1998/06/03 17:45:05  crh
 * Further fiddling with sys_include.h.  It's now in ubi_BinTree.h which is
 * included by all of the binary tree files.
 *
 * Also fixed some warnings produced by lint on Irix 6.2, which doesn't seem
 * to like syntax like this:
 *
 *   if( (a = b) )
 *
 * The fix was to change lines like the above to:
 *
 *   if( 0 != (a=b) )
 *
 * Which means the same thing.
 *
 * 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 4.2  1998/06/02 01:29:14  crh
 * Changed ubi_null.h to sys_include.h to make it more generic.
 *
 * Revision 4.1  1998/05/20 04:37:54  crh
 * The C file now includes ubi_null.h.  See ubi_null.h for more info.
 *
 * Revision 4.0  1998/03/10 03:41:33  crh
 * Minor comment changes.  The revision number is now 4.0 to match the
 * BinTree and AVLtree modules.
 *
 * Revision 2.7  1998/01/24 06:37:08  crh
 * Added a URL for more information.
 *
 * Revision 2.6  1997/12/23 04:01:12  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 2.5  1997/07/26 04:15:42  crh
 * + Cleaned up a few minor syntax annoyances that gcc discovered for me.
 * + Changed ubi_TRUE and ubi_FALSE to ubi_trTRUE and ubi_trFALSE.
 *
 * Revision 2.4  1997/06/03 04:42:21  crh
 * Changed TRUE and FALSE to ubi_TRUE and ubi_FALSE to avoid causing
 * problems.
 *
 * Revision 2.3  1995/10/03 22:19:07  CRH
 * Ubisized!
 * Also, added the function ubi_sptSplay().
 *
 * Revision 2.1  95/03/09  23:54:42  CRH
 * Added the ModuleID static string and function.  These modules are now
 * self-identifying.
 * 
 * Revision 2.0  95/02/27  22:34:46  CRH
 * This module was updated to match the interface changes made to the
 * ubi_BinTree module.  In particular, the interface to the Locate() function
 * has changed.  See ubi_BinTree for more information on changes and new
 * functions.
 *
 * The revision number was also upped to match ubi_BinTree.
 *
 * Revision 1.1  93/10/18  20:35:16  CRH
 * I removed the hard-coded logical device names from the include file
 * specifications.  CRH
 *
 * Revision 1.0  93/10/15  23:00:15  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
 *
 * Revision 0.1  93/04/25  22:03:32  CRH
 * Simply changed the <exec/types.h> #include reference the .c file to
 * use <stdlib.h> instead.  The latter is portable, the former is not.
 *
 * Revision 0.0  93/04/21  23:05:52  CRH
 * Initial version, written by Christopher R. Hertel.
 * This module implements Splay Trees using the ubi_BinTree module as a basis.
 *
 * ========================================================================== **
 */

#include "ubi_SplayTree.h"  /* Header for THIS module.   */

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

static char ModuleID[] = "ubi_SplayTree\n\
\tRevision: 4.5 \n\
\tDate: 2000/01/08 23:26:49 \n\
\tAuthor: crh \n";


/* ========================================================================== **
 * Private functions...
 */

static void Rotate( ubi_btNodePtr p )
  /* ------------------------------------------------------------------------ **
   * This function performs a single rotation, moving node *p up one level
   * in the tree.
   *
   *  Input:    p - a pointer to an ubi_btNode in a tree.
   *
   *  Output:   None.
   *
   *  Notes:    This implements a single rotation in either direction (left
   *            or right).  This is the basic building block of all splay
   *            tree rotations.
   * ------------------------------------------------------------------------ **
   */
  {
  ubi_btNodePtr parentp;
  ubi_btNodePtr tmp;
  char          way;
  char          revway;

  parentp = p->Link[ubi_trPARENT];    /* Find parent. */

  if( parentp )                 /* If no parent, then we're already the root. */
    {
    way    = p->gender;
    revway = ubi_trRevWay(way);
    tmp    = p->Link[(int)revway];

    parentp->Link[(int)way] = tmp;
    if( tmp )
      {
      tmp->Link[ubi_trPARENT] = parentp;
      tmp->gender             = way;
      }

    tmp                   = parentp->Link[ubi_trPARENT];
    p->Link[ubi_trPARENT] = tmp;
    p->gender             = parentp->gender;
    if( tmp )
      tmp->Link[(int)(p->gender)] = p;

    parentp->Link[ubi_trPARENT] = p;
    parentp->gender             = revway;
    p->Link[(int)revway]        = parentp;
    }
  } /* Rotate */

static ubi_btNodePtr Splay( ubi_btNodePtr SplayWithMe )
  /* ------------------------------------------------------------------------ **
   * Move the node indicated by SplayWithMe to the root of the tree by
   * splaying the tree.
   *
   *  Input:  SplayWithMe - A pointer to an ubi_btNode within a tree.
   *
   *  Output: A pointer to the root of the splay tree (i.e., the same as
   *          SplayWithMe).
   * ------------------------------------------------------------------------ **
   */
  {
  ubi_btNodePtr parent;

  while( NULL != (parent = SplayWithMe->Link[ubi_trPARENT]) )
    {
    if( parent->gender == SplayWithMe->gender )       /* Zig-Zig */
      Rotate( parent );
    else
      {
      if( ubi_trEQUAL != parent->gender )             /* Zig-Zag */
        Rotate( SplayWithMe );
      }
    Rotate( SplayWithMe );                            /* Zig */
    } /* while */
  return( SplayWithMe );
  } /* Splay */

/* ========================================================================== **
 * Exported utilities.
 */

ubi_trBool ubi_sptInsert( ubi_btRootPtr  RootPtr,