usr/src/lib/libast/common/cdt/dtrenew.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #include        "dthdr.h"
  23
  24
  25 /*      Renew the object at the current finger.
  26 **
  27 **      Written by Kiem-Phong Vo (5/25/96)
  28 */
  29
  30 #if __STD_C
  31 Void_t* dtrenew(Dt_t* dt, reg Void_t* obj)
  32 #else
  33 Void_t* dtrenew(dt, obj)
  34 Dt_t*           dt;
  35 reg Void_t*     obj;
  36 #endif
  37 {
  38         reg Void_t*     key;
  39         reg Dtlink_t    *e, *t, **s;
  40         reg Dtdisc_t*   disc = dt->disc;
  41
  42         UNFLATTEN(dt);
  43
  44         if(!(e = dt->data->here) || _DTOBJ(e,disc->link) != obj)
  45                 return NIL(Void_t*);
  46
  47         if(dt->data->type&(DT_STACK|DT_QUEUE|DT_LIST))
  48                 return obj;
  49         else if(dt->data->type&(DT_OSET|DT_OBAG) )
  50         {       if(!e->right )  /* make left child the new root */
  51                         dt->data->here = e->left;
  52                 else            /* make right child the new root */
  53                 {       dt->data->here = e->right;
  54
  55                         /* merge left subtree to right subtree */
  56                         if(e->left)
  57                         {       for(t = e->right; t->left; t = t->left)
  58                                         ;
  59                                 t->left = e->left;
  60                         }
  61                 }
  62         }
  63         else /*if(dt->data->type&(DT_SET|DT_BAG))*/
  64         {       s = dt->data->htab + HINDEX(dt->data->ntab,e->hash);
  65                 if((t = *s) == e)
  66                         *s = e->right;
  67                 else
  68                 {       for(; t->right != e; t = t->right)
  69                                 ;
  70                         t->right = e->right;
  71                 }
  72                 key = _DTKEY(obj,disc->key,disc->size);
  73                 e->hash = _DTHSH(dt,key,disc,disc->size);
  74                 dt->data->here = NIL(Dtlink_t*);
  75         }
  76
  77         dt->data->size -= 1;
  78         return (*dt->meth->searchf)(dt,(Void_t*)e,DT_RENEW) ? obj : NIL(Void_t*);
  79 }