xref: /titanic_51/usr/src/lib/libast/common/cdt/dtrenew.c (revision 78b2cb9a814f49b9599bf830034a12338259e0c9)
1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *           Copyright (c) 1985-2007 AT&T Knowledge Ventures            *
5 *                      and is licensed under the                       *
6 *                  Common Public License, Version 1.0                  *
7 *                      by AT&T Knowledge Ventures                      *
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 }
80