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
31Void_t* dtrenew(Dt_t* dt, reg Void_t* obj)
32#else
33Void_t* dtrenew(dt, obj)
34Dt_t*		dt;
35reg 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