1/***********************************************************************
2*                                                                      *
3*               This software is part of the ast package               *
4*          Copyright (c) 1985-2011 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/*	Change search method.
25**
26**	Written by Kiem-Phong Vo (05/25/96)
27*/
28
29#if __STD_C
30Dtmethod_t* dtmethod(Dt_t* dt, Dtmethod_t* meth)
31#else
32Dtmethod_t* dtmethod(dt, meth)
33Dt_t*		dt;
34Dtmethod_t*	meth;
35#endif
36{
37	reg Dtlink_t	*list, *r;
38	reg Dtdisc_t*	disc = dt->disc;
39	reg Dtmethod_t*	oldmeth = dt->meth;
40
41	if(!meth || meth->type == oldmeth->type)
42		return oldmeth;
43
44	if(disc->eventf &&
45	   (*disc->eventf)(dt,DT_METH,(Void_t*)meth,disc) < 0)
46		return NIL(Dtmethod_t*);
47
48	dt->data->minp = 0;
49
50	/* get the list of elements */
51	list = dtflatten(dt);
52
53	if(dt->data->type&(DT_LIST|DT_STACK|DT_QUEUE) )
54		dt->data->head = NIL(Dtlink_t*);
55	else if(dt->data->type&(DT_SET|DT_BAG) )
56	{	if(dt->data->ntab > 0)
57			(*dt->memoryf)(dt,(Void_t*)dt->data->htab,0,disc);
58		dt->data->ntab = 0;
59		dt->data->htab = NIL(Dtlink_t**);
60	}
61
62	dt->data->here = NIL(Dtlink_t*);
63	dt->data->type = (dt->data->type&~(DT_METHODS|DT_FLATTEN)) | meth->type;
64	dt->meth = meth;
65	if(dt->searchf == oldmeth->searchf)
66		dt->searchf = meth->searchf;
67
68	if(meth->type&(DT_LIST|DT_STACK|DT_QUEUE) )
69	{	if(!(oldmeth->type&(DT_LIST|DT_STACK|DT_QUEUE)) )
70		{	if((r = list) )
71			{	reg Dtlink_t*	t;
72				for(t = r->right; t; r = t, t = t->right )
73					t->left = r;
74				list->left = r;
75			}
76		}
77		dt->data->head = list;
78	}
79	else if(meth->type&(DT_OSET|DT_OBAG))
80	{	dt->data->size = 0;
81		while(list)
82		{	r = list->right;
83			(*meth->searchf)(dt,(Void_t*)list,DT_RENEW);
84			list = r;
85		}
86	}
87	else if(!((meth->type&DT_BAG) && (oldmeth->type&DT_SET)) )
88	{	int	rehash;
89		if((meth->type&(DT_SET|DT_BAG)) && !(oldmeth->type&(DT_SET|DT_BAG)))
90			rehash = 1;
91		else	rehash = 0;
92
93		dt->data->size = dt->data->loop = 0;
94		while(list)
95		{	r = list->right;
96			if(rehash)
97			{	reg Void_t* key = _DTOBJ(list,disc->link);
98				key = _DTKEY(key,disc->key,disc->size);
99				list->hash = _DTHSH(dt,key,disc,disc->size);
100			}
101			(void)(*meth->searchf)(dt,(Void_t*)list,DT_RENEW);
102			list = r;
103		}
104	}
105
106	return oldmeth;
107}
108