dtflatten.c   [plain text]

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*           Copyright (c) 1985-2007 AT&T Knowledge Ventures            *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                      by AT&T Knowledge Ventures                      *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#include	"dthdr.h"

/*	Flatten a dictionary into a linked list.
**	This may be used when many traversals are likely.
**
**	Written by Kiem-Phong Vo (5/25/96).
*/

#if __STD_C
Dtlink_t* dtflatten(Dt_t* dt)
#else
Dtlink_t* dtflatten(dt)
Dt_t*	dt;
#endif
{
	reg Dtlink_t	*t, *r, *list, *last, **s, **ends;

	/* already flattened */
	if(dt->data->type&DT_FLATTEN )
		return dt->data->here;

	list = last = NIL(Dtlink_t*);
	if(dt->data->type&(DT_SET|DT_BAG))
	{	for(ends = (s = dt->data->htab) + dt->data->ntab; s < ends; ++s)
		{	if((t = *s) )
			{	if(last)
					last->right = t;
				else	list = last = t;
				while(last->right)
					last = last->right;
				*s = last;
			}
		}
	}
	else if(dt->data->type&(DT_LIST|DT_STACK|DT_QUEUE) )
		list = dt->data->head;
	else if((r = dt->data->here) ) /*if(dt->data->type&(DT_OSET|DT_OBAG))*/
	{	while((t = r->left) )
			RROTATE(r,t);
		for(list = last = r, r = r->right; r; last = r, r = r->right)
		{	if((t = r->left) )
			{	do	RROTATE(r,t);
				while((t = r->left) );

				last->right = r;
			}
		}
	}

	dt->data->here = list;
	dt->data->type |= DT_FLATTEN;

	return list;
}