/* Copyright (C) 1998, 1999 Aladdin Enterprises.  All rights reserved.
  
  This software is provided AS-IS with no warranty, either express or
  implied.
  
  This software is distributed under license and may not be copied,
  modified or distributed except as expressly authorized under the terms
  of the license contained in the file LICENSE in this distribution.
  
  For more information about licensing, please refer to
  http://www.ghostscript.com/licensing/. For information on
  commercial licensing, go to http://www.artifex.com/licensing/ or
  contact Artifex Software, Inc., 101 Lucas Valley Road #110,
  San Rafael, CA  94903, U.S.A., +1(415)492-9861.
*/

/*$Id: idstack.h,v 1.3 2002/04/23 11:58:46 easysw Exp $ */
/* Generic dictionary stack API */

#ifndef idstack_INCLUDED
#  define idstack_INCLUDED

#include "iddstack.h"
#include "idsdata.h"
#include "istack.h"

/* Define the type of pointers into the dictionary stack. */
typedef s_ptr ds_ptr;
typedef const_s_ptr const_ds_ptr;

/* Clean up a dictionary stack after a garbage collection. */
void dstack_gc_cleanup(P1(dict_stack_t *));

/*
 * Define a special fast entry for name lookup on a dictionary stack.
 * The key is known to be a name; search the entire dict stack.
 * Return the pointer to the value slot.
 * If the name isn't found, just return 0.
 */
ref *dstack_find_name_by_index(P2(dict_stack_t *, uint));

/*
 * Define an extra-fast macro for name lookup, optimized for
 * a single-probe lookup in the top dictionary on the stack.
 * Amazingly enough, this seems to hit over 90% of the time
 * (aside from operators, of course, which are handled either with
 * the special cache pointer or with 'bind').
 */
#define dstack_find_name_by_index_inline(pds,nidx,htemp)\
  ((pds)->top_keys[htemp = dict_hash_mod_inline(dict_name_index_hash(nidx),\
     (pds)->top_npairs) + 1] == pt_tag(pt_literal_name) + (nidx) ?\
   (pds)->top_values + htemp : dstack_find_name_by_index(pds, nidx))
/*
 * Define a similar macro that only checks the top dictionary on the stack.
 */
#define if_dstack_find_name_by_index_top(pds,nidx,htemp,pvslot)\
  if ( (((pds)->top_keys[htemp = dict_hash_mod_inline(dict_name_index_hash(nidx),\
	 (pds)->top_npairs) + 1] == pt_tag(pt_literal_name) + (nidx)) ?\
	((pvslot) = (pds)->top_values + (htemp), 1) :\
	0)\
     )

#endif /* idstack_INCLUDED */
