/*
 *
 * h a s h  . h			-- Hash Tables
 *
 * Copyright © 1994-2007 Erick Gallesio - I3S-CNRS/ESSI <eg@unice.fr>
 *
 +=============================================================================
 ! This code is a rewriting of the file tclHash.c of the Tcl
 ! distribution.  Current writing is more modular, independent of Tcl
 ! and (I hope) simpler to use. Multi-word keys which exists in the
 ! Tcl implementation have been droped here. Furthermore, current
 ! implementation of the API also takes into account the fact that we
 ! have a GC approach. The original code from which this file is
 ! derived was copyrighted as follow:
 !
 ! Copyright (c) 1991-1993 The Regents of the University of California.
 ! Copyright (c) 1994 Sun Microsystems, Inc.
 +=============================================================================
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 *
 *           Author: Erick Gallesio [eg@kaolin.unice.fr]
 *    Creation date: 17-Jan-1994 17:49
 * Last file update: 11-Apr-2007 17:58 (eg)
 */


#define SMALL_HASH_TABLE   4
#define REBUILD_MULTIPLIER 3	/* When there are this many entries per bucket, */
				/* on average,  make the table larger		*/

#define HASH_OBARRAY_FLAG   1	/* Only for the symbol table 	  */
#define HASH_VAR_FLAG	    2 	/* For modules (keys are symbols) */
#define HASH_SCM_FLAG	    3	/* For secheme hash tables   	  */

typedef enum {hash_system, hash_eqp, hash_stringp, hash_general} hash_type;

struct hash_table_obj {
  stk_header header;
  SCM *buckets;
  SCM static_buckets[SMALL_HASH_TABLE];
  int num_buckets;
  int num_entries;
  int rebuild_size;
  int down_shift;
  int mask;
  /* Following slots are used only for "user" hash tables */
  hash_type type;
  SCM comparison;
  SCM hash_fct;
};

#define HASHP(o) 		(BOXED_TYPE_EQ((o), tc_hash_table))
#define HASH_BUCKETS(h)		(((struct hash_table_obj *) (h))->buckets)
#define HASH_SBUCKETS(h)	(((struct hash_table_obj *) (h))->static_buckets)
#define HASH_NBUCKETS(h)	(((struct hash_table_obj *) (h))->num_buckets)
#define HASH_NENTRIES(h)	(((struct hash_table_obj *) (h))->num_entries)
#define HASH_NEWSIZE(h)		(((struct hash_table_obj *) (h))->rebuild_size)
#define HASH_SHIFT(h)		(((struct hash_table_obj *) (h))->down_shift)
#define HASH_MASK(h)		(((struct hash_table_obj *) (h))->mask)

#define HASH_TYPE(h)		(((struct hash_table_obj *) (h))->type)
#define HASH_COMPAR(h)		(((struct hash_table_obj *) (h))->comparison)
#define HASH_HASH(h)		(((struct hash_table_obj *) (h))->hash_fct)


void STk_hashtable_init(struct hash_table_obj *h, int flag);



/*
 * Function for accessing symbol/keyword hash table. This function is of
 * little interest except for the obarrays. Don't use it but the
 * higher level interface instead.
 */
SCM STk_hash_intern_symbol(struct hash_table_obj *h, char *s,
			   SCM (*create)(char *s));

/*
 * Function for accessing module hash table. Don't use them but the
 * higher level interface instead.
 */
SCM STk_hash_get_variable(struct hash_table_obj *h, SCM v, int *index);
void STk_hash_set_variable(struct hash_table_obj *h, SCM v, SCM value);
void STk_hash_set_alias(struct hash_table_obj *h, SCM v, SCM value);

/*
 * Utilities on hash tables
 */
SCM STk_hash_keys(struct hash_table_obj *h);


int STk_init_hash(void);