/*  $Id$

    Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        wielemak@science.uva.nl
    WWW:           http://www.swi-prolog.org
    Copyright (C): 1985-2007, University of Amsterdam

    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 library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    As a special exception, if you link this library with other files,
    compiled with a Free Software compiler, to produce an executable, this
    library does not by itself cause the resulting executable to be covered
    by the GNU General Public License. This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

#ifndef HASH_H_INCLUDED
#define HASH_H_INCLUDED

typedef struct ptr_hash_node
{ struct ptr_hash_node *next;		/* next in chain */
  void *value;				/* hashed value */
} ptr_hash_node;


typedef struct ptr_hash
{ int entries;				/* # chains  */
  int shift;				/* shift for pointers */
  ptr_hash_node **chains;		/* hash chains */
} ptr_hash;

ptr_hash       *new_ptr_hash(int entries, int shift);
void		destroy_ptr_hash(ptr_hash *hash);
int		add_ptr_hash(ptr_hash *hash, void *value);
int		for_ptr_hash(ptr_hash *hash,
			     int (*func)(ptr_hash_node *node, void *closure),
			     void *closure);

		 /*******************************
		 *	       ATOMS		*
		 *******************************/

typedef ptr_hash atom_hash;
#define new_atom_hash(entries) new_ptr_hash(entries, ATOM_HASH_SHIFT)
#define destroy_atom_hash(hash) destroy_ptr_hash(hash)
#define add_atom_hash(hash, atom) add_ptr_hash(hash, (void*)(atom))
#define for_atom_hash for_ptr_hash


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SWI-Prolog note: Atoms are integers shifted by LMASK_BITS (7)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define POINTER_HASH_SHIFT 3
#define ATOM_HASH_SHIFT 7
#define atom_hash(a) (((unsigned long)a)>>ATOM_HASH_SHIFT)

#endif /*HASH_H_INCLUDED*/