/*
** Copyright (C) 1993-2000, 2004-2005 The University of Melbourne.
** This file may only be copied under the terms of the GNU Library General
** Public License - see the file COPYING.LIB in the Mercury distribution.
*/

/*
** Hash table handling module.
**
** This file supplies data manipulation routines to other modules;
** it does not store any data itself. Its routines are generic,
** applicable to the storage of any kind of data structure with
** a primary key and a hash function on it.
*/

#include	"mercury_imp.h" 

#include	<stdio.h>
#include	"mercury_std.h"
#include	"mercury_dlist.h"
#include	"mercury_hash_table.h"

void 
MR_ht_init_table(MR_Hash_Table *table)
{
	int	i;

	table->MR_ht_store = MR_GC_NEW_ARRAY(MR_Dlist *, table->MR_ht_size);

	for (i = 0; i < table->MR_ht_size; i++) {
		table->MR_ht_store[i] = NULL;
	}
}

void *
MR_ht_lookup_table(const MR_Hash_Table *table, const void *key)
{
	MR_Dlist	*ptr;
	int		h;

	h = MR_tablehash(table)(key);

#ifdef	MR_HASHDEBUG
	if (! (0 <= h && h < table->MR_ht_size)) {
		fprintf(stderr, "internal error: bad hash index in "
			"lookup_table: %d, table size %d\n", 
			h, table->MR_ht_size);
	}
#endif

	MR_for_dlist (ptr, table->MR_ht_store[h]) {
		if (MR_tableequal(table)(key,
			MR_tablekey(table)(MR_dlist_data(ptr))))
		{
			return (void *) MR_dlist_data(ptr);
		}
	}

	return NULL;
}

const void *
MR_ht_insert_table(const MR_Hash_Table *table, void *entry)
{
	MR_Dlist	*ptr;
	const void	*key;
	int		h;

	key = MR_tablekey(table)(entry);
	h   = MR_tablehash(table)(key);

#ifdef	MR_HASHDEBUG
	if (! (0 <= h && h < table->MR_ht_size)) {
		fprintf(stderr, "internal error: bad hash index in "
			"lookup_table: %d, table size %d\n", 
			h, table->MR_ht_size);
	}
#endif

	MR_for_dlist (ptr, table->MR_ht_store[h]) {
		if (MR_tableequal(table)(key,
			MR_tablekey(table)(MR_dlist_data(ptr))))
		{
			return MR_dlist_data(ptr);
		}
	}

	table->MR_ht_store[h] = MR_dlist_addhead(table->MR_ht_store[h], entry);
	return NULL;
}

MR_Dlist *
MR_ht_get_all_entries(const MR_Hash_Table *table)
{
	MR_Dlist	*list;
	int		i;

	list = MR_dlist_makelist0();
	for (i = 0; i < table->MR_ht_size; i++) {
		MR_dlist_addndlist(list, table->MR_ht_store[i]);
	}

	return list;
}

void
MR_ht_process_all_entries(const MR_Hash_Table *table, void f(const void *))
{
	MR_Dlist	*ptr;
	int		i;

	for (i = 0; i < table->MR_ht_size; i++) {
		MR_for_dlist (ptr, table->MR_ht_store[i]) {
			f(MR_dlist_data(ptr));
		}
	}
}

int 
MR_ht_str_to_int(const char *cs)
{
	int		h;
	const char	*s;

	s = cs;
	for (h = 0; *s != '\0'; s++) {
		h = (h << 1) + *s;
	}

	if (h < 0) {
		h = -h;
	}

	return h;
}