WebSVN – HelenOS-historic – Blame – /uspace/trunk/libadt/generic/hash_table.c

Rev	Author	Line No.	Line
996	cejka	1	/*
		2	* Copyright (C) 2006 Jakub Jermar
		3	* All rights reserved.
		4	*
		5	* Redistribution and use in source and binary forms, with or without
		6	* modification, are permitted provided that the following conditions
		7	* are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright
		10	* notice, this list of conditions and the following disclaimer.
		11	* - Redistributions in binary form must reproduce the above copyright
		12	* notice, this list of conditions and the following disclaimer in the
		13	* documentation and/or other materials provided with the distribution.
		14	* - The name of the author may not be used to endorse or promote products
		15	* derived from this software without specific prior written permission.
		16	*
		17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		27	*/
		28
		29	/*
		30	* This is an implementation of generic chained hash table.
		31	*/
		32
		33	#include <hash_table.h>
		34	#include <list.h>
		35	#include <unistd.h>
		36	#include <malloc.h>
		37	#include <assert.h>
997	cejka	38	#include <stdio.h>
		39	#include <string.h>
996	cejka	40
		41	/** Create chained hash table.
		42	*
		43	* @param h Hash table structure. Will be initialized by this call.
		44	* @param m Number of slots in the hash table.
		45	* @param max_keys Maximal number of keys needed to identify an item.
		46	* @param op Hash table operations structure.
997	cejka	47	* @return true on success
996	cejka	48	*/
997	cejka	49	int hash_table_create(hash_table_t h, hash_count_t m, hash_count_t max_keys, hash_table_operations_t op)
996	cejka	50	{
997	cejka	51	hash_count_t i;
996	cejka	52
997	cejka	53	assert(h);
		54	assert(op && op->hash && op->compare);
		55	assert(max_keys > 0);
996	cejka	56
1202	jermar	57	h->entry = malloc(m * sizeof(link_t));
996	cejka	58	if (!h->entry) {
997	cejka	59	printf("cannot allocate memory for hash table\n");
		60	return false;
996	cejka	61	}
1202	jermar	62	memset((void ) h->entry, 0, m sizeof(link_t));
996	cejka	63
		64	for (i = 0; i < m; i++)
		65	list_initialize(&h->entry[i]);
		66
		67	h->entries = m;
		68	h->max_keys = max_keys;
		69	h->op = op;
997	cejka	70	return true;
996	cejka	71	}
		72
		73	/** Insert item into hash table.
		74	*
		75	* @param h Hash table.
		76	* @param hey Array of all keys necessary to compute hash index.
		77	* @param item Item to be inserted into the hash table.
		78	*/
997	cejka	79	void hash_table_insert(hash_table_t h, unsigned long key[], link_t item)
996	cejka	80	{
		81	hash_index_t chain;
		82
997	cejka	83	assert(item);
		84	assert(h && h->op && h->op->hash && h->op->compare);
996	cejka	85
		86	chain = h->op->hash(key);
997	cejka	87	assert(chain < h->entries);
996	cejka	88
		89	list_append(item, &h->entry[chain]);
		90	}
		91
		92	/** Search hash table for an item matching keys.
		93	*
		94	* @param h Hash table.
		95	* @param key Array of all keys needed to compute hash index.
		96	*
		97	* @return Matching item on success, NULL if there is no such item.
		98	*/
997	cejka	99	link_t hash_table_find(hash_table_t h, unsigned long key[])
996	cejka	100	{
		101	link_t *cur;
		102	hash_index_t chain;
		103
997	cejka	104	assert(h && h->op && h->op->hash && h->op->compare);
996	cejka	105
		106	chain = h->op->hash(key);
997	cejka	107	assert(chain < h->entries);
996	cejka	108
		109	/*
		110	* The hash table is not redundant.
		111	* Check if the keys are not in place already.
		112	*/
		113	for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
		114	if (h->op->compare(key, h->max_keys, cur)) {
		115	/*
		116	* The entry is there.
		117	*/
		118	return cur;
		119	}
		120	}
		121
		122	return NULL;
		123	}
		124
		125	/** Remove all matching items from hash table.
		126	*
		127	* For each removed item, h->remove_callback() is called.
		128	*
		129	* @param h Hash table.
		130	* @param key Array of keys that will be compared against items of the hash table.
		131	* @param keys Number of keys in the 'key' array.
		132	*/
997	cejka	133	void hash_table_remove(hash_table_t *h, unsigned long key[], hash_count_t keys)
996	cejka	134	{
		135	hash_index_t chain;
		136	link_t *cur;
		137
997	cejka	138	assert(h && h->op && h->op->hash && h->op->compare && h->op->remove_callback);
		139	assert(keys <= h->max_keys);
996	cejka	140
		141	if (keys == h->max_keys) {
		142
		143	/*
		144	* All keys are known, hash_table_find() can be used to find the entry.
		145	*/
		146
		147	cur = hash_table_find(h, key);
		148	if (cur) {
		149	list_remove(cur);
		150	h->op->remove_callback(cur);
		151	}
		152	return;
		153	}
		154
		155	/*
		156	* Fewer keys were passed.
		157	* Any partially matching entries are to be removed.
		158	*/
		159	for (chain = 0; chain < h->entries; chain++) {
		160	for (cur = h->entry[chain].next; cur != &h->entry[chain]; cur = cur->next) {
		161	if (h->op->compare(key, keys, cur)) {
		162	link_t *hlp;
		163
		164	hlp = cur;
		165	cur = cur->prev;
		166
		167	list_remove(hlp);
		168	h->op->remove_callback(hlp);
		169
		170	continue;
		171	}
		172	}
		173	}
		174	}

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(root)/uspace/trunk/libadt/generic/hash_table.c – Rev 1202