114 lines
2.3 KiB
C
114 lines
2.3 KiB
C
/**
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* @file hash.c
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* @brief Implements a simple hash table.
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* @note Copyright (C) 2015 Richard Cochran <richardcochran@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <stdlib.h>
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#include <string.h>
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#include "hash.h"
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#define HASH_TABLE_SIZE 200
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struct node {
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char *key;
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void *data;
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struct node *next;
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};
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struct hash {
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struct node *table[HASH_TABLE_SIZE];
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};
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static unsigned int hash_function(const char* s)
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{
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unsigned int i;
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for (i = 0; *s; s++) {
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i = 131 * i + *s;
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}
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return i % HASH_TABLE_SIZE;
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}
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struct hash *hash_create(void)
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{
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struct hash *ht = calloc(1, sizeof(*ht));
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return ht;
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}
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void hash_destroy(struct hash *ht, void (*func)(void *))
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{
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unsigned int i;
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struct node *n, *next, **table = ht->table;
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for (i = 0; i < HASH_TABLE_SIZE; i++) {
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for (n = table[i] ; n; n = next) {
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next = n->next;
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if (func) {
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func(n->data);
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}
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free(n->key);
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free(n);
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}
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}
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free(ht);
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}
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int hash_insert(struct hash *ht, const char* key, void *data)
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{
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unsigned int h;
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struct node *n, **table = ht->table;
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h = hash_function(key);
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for (n = table[h] ; n; n = n->next) {
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if (!strcmp(n->key, key)) {
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/* reject duplicate keys */
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return -1;
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}
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}
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n = calloc(1, sizeof(*n));
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if (!n) {
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return -1;
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}
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n->key = strdup(key);
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if (!n->key) {
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free(n);
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return -1;
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}
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n->data = data;
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n->next = table[h];
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table[h] = n;
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return 0;
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}
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void *hash_lookup(struct hash *ht, const char* key)
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{
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unsigned int h;
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struct node *n, **table = ht->table;
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h = hash_function(key);
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for (n = table[h] ; n; n = n->next) {
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if (!strcmp(n->key, key)) {
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return n->data;
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}
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}
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return NULL;
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}
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