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/*
* Copyright (c) 2007 Vreixo Formoso
* Copyright (c) 2014 Thomas Schmitt
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* or later as published by the Free Software Foundation.
* See COPYING file for details.
*/
#ifdef HAVE_CONFIG_H
#include "../config.h"
#endif
#include "util.h"
#include "libisofs.h"
#include <stdlib.h>
#include <string.h>
/*
* Hash table implementation
*/
struct iso_hnode
{
void *key;
void *data;
/** next node for chaining */
struct iso_hnode *next;
};
struct iso_htable
{
struct iso_hnode **table;
size_t size; /**< number of items in table */
size_t cap; /**< number of slots in table */
hash_funtion_t hash;
compare_function_t compare;
};
static
struct iso_hnode *iso_hnode_new(void *key, void *data)
{
struct iso_hnode *node = malloc(sizeof(struct iso_hnode));
if (node == NULL)
return NULL;
node->data = data;
node->key = key;
node->next = NULL;
return node;
}
/**
* Put an element in a Hash Table. The element will be identified by
* the given key, that you should use to retrieve the element again.
*
* This function allow duplicates, i.e., two items with the same key. In those
* cases, the value returned by iso_htable_get() is undefined. If you don't
* want to allow duplicates, use iso_htable_put() instead;
*
* Both the key and data pointers will be stored internally, so you should
* free the objects they point to. Use iso_htable_remove() to delete an
* element from the table.
*/
int iso_htable_add(IsoHTable *table, void *key, void *data)
{
struct iso_hnode *node;
struct iso_hnode *new;
unsigned int hash;
if (table == NULL || key == NULL) {
return ISO_NULL_POINTER;
}
new = iso_hnode_new(key, data);
if (new == NULL) {
return ISO_OUT_OF_MEM;
}
hash = table->hash(key) % table->cap;
node = table->table[hash];
table->size++;
new->next = node;
table->table[hash] = new;
return ISO_SUCCESS;
}
/**
* Like iso_htable_add(), but this doesn't allow dulpicates.
*
* @return
* 1 success, 0 if an item with the same key already exists, < 0 error
*/
int iso_htable_put(IsoHTable *table, void *key, void *data)
{
struct iso_hnode *node;
struct iso_hnode *new;
unsigned int hash;
if (table == NULL || key == NULL) {
return ISO_NULL_POINTER;
}
hash = table->hash(key) % table->cap;
node = table->table[hash];
while (node) {
if (!table->compare(key, node->key)) {
return 0;
}
node = node->next;
}
new = iso_hnode_new(key, data);
if (new == NULL) {
return ISO_OUT_OF_MEM;
}
table->size++;
new->next = table->table[hash];
table->table[hash] = new;
return ISO_SUCCESS;
}
/**
* Retrieve an element from the given table.
*
* @param table
* Hash table
* @param key
* Key of the element that will be removed
* @param data
* Will be filled with the element found. Remains untouched if no
* element with the given key is found.
* @return
* 1 if found, 0 if not, < 0 on error
*/
int iso_htable_get(IsoHTable *table, void *key, void **data)
{
struct iso_hnode *node;
unsigned int hash;
if (table == NULL || key == NULL) {
return ISO_NULL_POINTER;
}
hash = table->hash(key) % table->cap;
node = table->table[hash];
while (node) {
if (!table->compare(key, node->key)) {
if (data) {
*data = node->data;
}
return 1;
}
node = node->next;
}
return 0;
}
/**
* Remove an item with the given key from the table. In tables that allow
* duplicates, it is undefined the element that will be deleted.
*
* @param table
* Hash table
* @param key
* Key of the element that will be removed
* @param free_data
* Function that will be called passing as parameters both the key and
* the element that will be deleted. The user can use it to free the
* element. You can pass NULL if you don't want to delete the item itself.
* @return
* 1 success, 0 no element exists with the given key, < 0 error
*/
int iso_htable_remove(IsoHTable *table, void *key, hfree_data_t free_data)
{
struct iso_hnode *node, *prev;
unsigned int hash;
if (table == NULL || key == NULL) {
return ISO_NULL_POINTER;
}
hash = table->hash(key) % table->cap;
node = table->table[hash];
prev = NULL;
while (node) {
if (!table->compare(key, node->key)) {
if (free_data)
free_data(node->key, node->data);
if (prev) {
prev->next = node->next;
} else {
table->table[hash] = node->next;
}
free(node);
table->size--;
return 1;
}
prev = node;
node = node->next;
}
return 0;
}
/**
* Like remove, but instead of checking for key equality using the compare
* function, it just compare the key pointers. If the table allows duplicates,
* and you provide different keys (i.e. different pointers) to elements
* with same key (i.e. same content), this function ensure the exact element
* is removed.
*
* It has the problem that you must provide the same key pointer, and not just
* a key whose contents are equal. Moreover, if you use the same key (same
* pointer) to identify several objects, what of those are removed is
* undefined.
*
* @param table
* Hash table
* @param key
* Key of the element that will be removed
* @param free_data
* Function that will be called passing as parameters both the key and
* the element that will be deleted. The user can use it to free the
* element. You can pass NULL if you don't want to delete the item itself.
* @return
* 1 success, 0 no element exists with the given key, < 0 error
*/
int iso_htable_remove_ptr(IsoHTable *table, void *key, hfree_data_t free_data)
{
struct iso_hnode *node, *prev;
unsigned int hash;
if (table == NULL || key == NULL) {
return ISO_NULL_POINTER;
}
hash = table->hash(key) % table->cap;
node = table->table[hash];
prev = NULL;
while (node) {
if (key == node->key) {
if (free_data)
free_data(node->key, node->data);
if (prev) {
prev->next = node->next;
} else {
table->table[hash] = node->next;
}
free(node);
table->size--;
return 1;
}
prev = node;
node = node->next;
}
return 0;
}
/**
* Hash function suitable for keys that are char strings.
*/
unsigned int iso_str_hash(const void *key)
{
int i, len;
const char *p = key;
unsigned int h = 2166136261u;
len = strlen(p);
for (i = 0; i < len; i++)
h = (h * 16777619 ) ^ p[i];
return h;
}
/**
* Destroy the given hash table.
*
* Note that you're responsible to actually destroy the elements by providing
* a valid free_data function. You can pass NULL if you only want to delete
* the hash structure.
*/
void iso_htable_destroy(IsoHTable *table, hfree_data_t free_data)
{
size_t i;
struct iso_hnode *node, *tmp;
if (table == NULL) {
return;
}
for (i = 0; i < table->cap; ++i) {
node = table->table[i];
while (node) {
tmp = node->next;
if (free_data)
free_data(node->key, node->data);
free(node);
node = tmp;
}
}
free(table->table);
free(table);
}
/**
* Create a new hash table.
*
* @param size
* Number of slots in table.
* @param hash
* Function used to generate
*/
int iso_htable_create(size_t size, hash_funtion_t hash,
compare_function_t compare, IsoHTable **table)
{
IsoHTable *t;
if (size <= 0)
return ISO_WRONG_ARG_VALUE;
if (table == NULL)
return ISO_NULL_POINTER;
t = malloc(sizeof(IsoHTable));
if (t == NULL) {
return ISO_OUT_OF_MEM;
}
t->table = calloc(size, sizeof(void*));
if (t->table == NULL) {
free(t);
return ISO_OUT_OF_MEM;
}
t->cap = size;
t->size = 0;
t->hash = hash;
t->compare = compare;
*table = t;
return ISO_SUCCESS;
}