xenocara/app/xedit/hash.c

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2008-10-13 14:53:31 -06:00
/*
* Copyright (c) 2007,2008 Paulo Cesar Pereira de Andrade
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
* Author: Paulo Cesar Pereira de Andrade
*/
#include "util.h"
#include <stdlib.h>
#include <string.h>
/*
* This is a very simplified and adapted version of the hash tables I am
* using in a personal project. It was added to try to have a single hash
* table implementation in xedit. The lisp (for user code) version was not
* converted, but the following hastables have been converted:
* ispell.c - list of replace and ignore words
* hook.c - list of auto replace words
* internal lisp data structures:
* atoms
* strings
* packages
* opaque types
* also, all code traversing hash tables is now using
* hash_iter_first() and hash_iter_next()
* conversion isn't as good as I originally wanted, code is using hash_check
* instead of hash_get, but this is due to the code not having a basic
* { void *data; int length; } object to store string like objects
*
* Also, this hash table implementation was added mainly for the tags
* support.
*/
/*
* Prototypes
*/
static int hash_equal(hash_table *hash, hash_key *left, hash_key *right);
static unsigned int hash_data(char *value, unsigned int length);
static unsigned int hash_value(hash_key *key);
/*
* Implementation
*/
static int
hash_equal(hash_table *hash, hash_key *left, hash_key *right)
{
if (left->length == right->length) {
if (left == right)
return (1);
if (hash->compare)
return (hash->compare(left, right));
return (memcmp(left->value, right->value, left->length) == 0);
}
return (0);
}
static unsigned int
hash_data(char *value, unsigned int length)
{
char *ptr;
unsigned int i, key;
for (i = key = 0, ptr = value; i < length; i++)
key = (key << (key & 1)) ^ ptr[i];
return (key);
}
static unsigned int
hash_value(hash_key *key)
{
return (hash_data(key->value, key->length));
}
hash_table *
hash_new(unsigned int length, hash_compare compare)
{
hash_table *hash;
hash = calloc(1, sizeof(hash_table));
if (hash) {
hash->entries = calloc(length, sizeof(hash_entry *));
if (hash->entries) {
hash->length = length;
hash->compare = compare;
hash->iter.offset = -1;
}
else {
free(hash);
hash = (hash_table *)0;
}
}
return (hash);
}
hash_entry *
hash_put(hash_table *hash, hash_entry *entry)
{
unsigned int key;
hash_entry *prev, *ptr;
/* Offset in hash table vector for this entry */
key = hash_value(entry->key) % hash->length;
/* We hope this is nil for most calls */
ptr = hash->entries[key];
/* Check if clashed with another entry */
for (prev = ptr; ptr; prev = ptr, ptr = ptr->next) {
/* Replace current entry */
if (hash_equal(hash, entry->key, ptr->key)) {
/* If not trying to readd same value */
if (entry != ptr) {
if (ptr == prev)
hash->entries[key] = entry;
else
prev->next = entry;
entry->next = ptr->next;
/* Finished */
}
else
ptr = (hash_entry *)0;
goto hash_put_done;
}
}
/* Add new entry */
if (prev == (hash_entry *)0)
/* If no entry in offset */
hash->entries[key] = entry;
else
/* Add to end of clashing list */
prev->next = entry;
entry->next = (hash_entry *)0;
/* Increase sum of entries counter*/
++hash->count;
hash_put_done:
/* ptr will be nil if no entry was replaced, of tried to add
* again an entry already in the hash table */
return (ptr);
}
hash_entry *
hash_get(hash_table *hash, hash_key *name)
{
unsigned int key;
hash_entry *entry;
key = hash_value(name) % hash->length;
for (entry = hash->entries[key]; entry; entry = entry->next) {
if (hash_equal(hash, name, entry->key)) {
return (entry);
}
}
return ((hash_entry *)0);
}
hash_entry *
hash_check(hash_table *hash, char *name, unsigned int length)
{
unsigned int key;
hash_entry *entry;
key = hash_data(name, length) % hash->length;
for (entry = hash->entries[key]; entry; entry = entry->next) {
if (length == entry->key->length &&
memcmp(name, entry->key->value, length) == 0) {
return (entry);
}
}
return ((hash_entry *)0);
}
hash_entry *
hash_rem_no_free(hash_table *hash, hash_entry *entry)
{
unsigned int key;
hash_entry *ptr, *prev;
key = hash_value(entry->key) % hash->length;
for (ptr = prev = hash->entries[key]; ptr; prev = ptr, ptr = ptr->next) {
if (ptr == entry) {
--hash->count;
if (ptr == prev)
hash->entries[key] = ptr->next;
else
prev->next = ptr->next;
break;
}
}
if (ptr && ptr == hash->iter.entry)
hash->iter.entry = ptr->next;
/* If entry wasn't in hash table ptr will be nil */
return (ptr);
}
void
hash_rem(hash_table *hash, hash_entry *entry)
{
entry = hash_rem_no_free(hash, entry);
if (entry) {
free(entry->key->value);
free(entry->key);
free(entry);
}
}
void
hash_rehash(hash_table *hash, unsigned int length)
{
unsigned int i, key;
hash_entry *entry, *next, **entries;
entries = (hash_entry **)calloc(length, sizeof(hash_entry *));
if (entries) {
/* Populate the new table, note that clashes are now in reverse order */
for (i = 0; i < hash->length; i++) {
for (entry = hash->entries[i]; entry; entry = next) {
next = entry->next;
key = hash_value(entry->key) % length;
entry->next = entries[key];
entries[key] = entry;
}
}
/* Finish updating hash table */
free(hash->entries);
hash->entries = entries;
hash->length = length;
}
hash->iter.offset = -1;
}
hash_entry *
hash_iter_first(hash_table *hash)
{
hash->iter.offset = 0;
hash->iter.entry = (hash_entry *)0;
return (hash_iter_next(hash));
}
hash_entry *
hash_iter_next(hash_table *hash)
{
if (hash->iter.offset >= 0) {
if (hash->iter.entry) {
if ((hash->iter.entry = hash->iter.entry->next))
return (hash->iter.entry);
++hash->iter.offset;
}
for (; hash->iter.offset < hash->length; hash->iter.offset++) {
if ((hash->iter.entry = hash->entries[hash->iter.offset]))
return (hash->iter.entry);
}
hash->iter.entry = (hash_entry *)0;
hash->iter.offset = -1;
}
return ((hash_entry *)0);
}
void
hash_clr(hash_table *hash)
{
unsigned int i;
hash_entry *entry, *next;
/* Extra data should be free'd with the iterator */
for (i = 0; i < hash->length; i++) {
entry = hash->entries[i];
if (entry) {
for (next = entry; entry; entry = next) {
next = entry->next;
free(entry->key->value);
free(entry->key);
free(entry);
}
hash->entries[i] = (hash_entry *)0;
}
}
hash->count = 0;
hash->iter.offset = -1;
}
void
hash_del(hash_table *hash)
{
hash_clr(hash);
free(hash->entries);
free(hash);
}