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Implemented hash_remove_current() which removes the current iterator position

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from the hash - not yet tested.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20368 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Axel Dörfler 2007-03-11 21:18:49 +00:00
parent 824e907a2c
commit 826e857cf0
2 changed files with 70 additions and 24 deletions
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30
headers/private/kernel/util/khash.h
View File

@ -1,9 +1,16 @@
/*
** Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
** Distributed under the terms of the NewOS License.
*/
#ifndef _KERNEL_KHASH_H
#define _KERNEL_KHASH_H
/*
* Copyright 2002-2007, Haiku Inc. All rights reserved.
* Distributed under the terms of the MIT License.
*
* Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
* Distributed under the terms of the NewOS License.
*/
#ifndef _KERNEL_UTIL_KHASH_H
#define _KERNEL_UTIL_KHASH_H
#include <SupportDefs.h>
// can be allocated on the stack
typedef struct hash_iterator {
@ -23,6 +30,7 @@ struct hash_table *hash_init(uint32 table_size, int next_ptr_offset,
int hash_uninit(struct hash_table *table);
status_t hash_insert(struct hash_table *table, void *_element);
status_t hash_remove(struct hash_table *table, void *_element);
void hash_remove_current(struct hash_table *table, struct hash_iterator *iterator);
void *hash_remove_first(struct hash_table *table, uint32 *_cookie);
void *hash_find(struct hash_table *table, void *e);
void *hash_lookup(struct hash_table *table, const void *key);
@ -31,17 +39,15 @@ void hash_close(struct hash_table *table, struct hash_iterator *i, bool free_ite
void *hash_next(struct hash_table *table, struct hash_iterator *i);
void hash_rewind(struct hash_table *table, struct hash_iterator *i);
/* function ptrs must look like this:
/* function pointers must look like this:
*
* uint32 hash_func(void *e, const void *key, uint32 range);
* hash function should calculate hash on either e or key,
* depending on which one is not NULL
* depending on which one is not NULL - they also need
* to make sure the returned value is within range.
* int compare_func(void *e, const void *key);
* compare function should compare the element with
* the key, returning 0 if equal, other if not
* NOTE: compare func can be null, in which case the hash
* code will compare the key pointer with the target
* ToDo: check this!
*/
uint32 hash_hash_string(const char *str);
@ -50,4 +56,4 @@ uint32 hash_hash_string(const char *str);
}
#endif
#endif /* _KERNEL_KHASH_H */
#endif /* _KERNEL_UTIL_KHASH_H */

64
src/system/kernel/util/khash.c
View File

@ -1,16 +1,21 @@
/* Generic hash table
**
** Copyright 2001, Travis Geiselbrecht. All rights reserved.
** Distributed under the terms of the NewOS License.
*/
/*
* Copyright 2002-2007, Haiku Inc. All rights reserved.
* Distributed under the terms of the MIT License.
*
* Copyright 2001, Travis Geiselbrecht. All rights reserved.
* Distributed under the terms of the NewOS License.
*/
//! Generic hash table
#include <KernelExport.h>
#include <malloc.h>
#include <debug.h>
#include <Errors.h>
#include <string.h>
#include <util/khash.h>
#include <stdlib.h>
#include <string.h>
#define TRACE_HASH 0
#if TRACE_HASH
# define TRACE(x) dprintf x
@ -18,9 +23,9 @@
# define TRACE(x) ;
#endif
// ToDo: the hashtable is not expanded when necessary (no load factor, no nothing)
// Could try to use pools instead of malloc() for the elements - might be
// faster than the current approach.
// TODO: the hashtable is not expanded when necessary (no load factor, nothing)
// resizing should be optional, though, in case the hash is used at times
// that forbid resizing.
struct hash_table {
struct hash_element **table;
@ -123,7 +128,8 @@ hash_remove(struct hash_table *table, void *_element)
uint32 hash = table->hash_func(_element, NULL, table->table_size);
void *element, *lastElement = NULL;
for (element = table->table[hash]; element != NULL; lastElement = element, element = NEXT(table, element)) {
for (element = table->table[hash]; element != NULL;
lastElement = element, element = NEXT(table, element)) {
if (element == _element) {
if (lastElement != NULL) {
// connect the previous entry with the next one
@ -140,6 +146,40 @@ hash_remove(struct hash_table *table, void *_element)
}
void
hash_remove_current(struct hash_table *table, struct hash_iterator *iterator)
{
uint32 index = iterator->bucket;
void *element;
if (iterator->current == NULL)
panic("hash_remove_current() called too early.");
for (element = table->table[index]; index < table->table_size; index++) {
void *lastElement = NULL;
while (element != NULL) {
if (element == iterator->current) {
iterator->current = lastElement;
if (lastElement != NULL) {
// connect the previous entry with the next one
PUT_IN_NEXT(table, lastElement, NEXT(table, element));
} else {
table->table[index] = (struct hash_element *)NEXT(table,
element);
}
table->num_elements--;
return;
}
element = NEXT(table, element);
}
}
}
void *
hash_remove_first(struct hash_table *table, uint32 *_cookie)
{