1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Generic associative array implementation.
3  *
4  * See Documentation/core-api/assoc_array.rst for information.
5  *
6  * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
7  * Written by David Howells (dhowells@redhat.com)
8  */
9 
10 #ifndef _LINUX_ASSOC_ARRAY_H
11 #define _LINUX_ASSOC_ARRAY_H
12 
13 #ifdef CONFIG_ASSOCIATIVE_ARRAY
14 
15 #include <linux/types.h>
16 
17 #define ASSOC_ARRAY_KEY_CHUNK_SIZE BITS_PER_LONG /* Key data retrieved in chunks of this size */
18 
19 /*
20  * Generic associative array.
21  */
22 struct assoc_array {
23 	struct assoc_array_ptr	*root;		/* The node at the root of the tree */
24 	unsigned long		nr_leaves_on_tree;
25 };
26 
27 /*
28  * Operations on objects and index keys for use by array manipulation routines.
29  */
30 struct assoc_array_ops {
31 	/* Method to get a chunk of an index key from caller-supplied data */
32 	unsigned long (*get_key_chunk)(const void *index_key, int level);
33 
34 	/* Method to get a piece of an object's index key */
35 	unsigned long (*get_object_key_chunk)(const void *object, int level);
36 
37 	/* Is this the object we're looking for? */
38 	bool (*compare_object)(const void *object, const void *index_key);
39 
40 	/* How different is an object from an index key, to a bit position in
41 	 * their keys? (or -1 if they're the same)
42 	 */
43 	int (*diff_objects)(const void *object, const void *index_key);
44 
45 	/* Method to free an object. */
46 	void (*free_object)(void *object);
47 };
48 
49 /*
50  * Access and manipulation functions.
51  */
52 struct assoc_array_edit;
53 
assoc_array_init(struct assoc_array * array)54 static inline void assoc_array_init(struct assoc_array *array)
55 {
56 	array->root = NULL;
57 	array->nr_leaves_on_tree = 0;
58 }
59 
60 extern int assoc_array_iterate(const struct assoc_array *array,
61 			       int (*iterator)(const void *object,
62 					       void *iterator_data),
63 			       void *iterator_data);
64 extern void *assoc_array_find(const struct assoc_array *array,
65 			      const struct assoc_array_ops *ops,
66 			      const void *index_key);
67 extern void assoc_array_destroy(struct assoc_array *array,
68 				const struct assoc_array_ops *ops);
69 extern struct assoc_array_edit *assoc_array_insert(struct assoc_array *array,
70 						   const struct assoc_array_ops *ops,
71 						   const void *index_key,
72 						   void *object);
73 extern void assoc_array_insert_set_object(struct assoc_array_edit *edit,
74 					  void *object);
75 extern struct assoc_array_edit *assoc_array_delete(struct assoc_array *array,
76 						   const struct assoc_array_ops *ops,
77 						   const void *index_key);
78 extern struct assoc_array_edit *assoc_array_clear(struct assoc_array *array,
79 						  const struct assoc_array_ops *ops);
80 extern void assoc_array_apply_edit(struct assoc_array_edit *edit);
81 extern void assoc_array_cancel_edit(struct assoc_array_edit *edit);
82 extern int assoc_array_gc(struct assoc_array *array,
83 			  const struct assoc_array_ops *ops,
84 			  bool (*iterator)(void *object, void *iterator_data),
85 			  void *iterator_data);
86 
87 #endif /* CONFIG_ASSOCIATIVE_ARRAY */
88 #endif /* _LINUX_ASSOC_ARRAY_H */
89