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