1 /* Licensed under LGPLv2+ - see LICENSE file for details */
10 * struct htable - private definition of a htable.
12 * It's exposed here so you can put it in your structures and so we can
13 * supply inline functions.
16 size_t (*rehash)(const void *elem, void *priv);
19 size_t elems, deleted, max, max_with_deleted;
20 /* These are the bits which are the same in all pointers. */
21 uintptr_t common_mask, common_bits;
22 uintptr_t perfect_bit;
27 * HTABLE_INITIALIZER - static initialization for a hash table.
28 * @name: name of this htable.
29 * @rehash: hash function to use for rehashing.
30 * @priv: private argument to @rehash function.
32 * This is useful for setting up static and global hash tables.
35 * // For simplicity's sake, say hash value is contents of elem.
36 * static size_t rehash(const void *elem, void *unused)
38 * return *(size_t *)elem;
40 * static struct htable ht = HTABLE_INITIALIZER(ht, rehash, NULL);
42 #define HTABLE_INITIALIZER(name, rehash, priv) \
43 { rehash, priv, 0, 0, 0, 0, 0, -1, 0, 0, &name.perfect_bit }
46 * htable_init - initialize an empty hash table.
47 * @ht: the hash table to initialize
48 * @rehash: hash function to use for rehashing.
49 * @priv: private argument to @rehash function.
51 void htable_init(struct htable *ht,
52 size_t (*rehash)(const void *elem, void *priv), void *priv);
55 * htable_init_sized - initialize an empty hash table of given size.
56 * @ht: the hash table to initialize
57 * @rehash: hash function to use for rehashing.
58 * @priv: private argument to @rehash function.
59 * @size: the number of element.
61 * If this returns false, @ht is still usable, but may need to do reallocation
62 * upon an add. If this returns true, it will not need to reallocate within
65 bool htable_init_sized(struct htable *ht,
66 size_t (*rehash)(const void *elem, void *priv),
67 void *priv, size_t size);
70 * htable_clear - empty a hash table.
71 * @ht: the hash table to clear
73 * This doesn't do anything to any pointers left in it.
75 void htable_clear(struct htable *ht);
78 * htable_copy - duplicate a hash table.
79 * @dst: the hash table to overwrite
80 * @src: the hash table to copy
82 * Only fails on out-of-memory.
84 * Equivalent to (but faster than):
85 * if (!htable_init_sized(dst, src->rehash, src->priv, 1U << src->bits))
87 * v = htable_first(src, &i);
90 * v = htable_next(src, i);
94 bool htable_copy(struct htable *dst, const struct htable *src);
97 * htable_rehash - use a hashtree's rehash function
98 * @elem: the argument to rehash()
101 size_t htable_rehash(const void *elem);
104 * htable_add - add a pointer into a hash table.
106 * @hash: the hash value of the object
107 * @p: the non-NULL pointer
109 * Also note that this can only fail due to allocation failure. Otherwise, it
112 bool htable_add(struct htable *ht, size_t hash, const void *p);
115 * htable_del - remove a pointer from a hash table
117 * @hash: the hash value of the object
120 * Returns true if the pointer was found (and deleted).
122 bool htable_del(struct htable *ht, size_t hash, const void *p);
125 * struct htable_iter - iterator or htable_first or htable_firstval etc.
127 * This refers to a location inside the hashtable.
134 * htable_firstval - find a candidate for a given hash value
135 * @htable: the hashtable
136 * @i: the struct htable_iter to initialize
137 * @hash: the hash value
139 * You'll need to check the value is what you want; returns NULL if none.
143 void *htable_firstval(const struct htable *htable,
144 struct htable_iter *i, size_t hash);
147 * htable_nextval - find another candidate for a given hash value
148 * @htable: the hashtable
149 * @i: the struct htable_iter to initialize
150 * @hash: the hash value
152 * You'll need to check the value is what you want; returns NULL if no more.
154 void *htable_nextval(const struct htable *htable,
155 struct htable_iter *i, size_t hash);
158 * htable_get - find an entry in the hash table
160 * @h: the hash value of the entry
161 * @cmp: the comparison function
162 * @ptr: the pointer to hand to the comparison function.
164 * Convenient inline wrapper for htable_firstval/htable_nextval loop.
166 static inline void *htable_get(const struct htable *ht,
168 bool (*cmp)(const void *candidate, void *ptr),
171 struct htable_iter i;
174 for (c = htable_firstval(ht,&i,h); c; c = htable_nextval(ht,&i,h)) {
175 if (cmp(c, (void *)ptr))
182 * htable_first - find an entry in the hash table
184 * @i: the struct htable_iter to initialize
186 * Get an entry in the hashtable; NULL if empty.
188 void *htable_first(const struct htable *htable, struct htable_iter *i);
191 * htable_next - find another entry in the hash table
193 * @i: the struct htable_iter to use
195 * Get another entry in the hashtable; NULL if all done.
196 * This is usually used after htable_first or prior non-NULL htable_next.
198 void *htable_next(const struct htable *htable, struct htable_iter *i);
201 * htable_prev - find the previous entry in the hash table
203 * @i: the struct htable_iter to use
205 * Get previous entry in the hashtable; NULL if all done.
207 * "previous" here only means the item that would have been returned by
208 * htable_next() before the item it returned most recently.
210 * This is usually used in the middle of (or after) a htable_next iteration and
211 * to "unwind" actions taken.
213 void *htable_prev(const struct htable *htable, struct htable_iter *i);
216 * htable_delval - remove an iterated pointer from a hash table
218 * @i: the htable_iter
220 * Usually used to delete a hash entry after it has been found with
221 * htable_firstval etc.
223 void htable_delval(struct htable *ht, struct htable_iter *i);
225 #endif /* CCAN_HTABLE_H */