Twelfth batch for 2.14
[git/git.git] / hashmap.h
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1#ifndef HASHMAP_H
2#define HASHMAP_H
3
4/*
5 * Generic implementation of hash-based key-value mappings.
6 * See Documentation/technical/api-hashmap.txt.
7 */
8
9/* FNV-1 functions */
10
11extern unsigned int strhash(const char *buf);
12extern unsigned int strihash(const char *buf);
13extern unsigned int memhash(const void *buf, size_t len);
14extern unsigned int memihash(const void *buf, size_t len);
f75619bd 15extern unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len);
6a364ced 16
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17static inline unsigned int sha1hash(const unsigned char *sha1)
18{
19 /*
20 * Equivalent to 'return *(unsigned int *)sha1;', but safe on
21 * platforms that don't support unaligned reads.
22 */
23 unsigned int hash;
24 memcpy(&hash, sha1, sizeof(hash));
25 return hash;
26}
27
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28/* data structures */
29
30struct hashmap_entry {
31 struct hashmap_entry *next;
32 unsigned int hash;
33};
34
35typedef int (*hashmap_cmp_fn)(const void *entry, const void *entry_or_key,
36 const void *keydata);
37
38struct hashmap {
39 struct hashmap_entry **table;
40 hashmap_cmp_fn cmpfn;
41 unsigned int size, tablesize, grow_at, shrink_at;
0607e100 42 unsigned disallow_rehash : 1;
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43};
44
45struct hashmap_iter {
46 struct hashmap *map;
47 struct hashmap_entry *next;
48 unsigned int tablepos;
49};
50
51/* hashmap functions */
52
53extern void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
54 size_t initial_size);
55extern void hashmap_free(struct hashmap *map, int free_entries);
56
57/* hashmap_entry functions */
58
b6aad994 59static inline void hashmap_entry_init(void *entry, unsigned int hash)
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60{
61 struct hashmap_entry *e = entry;
62 e->hash = hash;
63 e->next = NULL;
64}
65extern void *hashmap_get(const struct hashmap *map, const void *key,
66 const void *keydata);
67extern void *hashmap_get_next(const struct hashmap *map, const void *entry);
68extern void hashmap_add(struct hashmap *map, void *entry);
69extern void *hashmap_put(struct hashmap *map, void *entry);
70extern void *hashmap_remove(struct hashmap *map, const void *key,
71 const void *keydata);
72
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73static inline void *hashmap_get_from_hash(const struct hashmap *map,
74 unsigned int hash, const void *keydata)
75{
76 struct hashmap_entry key;
77 hashmap_entry_init(&key, hash);
78 return hashmap_get(map, &key, keydata);
79}
80
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81int hashmap_bucket(const struct hashmap *map, unsigned int hash);
82
83/*
84 * Disallow/allow rehashing of the hashmap.
85 * This is useful if the caller knows that the hashmap
86 * needs multi-threaded access. The caller is still
87 * required to guard/lock searches and inserts in a
88 * manner appropriate to their usage. This simply
89 * prevents the table from being unexpectedly re-mapped.
90 *
91 * If is up to the caller to ensure that the hashmap is
92 * initialized to a reasonable size to prevent poor
93 * performance.
94 *
95 * When value=1, prevent future rehashes on adds and deleted.
96 * When value=0, allow future rehahses. This DOES NOT force
97 * a rehash now.
98 */
99static inline void hashmap_disallow_rehash(struct hashmap *map, unsigned value)
100{
101 map->disallow_rehash = value;
102}
103
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104/* hashmap_iter functions */
105
106extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
107extern void *hashmap_iter_next(struct hashmap_iter *iter);
108static inline void *hashmap_iter_first(struct hashmap *map,
109 struct hashmap_iter *iter)
110{
111 hashmap_iter_init(map, iter);
112 return hashmap_iter_next(iter);
113}
114
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115/* string interning */
116
117extern const void *memintern(const void *data, size_t len);
118static inline const char *strintern(const char *string)
119{
120 return memintern(string, strlen(string));
121}
122
6a364ced 123#endif