hashmap: allow memihash computation to be continued
[git/git.git] / hashmap.h
CommitLineData
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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;
42};
43
44struct hashmap_iter {
45 struct hashmap *map;
46 struct hashmap_entry *next;
47 unsigned int tablepos;
48};
49
50/* hashmap functions */
51
52extern void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
53 size_t initial_size);
54extern void hashmap_free(struct hashmap *map, int free_entries);
55
56/* hashmap_entry functions */
57
b6aad994 58static inline void hashmap_entry_init(void *entry, unsigned int hash)
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59{
60 struct hashmap_entry *e = entry;
61 e->hash = hash;
62 e->next = NULL;
63}
64extern void *hashmap_get(const struct hashmap *map, const void *key,
65 const void *keydata);
66extern void *hashmap_get_next(const struct hashmap *map, const void *entry);
67extern void hashmap_add(struct hashmap *map, void *entry);
68extern void *hashmap_put(struct hashmap *map, void *entry);
69extern void *hashmap_remove(struct hashmap *map, const void *key,
70 const void *keydata);
71
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72static inline void *hashmap_get_from_hash(const struct hashmap *map,
73 unsigned int hash, const void *keydata)
74{
75 struct hashmap_entry key;
76 hashmap_entry_init(&key, hash);
77 return hashmap_get(map, &key, keydata);
78}
79
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80/* hashmap_iter functions */
81
82extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
83extern void *hashmap_iter_next(struct hashmap_iter *iter);
84static inline void *hashmap_iter_first(struct hashmap *map,
85 struct hashmap_iter *iter)
86{
87 hashmap_iter_init(map, iter);
88 return hashmap_iter_next(iter);
89}
90
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91/* string interning */
92
93extern const void *memintern(const void *data, size_t len);
94static inline const char *strintern(const char *string)
95{
96 return memintern(string, strlen(string));
97}
98
6a364ced 99#endif