hashmap.h

   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
  11 extern unsigned int strhash(const char *buf);
  12 extern unsigned int strihash(const char *buf);
  13 extern unsigned int memhash(const void *buf, size_t len);
  14 extern unsigned int memihash(const void *buf, size_t len);
  15 extern unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len);
  16
  17 static 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
  28 /* data structures */
  29
  30 struct hashmap_entry {
  31         struct hashmap_entry *next;
  32         unsigned int hash;
  33 };
  34
  35 typedef int (*hashmap_cmp_fn)(const void *entry, const void *entry_or_key,
  36                 const void *keydata);
  37
  38 struct hashmap {
  39         struct hashmap_entry **table;
  40         hashmap_cmp_fn cmpfn;
  41         unsigned int size, tablesize, grow_at, shrink_at;
  42 };
  43
  44 struct hashmap_iter {
  45         struct hashmap *map;
  46         struct hashmap_entry *next;
  47         unsigned int tablepos;
  48 };
  49
  50 /* hashmap functions */
  51
  52 extern void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
  53                 size_t initial_size);
  54 extern void hashmap_free(struct hashmap *map, int free_entries);
  55
  56 /* hashmap_entry functions */
  57
  58 static inline void hashmap_entry_init(void *entry, unsigned int hash)
  59 {
  60         struct hashmap_entry *e = entry;
  61         e->hash = hash;
  62         e->next = NULL;
  63 }
  64 extern void *hashmap_get(const struct hashmap *map, const void *key,
  65                 const void *keydata);
  66 extern void *hashmap_get_next(const struct hashmap *map, const void *entry);
  67 extern void hashmap_add(struct hashmap *map, void *entry);
  68 extern void *hashmap_put(struct hashmap *map, void *entry);
  69 extern void *hashmap_remove(struct hashmap *map, const void *key,
  70                 const void *keydata);
  71
  72 static 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
  80 /* hashmap_iter functions */
  81
  82 extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
  83 extern void *hashmap_iter_next(struct hashmap_iter *iter);
  84 static 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
  91 /* string interning */
  92
  93 extern const void *memintern(const void *data, size_t len);
  94 static inline const char *strintern(const char *string)
  95 {
  96         return memintern(string, strlen(string));
  97 }
  98
  99 #endif