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
  16 static inline unsigned int sha1hash(const unsigned char *sha1)
  17 {
  18         /*
  19          * Equivalent to 'return *(unsigned int *)sha1;', but safe on
  20          * platforms that don't support unaligned reads.
  21          */
  22         unsigned int hash;
  23         memcpy(&hash, sha1, sizeof(hash));
  24         return hash;
  25 }
  26
  27 /* data structures */
  28
  29 struct hashmap_entry {
  30         struct hashmap_entry *next;
  31         unsigned int hash;
  32 };
  33
  34 typedef int (*hashmap_cmp_fn)(const void *entry, const void *entry_or_key,
  35                 const void *keydata);
  36
  37 struct hashmap {
  38         struct hashmap_entry **table;
  39         hashmap_cmp_fn cmpfn;
  40         unsigned int size, tablesize, grow_at, shrink_at;
  41 };
  42
  43 struct hashmap_iter {
  44         struct hashmap *map;
  45         struct hashmap_entry *next;
  46         unsigned int tablepos;
  47 };
  48
  49 /* hashmap functions */
  50
  51 extern void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
  52                 size_t initial_size);
  53 extern void hashmap_free(struct hashmap *map, int free_entries);
  54
  55 /* hashmap_entry functions */
  56
  57 static inline void hashmap_entry_init(void *entry, unsigned int hash)
  58 {
  59         struct hashmap_entry *e = entry;
  60         e->hash = hash;
  61         e->next = NULL;
  62 }
  63 extern void *hashmap_get(const struct hashmap *map, const void *key,
  64                 const void *keydata);
  65 extern void *hashmap_get_next(const struct hashmap *map, const void *entry);
  66 extern void hashmap_add(struct hashmap *map, void *entry);
  67 extern void *hashmap_put(struct hashmap *map, void *entry);
  68 extern void *hashmap_remove(struct hashmap *map, const void *key,
  69                 const void *keydata);
  70
  71 static inline void *hashmap_get_from_hash(const struct hashmap *map,
  72                 unsigned int hash, const void *keydata)
  73 {
  74         struct hashmap_entry key;
  75         hashmap_entry_init(&key, hash);
  76         return hashmap_get(map, &key, keydata);
  77 }
  78
  79 /* hashmap_iter functions */
  80
  81 extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
  82 extern void *hashmap_iter_next(struct hashmap_iter *iter);
  83 static inline void *hashmap_iter_first(struct hashmap *map,
  84                 struct hashmap_iter *iter)
  85 {
  86         hashmap_iter_init(map, iter);
  87         return hashmap_iter_next(iter);
  88 }
  89
  90 /* string interning */
  91
  92 extern const void *memintern(const void *data, size_t len);
  93 static inline const char *strintern(const char *string)
  94 {
  95         return memintern(string, strlen(string));
  96 }
  97
  98 #endif