A set of unique void * values with hashed membership. Use [[set]] when you want union, intersection, and difference, or when the collection stays small.

match is the same equality callback as Set (0 means equal). hash is required. There is no algebra API on this type.

Structs

typedef struct {
    void **slots;
    unsigned char *state;
    size_t cap;
    size_t len;
    size_t tombs;
    int (*match)(const void *a, const void *b);
    size_t (*hash)(const void *data);
    void (*destroy)(void *data);
} LfHashSet;

Capacity is a power of two, at least 8. The table grows when live entries plus the new insert would exceed a 3/4 load.

Functions

lf_hashset_init

cap is a hint and is rounded up. match and hash are required. Returns 0 on success, -1 on error.

int lf_hashset_init(LfHashSet *set, size_t cap,
                    int (*match)(const void *a, const void *b),
                    size_t (*hash)(const void *data),
                    void (*destroy)(void *data));

/* Usage */
int int_match(const void *a, const void *b) {
    return *(const int *)a == *(const int *)b ? 0 : 1;
}
size_t int_hash(const void *p) {
    return (size_t)*(const int *)p;
}

LfHashSet set;
lf_hashset_init(&set, 16, int_match, int_hash, NULL);

lf_hashset_destroy

Calls destroy on remaining live members, frees the tables, and zeros the handle.

void lf_hashset_destroy(LfHashSet *set);

lf_hashset_insert

Returns 0 if inserted, 1 if already a member, -1 on error.

int lf_hashset_insert(LfHashSet *set, const void *data);

lf_hashset_remove

Removes the member matching *data and writes the stored payload back through data. Does not call destroy. Returns 0 on success, -1 if missing.

int lf_hashset_remove(LfHashSet *set, void **data);

lf_hashset_is_member

Returns 1 if data is present, 0 otherwise.

int lf_hashset_is_member(const LfHashSet *set, const void *data);

Macros

#define lf_hashset_size(s) ((s)->len)