lang/map.c

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#include "map.h"
#include <stdlib.h>
#include "util.h"
#define MAP_INITIAL_CAP 32 /* must be a power of 2 in this implementation */
#define MAP_REHASH_THRESHOLD 0.7
static void init_with_cap(Map *m, size_t val_size, size_t cap);
static void rehash(Map *m);
static void init_with_cap(Map *m, size_t val_size, size_t cap) {
m->len = 0;
m->cap = cap;
m->val_size = val_size;
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void *data = xmalloc(sizeof(MapSlot) * cap + val_size * cap);
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m->slots = data;
m->vals = m->slots + cap;
for (size_t i = 0; i < cap; i++) {
m->slots[i] = (MapSlot){
.empty = true,
};
}
}
static void rehash(Map *m) {
size_t old_cap = m->cap;
MapSlot *old_slots = m->slots;
void *old_vals = m->vals;
init_with_cap(m, m->val_size, m->cap * 2);
for (size_t i = 0; i < old_cap; i++) {
if (!old_slots[i].empty) {
map_insert(m, old_slots[i].key, (uint8_t*)old_vals + m->val_size * i);
if (old_slots[i].heap_alloc)
free(old_slots[i].key);
/* TODO: Don't reallocate big keys. */
}
}
free(old_slots);
}
void map_init(Map *m, size_t val_size) {
init_with_cap(m, val_size, MAP_INITIAL_CAP);
}
void map_term(Map *m) {
for (size_t i = 0; i < m->cap; i++) {
if (!m->slots[i].empty && m->slots[i].heap_alloc)
free(m->slots[i].key);
}
free(m->slots);
}
bool map_insert(Map *m, const char *key, const void *val) {
if ((double)m->len / (double)m->cap > MAP_REHASH_THRESHOLD)
rehash(m);
size_t idx = fnv1a32(key, strlen(key)) & (m->cap - 1);
bool replaced;
for (;;) {
if (m->slots[idx].empty) {
replaced = false;
m->len++;
break;
} else {
if (streq(m->slots[idx].key, key)) {
replaced = true;
break;
} else {
if (++idx == m->cap) idx = 0;
}
}
}
m->slots[idx].empty = false;
size_t keylen = strlen(key);
if (keylen <= MAP_SMALLKEY_SIZE-1) {
strcpy(m->slots[idx].smallkey, key);
m->slots[idx].key = m->slots[idx].smallkey;
m->slots[idx].heap_alloc = false;
} else {
m->slots[idx].key = sndup(key, keylen);
m->slots[idx].heap_alloc = true;
}
memcpy((uint8_t*)m->vals + m->val_size * idx, val, m->val_size);
return replaced;
}
bool map_get(const Map *m, const char *key, void *out_val) {
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size_t idx = fnv1a32(key, strlen(key)) & (m->cap - 1);
for (;;) {
if (m->slots[idx].empty)
return false;
else {
if (streq(m->slots[idx].key, key)) {
if (out_val)
memcpy(out_val, (uint8_t*)m->vals + m->val_size * idx, m->val_size);
return true;
} else {
if (++idx == m->cap) idx = 0;
}
}
}
}