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| | #include "cache.h"
#include "prefix-map.h"
static int map_cmp(const void *unused_cmp_data,
const void *entry,
const void *entry_or_key,
const void *unused_keydata)
{
const struct prefix_map_entry *a = entry;
const struct prefix_map_entry *b = entry_or_key;
return a->prefix_length != b->prefix_length ||
strncmp(a->name, b->name, a->prefix_length);
}
static void add_prefix_entry(struct hashmap *map, const char *name,
size_t prefix_length, struct prefix_item *item)
{
struct prefix_map_entry *result = xmalloc(sizeof(*result));
result->name = name;
result->prefix_length = prefix_length;
result->item = item;
hashmap_entry_init(result, memhash(name, prefix_length));
hashmap_add(map, result);
}
static void init_prefix_map(struct prefix_map *prefix_map,
int min_prefix_length, int max_prefix_length)
{
hashmap_init(&prefix_map->map, map_cmp, NULL, 0);
prefix_map->min_length = min_prefix_length;
prefix_map->max_length = max_prefix_length;
}
static void add_prefix_item(struct prefix_map *prefix_map,
struct prefix_item *item)
{
struct prefix_map_entry *e = xmalloc(sizeof(*e)), *e2;
int j;
e->item = item;
e->name = e->item->name;
for (j = prefix_map->min_length; j <= prefix_map->max_length; j++) {
if (!isascii(e->name[j])) {
free(e);
break;
}
e->prefix_length = j;
hashmap_entry_init(e, memhash(e->name, j));
e2 = hashmap_get(&prefix_map->map, e, NULL);
if (!e2) {
/* prefix is unique so far */
e->item->prefix_length = j;
hashmap_add(&prefix_map->map, e);
break;
}
if (!e2->item)
continue; /* non-unique prefix */
if (j != e2->item->prefix_length)
BUG("unexpected prefix length: %d != %d",
(int)j, (int)e2->item->prefix_length);
/* skip common prefix */
for (; j < prefix_map->max_length && e->name[j]; j++) {
if (e->item->name[j] != e2->item->name[j])
break;
add_prefix_entry(&prefix_map->map, e->name, j + 1,
NULL);
}
/* e2 no longer refers to a unique prefix */
if (j < prefix_map->max_length && e2->name[j]) {
/* found a new unique prefix for e2's item */
e2->item->prefix_length = j + 1;
add_prefix_entry(&prefix_map->map, e2->name, j + 1,
e2->item);
}
else
e2->item->prefix_length = 0;
e2->item = NULL;
if (j < prefix_map->max_length && e->name[j]) {
/* found a unique prefix for the item */
e->item->prefix_length = j + 1;
add_prefix_entry(&prefix_map->map, e->name, j + 1,
e->item);
} else {
/* item has no (short enough) unique prefix */
e->item->prefix_length = 0;
free(e);
}
break;
}
}
void find_unique_prefixes(struct prefix_item **list, size_t nr,
int min_length, int max_length)
{
int i;
struct prefix_map prefix_map;
init_prefix_map(&prefix_map, min_length, max_length);
for (i = 0; i < nr; i++)
add_prefix_item(&prefix_map, list[i]);
hashmap_free(&prefix_map.map, 1);
}
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