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hashmap: use *_entry APIs to wrap container_of

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Using `container_of' can be verbose and choosing names for
intermediate "struct hashmap_entry" pointers is a hard problem.
So introduce "*_entry" APIs inspired by similar linked-list
APIs in the Linux kernel.

Unfortunately, `__typeof__' is not portable C, so we need an
extra parameter to specify the type.

Signed-off-by: Eric Wong <e@80x24.org>
Reviewed-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Eric Wong
2019-10-06 23:30:35 +00:00
committed by Junio C Hamano
parent 6bcbdfb277
commit f0e63c4113
6 changed files with 73 additions and 40 deletions
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40
hashmap.h
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@ -55,17 +55,15 @@
*
* if (!strcmp("print_all_by_key", action)) {
* struct long2string k, *e;
* struct hashmap_entry *ent;
* hashmap_entry_init(&k->ent, memhash(&key, sizeof(long)));
* k.key = key;
*
* flags &= ~COMPARE_VALUE;
* ent = hashmap_get(&map, &k, NULL);
* if (ent) {
* e = container_of(ent, struct long2string, ent);
* e = hashmap_get_entry(&map, &k, NULL, struct long2string, ent);
* if (e) {
* printf("first: %ld %s\n", e->key, e->value);
* while ((ent = hashmap_get_next(&map, ent))) {
* e = container_of(ent, struct long2string, ent);
* while ((e = hashmap_get_next_entry(&map, e,
* struct long2string, ent))) {
* printf("found more: %ld %s\n", e->key, e->value);
* }
* }
@ -387,6 +385,36 @@ static inline void *hashmap_iter_first(struct hashmap *map,
return hashmap_iter_next(iter);
}
/*
* returns a @pointer of @type matching @keyvar, or NULL if nothing found.
* @keyvar is a pointer of @type
* @member is the name of the "struct hashmap_entry" field in @type
*/
#define hashmap_get_entry(map, keyvar, keydata, type, member) \
container_of_or_null(hashmap_get(map, &(keyvar)->member, keydata), \
type, member)
#define hashmap_get_entry_from_hash(map, hash, keydata, type, member) \
container_of_or_null(hashmap_get_from_hash(map, hash, keydata), \
type, member)
/*
* returns the next equal @type pointer to @var, or NULL if not found.
* @var is a pointer of @type
* @member is the name of the "struct hashmap_entry" field in @type
*/
#define hashmap_get_next_entry(map, var, type, member) \
container_of_or_null(hashmap_get_next(map, &(var)->member), \
type, member)
/*
* iterate @map starting from @var, where @var is a pointer of @type
* and @member is the name of the "struct hashmap_entry" field in @type
*/
#define hashmap_for_each_entry_from(map, var, type, member) \
for (; \
var; \
var = hashmap_get_next_entry(map, var, type, member))
/*
* Disable item counting and automatic rehashing when adding/removing items.
*