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@xxxxxxxxx>
Reviewed-by: Derrick Stolee <stolee@xxxxxxxxx>
---
diff.c | 21 +++++++++------------
diffcore-rename.c | 14 +++++---------
git-compat-util.h | 15 +++++++++++++++
hashmap.h | 40 ++++++++++++++++++++++++++++++++++------
name-hash.c | 11 +++++------
t/helper/test-hashmap.c | 12 +++++-------
6 files changed, 73 insertions(+), 40 deletions(-)
diff --git a/diff.c b/diff.c
index 0978814086..66cdf4e9ca 100644
--- a/diff.c
+++ b/diff.c
@@ -1035,10 +1035,8 @@ static void pmb_advance_or_null_multi_match(struct diff_options *o,
{
int i;
char *got_match = xcalloc(1, pmb_nr);
- struct hashmap_entry *ent;
- for (ent = &match->ent; ent; ent = hashmap_get_next(hm, ent)) {
- match = container_of(ent, struct moved_entry, ent);
+ hashmap_for_each_entry_from(hm, match, struct moved_entry, ent) {
for (i = 0; i < pmb_nr; i++) {
struct moved_entry *prev = pmb[i].match;
struct moved_entry *cur = (prev && prev->next_line) ?
@@ -1137,9 +1135,8 @@ static void mark_color_as_moved(struct diff_options *o,
for (n = 0; n < o->emitted_symbols->nr; n++) {
struct hashmap *hm = NULL;
- struct hashmap_entry *ent = NULL;
struct moved_entry *key;
- struct moved_entry *match;
+ struct moved_entry *match = NULL;
struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
enum diff_symbol last_symbol = 0;
@@ -1147,20 +1144,22 @@ static void mark_color_as_moved(struct diff_options *o,
case DIFF_SYMBOL_PLUS:
hm = del_lines;
key = prepare_entry(o, n);
- ent = hashmap_get(hm, &key->ent, NULL);
+ match = hashmap_get_entry(hm, key, NULL,
+ struct moved_entry, ent);
free(key);
break;
case DIFF_SYMBOL_MINUS:
hm = add_lines;
key = prepare_entry(o, n);
- ent = hashmap_get(hm, &key->ent, NULL);
+ match = hashmap_get_entry(hm, key, NULL,
+ struct moved_entry, ent);
free(key);
break;
default:
flipped_block = 0;
}
- if (!ent) {
+ if (!match) {
int i;
adjust_last_block(o, n, block_length);
@@ -1172,7 +1171,6 @@ static void mark_color_as_moved(struct diff_options *o,
last_symbol = l->s;
continue;
}
- match = container_of(ent, struct moved_entry, ent);
if (o->color_moved == COLOR_MOVED_PLAIN) {
last_symbol = l->s;
@@ -1193,9 +1191,8 @@ static void mark_color_as_moved(struct diff_options *o,
* The current line is the start of a new block.
* Setup the set of potential blocks.
*/
- for (; ent; ent = hashmap_get_next(hm, ent)) {
- match = container_of(ent, struct moved_entry,
- ent);
+ hashmap_for_each_entry_from(hm, match,
+ struct moved_entry, ent) {
ALLOC_GROW(pmb, pmb_nr + 1, pmb_alloc);
if (o->color_moved_ws_handling &
COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) {
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 71aa240a68..611b08f463 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -274,23 +274,19 @@ static int find_identical_files(struct hashmap *srcs,
struct diff_options *options)
{
int renames = 0;
- struct hashmap_entry *ent;
struct diff_filespec *target = rename_dst[dst_index].two;
struct file_similarity *p, *best = NULL;
int i = 100, best_score = -1;
+ unsigned int hash = hash_filespec(options->repo, target);
/*
* Find the best source match for specified destination.
*/
- ent = hashmap_get_from_hash(srcs,
- hash_filespec(options->repo, target),
- NULL);
- for (; ent; ent = hashmap_get_next(srcs, ent)) {
+ p = hashmap_get_entry_from_hash(srcs, hash, NULL,
+ struct file_similarity, entry);
+ hashmap_for_each_entry_from(srcs, p, struct file_similarity, entry) {
int score;
- struct diff_filespec *source;
-
- p = container_of(ent, struct file_similarity, entry);
- source = p->filespec;
+ struct diff_filespec *source = p->filespec;
/* False hash collision? */
if (!oideq(&source->oid, &target->oid))
diff --git a/git-compat-util.h b/git-compat-util.h
index 4cc2c8283a..4a23b9090b 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1322,4 +1322,19 @@ void unleak_memory(const void *ptr, size_t len);
#define container_of(ptr, type, member) \
((type *) ((char *)(ptr) - offsetof(type, member)))
+/*
+ * helper function for `container_of_or_null' to avoid multiple
+ * evaluation of @ptr
+ */
+static inline void *container_of_or_null_offset(void *ptr, size_t offset)
+{
+ return ptr ? (char *)ptr - offset : NULL;
+}
+
+/*
+ * like `container_of', but allows returned value to be NULL
+ */
+#define container_of_or_null(ptr, type, member) \
+ (type *)container_of_or_null_offset(ptr, offsetof(type, member))
+
#endif
diff --git a/hashmap.h b/hashmap.h
index 21bc8aff2b..cd42dcc15c 100644
--- a/hashmap.h
+++ b/hashmap.h
@@ -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.
*
diff --git a/name-hash.c b/name-hash.c
index dbacb34f50..73b83adf3d 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -702,17 +702,16 @@ void adjust_dirname_case(struct index_state *istate, char *name)
struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
{
struct cache_entry *ce;
- struct hashmap_entry *ent;
+ unsigned int hash = memihash(name, namelen);
lazy_init_name_hash(istate);
- ent = hashmap_get_from_hash(&istate->name_hash,
- memihash(name, namelen), NULL);
- while (ent) {
- ce = container_of(ent, struct cache_entry, ent);
+ ce = hashmap_get_entry_from_hash(&istate->name_hash, hash, NULL,
+ struct cache_entry, ent);
+ hashmap_for_each_entry_from(&istate->name_hash, ce,
+ struct cache_entry, ent) {
if (same_name(ce, name, namelen, icase))
return ce;
- ent = hashmap_get_next(&istate->name_hash, ent);
}
return NULL;
}
diff --git a/t/helper/test-hashmap.c b/t/helper/test-hashmap.c
index d85b8dc58e..e82cbfdee2 100644
--- a/t/helper/test-hashmap.c
+++ b/t/helper/test-hashmap.c
@@ -194,18 +194,16 @@ int cmd__hashmap(int argc, const char **argv)
free(entry);
} else if (!strcmp("get", cmd) && p1) {
- struct hashmap_entry *e;
-
/* lookup entry in hashmap */
- e = hashmap_get_from_hash(&map, hash, p1);
+ entry = hashmap_get_entry_from_hash(&map, hash, p1,
+ struct test_entry, ent);
/* print result */
- if (!e)
+ if (!entry)
puts("NULL");
- while (e) {
- entry = container_of(e, struct test_entry, ent);
+ hashmap_for_each_entry_from(&map, entry,
+ struct test_entry, ent) {
puts(get_value(entry));
- e = hashmap_get_next(&map, e);
}
} else if (!strcmp("remove", cmd) && p1) {
