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authorLennart Poettering <lennart@poettering.net>2009-06-17 03:02:19 +0200
committerLennart Poettering <lennart@poettering.net>2009-06-17 03:02:19 +0200
commita1d84e39359fed52770f9d15650aabc6bcce6910 (patch)
treed47c0b04357699a3beb63a55b12882e546d6a4b4 /src/pulsecore
parent277e8c5ce4cf055108bc8ba17d079a7318932fd2 (diff)
hashmap: implement api to iterate a hashmap backwards
Diffstat (limited to 'src/pulsecore')
-rw-r--r--src/pulsecore/hashmap.c33
-rw-r--r--src/pulsecore/hashmap.h10
2 files changed, 42 insertions, 1 deletions
diff --git a/src/pulsecore/hashmap.c b/src/pulsecore/hashmap.c
index e957c5ba..b549cb1c 100644
--- a/src/pulsecore/hashmap.c
+++ b/src/pulsecore/hashmap.c
@@ -237,6 +237,39 @@ at_end:
return NULL;
}
+void *pa_hashmap_iterate_backwards(pa_hashmap *h, void **state, const void **key) {
+ struct hashmap_entry *e;
+
+ pa_assert(h);
+ pa_assert(state);
+
+ if (*state == (void*) -1)
+ goto at_beginning;
+
+ if (!*state && !h->iterate_list_tail)
+ goto at_beginning;
+
+ e = *state ? *state : h->iterate_list_tail;
+
+ if (e->iterate_previous)
+ *state = e->iterate_previous;
+ else
+ *state = (void*) -1;
+
+ if (key)
+ *key = e->key;
+
+ return e->value;
+
+at_beginning:
+ *state = (void *) -1;
+
+ if (key)
+ *key = NULL;
+
+ return NULL;
+}
+
void* pa_hashmap_first(pa_hashmap *h) {
pa_assert(h);
diff --git a/src/pulsecore/hashmap.h b/src/pulsecore/hashmap.h
index 828e2448..f379fe3c 100644
--- a/src/pulsecore/hashmap.h
+++ b/src/pulsecore/hashmap.h
@@ -26,7 +26,8 @@
/* Simple Implementation of a hash table. Memory management is the
* user's job. It's a good idea to have the key pointer point to a
- * string in the value data. */
+ * string in the value data. The insertion order is preserved when
+ * iterating. */
typedef struct pa_hashmap pa_hashmap;
@@ -59,6 +60,9 @@ pa_bool_t pa_hashmap_isempty(pa_hashmap *h);
returned. */
void *pa_hashmap_iterate(pa_hashmap *h, void **state, const void**key);
+/* Same as pa_hashmap_iterate() but goes backwards */
+void *pa_hashmap_iterate_backwards(pa_hashmap *h, void **state, const void**key);
+
/* Remove the oldest entry in the hashmap and return it */
void *pa_hashmap_steal_first(pa_hashmap *h);
@@ -69,4 +73,8 @@ void* pa_hashmap_first(pa_hashmap *h);
#define PA_HASHMAP_FOREACH(e, h, state) \
for ((state) = NULL, (e) = pa_hashmap_iterate((h), &(state), NULL); (e); (e) = pa_hashmap_iterate((h), &(state), NULL))
+/* A macro to ease iteration through all entries, backwards */
+#define PA_HASHMAP_FOREACH_BACKWARDS(e, h, state) \
+ for ((state) = NULL, (e) = pa_hashmap_iterate_backwards((h), &(state), NULL); (e); (e) = pa_hashmap_iterate_backwards((h), &(state), NULL))
+
#endif