hashmap: implement api to iterate a hashmap backwards

1 files changed, 33 insertions, 0 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);