2 files changed, 32 insertions, 25 deletions

diff --git a/src/hashmap.c b/src/hashmap.c
index 2787435..6b51d3e 100644
--- a/src/hashmap.c
+++ b/src/hashmap.c
@@ -215,37 +215,38 @@ hashmap_remove(struct hashmap *hm, const char *key)
     return NULL;
 }
 
+#define HASHMAP_WALK(hm, ...) \
+	struct node *node; \
+	struct node *next; \
+	for (size_t i = 0; i < hm->cur_cap; i++) { \
+		node = hm->buckets[i]; \
+		while (node) { \
+			next = node->next; \
+			__VA_ARGS__; \
+			node = next; \
+		} \
+	}
+
 void
-hashmap_walk(struct hashmap *hm, void (*fn)(const void *key, void *value))
+hashmap_walk(struct hashmap *hm, hashmap_cb cb)
 {
-    struct node *node;
-    struct node *next;
+	HASHMAP_WALK(hm, cb(node->key, node->value));
+}
 
-    for (int i=0; i < hm->cur_cap; i++) {
-        node = hm->buckets[i];
-        while (node) {
-            next = node->next;
-            fn(node->key, node->value);
-            node = next;
-        }
-    }
+void
+hashmap_destroy(struct hashmap *hm, hashmap_cb cb)
+{
+	HASHMAP_WALK(hm, cb(node->key, node->value), free(node));
+
+	free(hm->buckets);
+	free(hm);
 }
 
 void
 hashmap_free(struct hashmap *hm)
 {
-    struct node *node;
-    struct node *next;
-
-    for (int i=0; i < hm->cur_cap; i++) {
-        node = hm->buckets[i];
-        while (node) {
-            next = node->next;
-            free(node);            
-            node = next;
-        }
-    }
+	HASHMAP_WALK(hm, free(node));
 
 	free(hm->buckets);
-    free(hm);
+	free(hm);
 }
diff --git a/src/hashmap.h b/src/hashmap.h
index 981c21b..52df625 100644
--- a/src/hashmap.h
+++ b/src/hashmap.h
@@ -19,6 +19,8 @@
 #define HASHMAP_GROW_RATE 2
 #endif
 
+typedef void (hashmap_cb)(const void *key, void *value);
+
 struct hashmap {
     struct node **buckets;
     size_t init_cap;
@@ -49,9 +51,13 @@ void *hashmap_resolve(struct hashmap *hm, const char *key);
  */
 void *hashmap_remove(struct hashmap *hm, const char *key);
 
+/* Iterate over keys in the hashmap */
+void hashmap_walk(struct hashmap *hm, hashmap_cb);
+
+/* free hashmap related memory calling a function before freeing each node */
+void hashmap_destroy(struct hashmap *hm, hashmap_cb cb);
+
 /* free hashmap related memory */
 void hashmap_free(struct hashmap *hm);
 
-void hashmap_walk(struct hashmap *hm, void (*fn)(const void *key, void *value));
-
 #endif