Add a lookup-and-return-default-value method

include/hashmap.h

@@ -12,6 +12,7 @@ struct hashmap {
 struct hashmap new_map();
 void insert_map(struct hashmap *map, const char *key, const void *value);
 const void *lookup_map(struct hashmap *map, const char *key);
+const void *lookup_map_default(struct hashmap *map, const char *key, const void *default_value);
 int exists_map(struct hashmap *map, const char *key);
 const void *remove_map(struct hashmap *map, const char *key);
 void foreach_map(struct hashmap *map, void (*cb)(const char *key, const void *value));

src/hashmap.c

@@ -60,6 +60,22 @@ const void *lookup_map(struct hashmap *map, const char *key) {
     return NULL;
 }
 
+const void *lookup_map_default(struct hashmap *map, const char *key, const void *default_value) {
+    if(key == NULL) {
+        return NULL;
+    }
+
+    int index = hash_map(key);
+
+    for(struct node *iter = map->buckets[index].head; iter != NULL; iter = iter->next) {
+        if(strcmp(iter->key, key) == 0) {
+            return iter->value;
+        }
+    }
+
+    return default_value;
+}
+
 int exists_map(struct hashmap *map, const char *key) {
     return lookup_map(map, key) != NULL;
 }