Improved prefab loading a bit.

src/dawn/util/JSON.cpp

@@ -76,4 +76,27 @@ struct Color JSON::color(const json &j) {
 
   assertUnreachable("Invalid JSON type for color");
   return COLOR_WHITE;
+}
+
+void JSON::mergeObjectsRecursive(json &a, const json &b) {
+  assertTrue(a.type() == json::value_t::object, "a is not an object");
+  assertTrue(b.type() == json::value_t::object, "b is not an object");
+
+  for(auto &item : b.items()) {
+    auto &key = item.key();
+    auto &value = item.value();
+
+    if(a.contains(key)) {
+      if(
+        a[key].type() == json::value_t::object &&
+        value.type() == json::value_t::object
+      ) {
+        mergeObjectsRecursive(a[key], value);
+      } else {
+        a[key] = json(value);
+      }
+    } else {
+      a[key] = json(value);
+    }
+  }
 }

src/dawn/util/JSON.hpp

@@ -25,5 +25,20 @@ namespace Dawn {
        * @return Parsed color.
        */
       static struct Color color(const json &j);
+
+      /**
+       * Merges all objects in the given JSON object into the first object, 
+       * recursively.
+       * 
+       * e.g. if; &a is { a: { b: 1, c: 2 }, d: 3 }
+       *          &b is { a: { b: 4, d: 5 }, e: 4 }
+       * 
+       * The output will become;
+       *   { a: { b: 4, c: 2, d: 5 }, e: 4 }
+       * 
+       * @param a JSON object to merge into.
+       * @param b JSON object to merge from.
+       */
+      static void mergeObjectsRecursive(json &a, const json &b);
   };
 }