add method to merge two Json objects

Author: ellemenno

lib/src/pixeldroid/json/Json.ls

@@ -8,6 +8,25 @@ package pixeldroid.json
     {
         public static const version:String = '1.0.0';
 
+        /**
+        Merges key:value pairs of second parameter into first, overriding any duplicates.
+
+        *Note* this method does not clone non-primitive values.
+        During the merge, new keys in the first Json object will pointed to values in the second.
+        After the merge, modifying values in the second Json object would be the same as modifying them in the first.
+
+        @param j1 Target Json object; will have j2 merged into it
+        @param j2 Json object to merge into j1
+        */
+        static public function merge(j1:Json, j2:Json):void
+        {
+            Debug.assert(j1.type == Dictionary.getType(), "merge operand root data type must be Dictionary");
+            Debug.assert(j2.type == Dictionary.getType(), "merge operand root data type must be Dictionary");
+
+            for (var k:String in j2.keys)
+                j1.keys[k] = j2.keys[k];
+        }
+
         static public function fromString(value:String):Json
         {
             var j:JSON = new JSON();

test/src/spec/JsonSpec.ls

@@ -23,6 +23,7 @@ package
             it.should('retrieve native Loom types for the non-collection JSON types', get_native_types);
             it.should('retrieve array elements via items[]', get_array_elements_via_items);
             it.should('retrieve object properties via keys[]', get_object_props_via_keys);
+            it.should('provide an object merge utility', merge_objects);
         }
 
 
@@ -162,5 +163,32 @@ package
             it.expects(json.keys['key_object'].keys['object_1'].value).toEqual(1);
             it.expects(json.keys['key_nested_multitype_object'].keys['nested_2'].keys['c'].keys['z'].value).toEqual('Z');
         }
+
+        private static function merge_objects():void
+        {
+            var jsonObject1:Dictionary.<String, Object> = {};
+            var jsonObject2:Dictionary.<String, Object> = {};
+
+            jsonObject1['key_string'] = 'original value';
+
+            jsonObject2['key_string'] = 'overridden value';
+            jsonObject2['key_merged_array'] = ["merged_array"];
+            jsonObject2['key_merged_object'] = {"merged_object": true};
+
+            var j1:Json = Json.fromObject(jsonObject1);
+            var j2:Json = Json.fromObject(jsonObject2);
+
+            it.asserts(j1).isNotNull();
+            it.asserts(j2).isNotNull();
+
+            it.expects(j1.keys.length).toEqual(1);
+            it.expects(j1.keys['key_string'].value).toEqual('original value');
+
+            Json.merge(j1, j2);
+            it.expects(j1.keys.length).toEqual(3);
+            it.expects(j1.keys['key_string'].value).toEqual('overridden value');
+            it.expects(j1.keys['key_merged_array'].value).toBeA(Vector);
+            it.expects(j1.keys['key_merged_object'].value).toBeA(Dictionary);
+        }
     }
 }