Add ObjectStore::is_empty()

object_store.cpp

@@ -501,7 +501,19 @@ void ObjectStore::delete_data_for_object(Group *group, const StringData &object_
     }
 }
 
-
+bool ObjectStore::is_empty(const Group *group) {
+    for (size_t i = 0; i < group->size(); i++) {
+        ConstTableRef table = group->get_table(i);
+        std::string object_type = object_type_for_table_name(table->get_name());
+        if (!object_type.length()) {
+            continue;
+        }
+        if (!table->is_empty()) {
+            return false;
+        }
+    }
+    return true;
+}
 
 InvalidSchemaVersionException::InvalidSchemaVersionException(uint64_t old_version, uint64_t new_version) :
     m_old_version(old_version), m_new_version(new_version)

object_store.hpp

@@ -70,7 +70,10 @@ namespace realm {
         // deletes the table for the given type
         static void delete_data_for_object(Group *group, const StringData &object_type);
 
-      private:
+        // indicates if this group contains any objects
+        static bool is_empty(const Group *group);
+
+    private:
         // set a new schema version
         static void set_schema_version(Group *group, uint64_t version);