Move ECS to Bubel module

source/bubel/ecs/attributes.d

@@ -0,0 +1,28 @@
+/************************************************************************************************************************
+This module contain attributes used to mark components.
+Currently only two attributes are supported:
+$(LIST
+    * optional: mark component as optional for system update
+    * readonly: mark component access as read only (used for multithreading)
+)
+
+By default components are required and mutable. "const" attribute can be used insteac od readonly mark.
+
+---
+Struct EntitiesData
+{
+   Comp1[] cmp; //mutable required component
+   @readonly @optional Comp2[] cmp2; //optional read only component
+   @optional const (Comp3)[] cmp3; //same as cmp2
+}
+---
+
+Copyright: Copyright © 2018-2019, Dawid Masiukiewicz, Michał Masiukiewicz
+License: BSD 3-clause, see LICENSE file in project root folder.
+*/
+module bubel.ecs.attributes;
+
+///Used to mark optional components for system.
+enum optional = "optional";
+///Used to mark readonly components for system. "const" can be used insted.
+enum readonly = "readonly";