build: add EnTT library

include/entt/resource/loader.hpp

@@ -0,0 +1,33 @@
+#ifndef ENTT_RESOURCE_LOADER_HPP
+#define ENTT_RESOURCE_LOADER_HPP
+
+#include "../stl/memory.hpp"
+#include "../stl/utility.hpp"
+#include "fwd.hpp"
+
+namespace entt {
+
+/**
+ * @brief Transparent loader for shared resources.
+ * @tparam Type Type of resources created by the loader.
+ */
+template<typename Type>
+struct resource_loader {
+    /*! @brief Result type. */
+    using result_type = stl::shared_ptr<Type>;
+
+    /**
+     * @brief Constructs a shared pointer to a resource from its arguments.
+     * @tparam Args Types of arguments to use to construct the resource.
+     * @param args Parameters to use to construct the resource.
+     * @return A shared pointer to a resource of the given type.
+     */
+    template<typename... Args>
+    result_type operator()(Args &&...args) const {
+        return stl::make_shared<Type>(stl::forward<Args>(args)...);
+    }
+};
+
+} // namespace entt
+
+#endif