libcamera: Move extensible to class

The Extensible concept is a generic Class helper. To prepare for
further class helper additions, move the specific extensible
implementation and header to a more generic class header and source.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/class.cpp

@@ -2,14 +2,17 @@
 /*
  * Copyright (C) 2020, Google Inc.
  *
- * extensible.cpp - Utilities to create extensible public classes with stable ABIs
+ * class.cpp - Utilities and helpers for classes
  */
 
-#include <libcamera/extensible.h>
+#include <libcamera/class.h>
 
 /**
- * \file extensible.h
- * \brief Utilities to create extensible public classes with stable ABIs
+ * \file class.h
+ * \brief Utilities to help constructing class interfaces
+ *
+ * The extensible class can be inherited to create public classes with stable
+ * ABIs.
  */
 
 namespace libcamera {

src/libcamera/meson.build

@@ -9,6 +9,7 @@ libcamera_sources = files([
     'camera_controls.cpp',
     'camera_manager.cpp',
     'camera_sensor.cpp',
+    'class.cpp',
     'controls.cpp',
     'control_serializer.cpp',
     'control_validator.cpp',
@@ -18,7 +19,6 @@ libcamera_sources = files([
     'event_dispatcher.cpp',
     'event_dispatcher_poll.cpp',
     'event_notifier.cpp',
-    'extensible.cpp',
     'file.cpp',
     'file_descriptor.cpp',
     'formats.cpp',