libcamera: Add ControlValidator

The new abstract ControlValidator class defines an interface that will
be used by the ControlList class to validate controls. This will allow
controls to the validated against different object types, such as Camera
and V4L2Device.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/include/control_validator.h

@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * control_validator.h - Control validator
+ */
+#ifndef __LIBCAMERA_CONTROL_VALIDATOR_H__
+#define __LIBCAMERA_CONTROL_VALIDATOR_H__
+
+#include <string>
+
+namespace libcamera {
+
+class ControlId;
+
+class ControlValidator
+{
+public:
+	virtual ~ControlValidator() {}
+
+	virtual const std::string &name() const = 0;
+	virtual bool validate(const ControlId &id) const = 0;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_CONTROL_VALIDATOR_H__ */

src/libcamera/include/meson.build

@@ -1,5 +1,6 @@
 libcamera_headers = files([
     'camera_sensor.h',
+    'control_validator.h',
     'device_enumerator.h',
     'device_enumerator_sysfs.h',
     'device_enumerator_udev.h',