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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* This module provides the callback functionality employed by the online sensor
* calibration algorithms.
*/
#ifndef LOCATION_LBS_CONTEXTHUB_NANOAPPS_CALIBRATION_ONLINE_CALIBRATION_COMMON_DATA_CALIBRATION_CALLBACK_H_
#define LOCATION_LBS_CONTEXTHUB_NANOAPPS_CALIBRATION_ONLINE_CALIBRATION_COMMON_DATA_CALIBRATION_CALLBACK_H_
#include "calibration/online_calibration/common_data/calibration_data.h"
namespace online_calibration {
/*
* This codebase avoids Standard Template Library (STL) containers to maximize
* its usefullness on embedded hardware with basic C++ compiler support. The
* following uses type erasure to implement callback functionality to a user's
* desired class method. The idea here is to store an object pointer by
* instantiating a class template (Callback) which implements a virtual
* interface function (CallbackInterface::Call).
*
* USAGE:
* See unit testing for a simple example of how to use this for callback
* functionality.
*/
// CalibrationType: Sets the calibration type (e.g., CalibrationDataThreeAxis).
template <class CalibrationType>
class CallbackInterface {
public:
// Interface function that is defined to implement the desired callback.
virtual void Call(const CalibrationType& cal_data,
CalibrationTypeFlags cal_update_flags) = 0;
virtual ~CallbackInterface() {}
};
// ClassCallerType: Sets the object's class type for the callback.
// CalibrationType: Sets the calibration type (e.g., CalibrationDataThreeAxis).
template <class ClassCallerType, class CalibrationType>
class Callback : public CallbackInterface<CalibrationType> {
public:
// Constructors.
Callback() = delete;
Callback(ClassCallerType* obj,
void (ClassCallerType::*func)(const CalibrationType& cal_data,
CalibrationTypeFlags cal_update_flags))
: object_ptr_(obj), function_ptr_(func) {}
// Implements the callback to the desired class-method.
void Call(const CalibrationType& cal_data,
CalibrationTypeFlags cal_update_flags) final {
(object_ptr_->*function_ptr_)(cal_data, cal_update_flags);
}
private:
// Pointer to the class that owns the callback method.
ClassCallerType* object_ptr_;
// Templated function pointer with the required function signature.
// Calibration callbacks must accept:
// 1. Constant reference to the calibration.
// 2. Bitmask indicating which calibration components have been updated.
void (ClassCallerType::*function_ptr_)(const CalibrationType& cal_data,
CalibrationTypeFlags cal_update_flags);
};
} // namespace online_calibration
#endif // LOCATION_LBS_CONTEXTHUB_NANOAPPS_CALIBRATION_ONLINE_CALIBRATION_COMMON_DATA_CALIBRATION_CALLBACK_H_
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