// This file is part of the ACTS project.

//

// Copyright (C) 2016 CERN for the benefit of the ACTS project

//

// This Source Code Form is subject to the terms of the Mozilla Public

// License, v. 2.0. If a copy of the MPL was not distributed with this

// file, You can obtain one at https://mozilla.org/MPL/2.0/.

#include "Acts/TrackFitting/KalmanFitterError.hpp"

#include "Acts/Utilities/Result.hpp"

#include <iostream>

#include <system_error>

// Example struct representing a track for demonstration purposes

struct Track {

int id;

};

// Example struct representing track parameters

struct TrackParameters {

double momentum;

};

//! [Error Enum Pattern]

enum class MyComponentError {

ErrorValue1 = 1, // All error values must be non-zero

ErrorValue2,

// ...

};

// Factory function to create std::error_code

std::error_code make_error_code(MyComponentError e);

//! [Error Enum Pattern]

//! [Usage with Result Type]

Acts::Result<Track> fitTrack(const TrackParameters& params) {

if (params.momentum < 0) {

return Acts::KalmanFitterError::UpdateFailed;

}

Track track{42};

return track; // Success

}

void processTrack() {

TrackParameters params{100.0};

// Usage

auto result = fitTrack(params);

if (!result.ok()) {

std::error_code error = result.error();

// Handle error

std::cerr << "Error: " << error.message() << std::endl;

} else {

Track track = std::move(result).value();

std::cout << "Track fitted successfully: " << track.id << std::endl;

}

}

//! [Usage with Result Type]