HelicalTrackLinearizer.hpp

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// This file is part of the Acts project.
//
// Copyright (C) 2019-2023 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 http://mozilla.org/MPL/2.0/.

#pragma once

#include "Acts/Definitions/Algebra.hpp"
#include "Acts/EventData/TrackParameters.hpp"
#include "Acts/Geometry/GeometryContext.hpp"
#include "Acts/MagneticField/MagneticFieldContext.hpp"
#include "Acts/MagneticField/MagneticFieldProvider.hpp"
#include "Acts/MagneticField/NullBField.hpp"
#include "Acts/Propagator/EigenStepper.hpp"
#include "Acts/Propagator/Propagator.hpp"
#include "Acts/Utilities/Result.hpp"
#include "Acts/Vertexing/LinearizedTrack.hpp"

namespace Acts {

template <typename propagator_t,
          typename propagator_options_t = PropagatorOptions<>>
class HelicalTrackLinearizer {
 public:
  using Propagator_t = propagator_t;

  struct State {
    State(MagneticFieldProvider::Cache fieldCacheIn)
        : fieldCache(std::move(fieldCacheIn)) {}
    MagneticFieldProvider::Cache fieldCache;
  };

  struct Config {
    Config(std::shared_ptr<const MagneticFieldProvider> bIn,
           std::shared_ptr<const Propagator_t> prop)
        : bField(std::move(bIn)), propagator(std::move(prop)) {}

    Config(std::shared_ptr<const Propagator_t> prop)
        : bField{std::make_shared<NullBField>()}, propagator(std::move(prop)) {}

    // The magnetic field
    std::shared_ptr<const MagneticFieldProvider> bField;
    // The propagator
    std::shared_ptr<const Propagator_t> propagator;

    ActsScalar targetTolerance = 1e-12;
  };

  HelicalTrackLinearizer(const Config& config,
                         std::unique_ptr<const Logger> _logger =
                             getDefaultLogger("HelTrkLinProp", Logging::INFO))
      : m_cfg(config), m_logger{std::move(_logger)} {}

  Result<LinearizedTrack> linearizeTrack(const BoundTrackParameters& params,
                                         double linPointTime,
                                         const Surface& perigeeSurface,
                                         const Acts::GeometryContext& gctx,
                                         const Acts::MagneticFieldContext& mctx,
                                         State& state) const;

 private:
  const Config m_cfg;

  std::unique_ptr<const Logger> m_logger;

  const Logger& logger() const { return *m_logger; }
};

}  // namespace Acts

#include "HelicalTrackLinearizer.ipp"