JsonSurfacesReader.cpp

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// This file is part of the Acts project.
//
// Copyright (C) 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/.

#include "ActsExamples/Io/Json/JsonSurfacesReader.hpp"

#include "Acts/Geometry/GeometryIdentifier.hpp"
#include "Acts/Plugins/Json/ActsJson.hpp"
#include "Acts/Plugins/Json/GeometryHierarchyMapJsonConverter.hpp"
#include "Acts/Plugins/Json/SurfaceJsonConverter.hpp"
#include "Acts/Surfaces/Surface.hpp"

#include <fstream>
#include <iostream>

namespace ActsExamples {

Acts::GeometryHierarchyMap<std::shared_ptr<Acts::Surface>>
JsonSurfacesReader::read(const JsonSurfacesReader::Options& options) {
  // Read the json file into a json object
  nlohmann::json j;
  std::ifstream in(options.inputFile);
  in >> j;
  in.close();

  using SurfaceHierachyMap =
      Acts::GeometryHierarchyMap<std::shared_ptr<Acts::Surface>>;
  using GeometryIdHelper = Acts::GeometryHierarchyMapJsonConverter<bool>;
  std::vector<SurfaceHierachyMap::InputElement> surfaceElements;

  // Walk down the path to the surface entries
  nlohmann::json jSurfaces = j;
  for (const auto& jep : options.jsonEntryPath) {
    jSurfaces = jSurfaces[jep];
  }

  // Loop over the surfaces
  surfaceElements.reserve(jSurfaces.size());
  for (const auto& jSurface : jSurfaces) {
    // Decode the surface identifier
    Acts::GeometryIdentifier geoId =
        GeometryIdHelper::decodeIdentifier(jSurface);
    auto surface = Acts::SurfaceJsonConverter::fromJson(jSurface["value"]);
    surfaceElements.emplace_back(geoId, surface);
  }
  return SurfaceHierachyMap(std::move(surfaceElements));
}

}  // namespace ActsExamples