NexusLoader.h

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2025 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
 
#pragma once
 
#include "MantidDataHandling/DllConfig.h"
#include <H5Cpp.h>
#include <memory>
#include <stack>
#include <string>
#include <vector>
 
namespace Mantid::DataHandling::AlignAndFocusPowderSlim {
 
namespace NxsFieldNames {
const std::string TIME_OF_FLIGHT("event_time_offset"); // float32 in ORNL nexus files
const std::string DETID("event_id");                   // uint32 in ORNL nexus files
const std::string INDEX_ID("event_index");
} // namespace NxsFieldNames
 
using PulseROI = std::pair<size_t, size_t>;     // start and stop indices for the pulse ROIs
using EventROI = std::pair<uint64_t, uint64_t>; // start and stop indices for the events ROIs
 
class MANTID_DATAHANDLING_DLL NexusLoader {
public:
  NexusLoader(const bool is_time_filtered, const std::vector<PulseROI> &pulse_indices,
              const std::vector<std::pair<int, PulseROI>> &target_to_pulse_indices = {});
  virtual ~NexusLoader();
 
  virtual void loadData(H5::DataSet &SDS, std::unique_ptr<std::vector<uint32_t>> &data,
                        const std::vector<size_t> &offsets, const std::vector<size_t> &slabsizes);
  virtual void loadData(H5::DataSet &SDS, std::unique_ptr<std::vector<float>> &data, const std::vector<size_t> &offsets,
                        const std::vector<size_t> &slabsizes);
 
  virtual std::stack<EventROI> getEventIndexRanges(H5::Group &event_group, const uint64_t number_events,
                                                   std::unique_ptr<std::vector<uint64_t>> *event_index = nullptr) const;
  std::stack<std::pair<int, EventROI>> getEventIndexSplitRanges(H5::Group &event_group, const uint64_t number_events);
 
private:
  template <typename Type>
  void loadDataInternal(H5::DataSet &SDS, std::unique_ptr<std::vector<Type>> &data, const std::vector<size_t> &offsets,
                        const std::vector<size_t> &slabsizes) const;
  const bool m_is_time_filtered;
  const std::vector<PulseROI> m_pulse_indices;
  std::vector<std::pair<int, PulseROI>> m_target_to_pulse_indices;
  void loadEventIndex(H5::Group &event_group, std::unique_ptr<std::vector<uint64_t>> &data) const;
};
 
} // namespace Mantid::DataHandling::AlignAndFocusPowderSlim