SIOFrameReader.h

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#ifndef PODIO_SIOFRAMEREADER_H
#define PODIO_SIOFRAMEREADER_H
 
#include "podio/SIOBlock.h"
#include "podio/SIOFrameData.h"
#include "podio/podioVersion.h"
#include "podio/utilities/DatamodelRegistryIOHelpers.h"
 
#include <sio/definitions.h>
 
#include <memory>
#include <string>
#include <string_view>
#include <unordered_map>
 
namespace podio {
 
class CollectionIDTable;
 
class SIOFrameReader {
 
public:
  SIOFrameReader();
  ~SIOFrameReader() = default;
 
  // non copyable
  SIOFrameReader(const SIOFrameReader&) = delete;
  SIOFrameReader& operator=(const SIOFrameReader&) = delete;
 
  /**
   * Read the next data entry from which a Frame can be constructed for the
   * given name. In case there are no more entries left for this name or in
   * case there is no data for this name, this returns a nullptr.
   */
  std::unique_ptr<podio::SIOFrameData> readNextEntry(const std::string& name);
 
  /**
   * Read the specified data entry from which a Frame can be constructed for
   * the given name. In case the entry does not exist for this name or in
   * case there is no data for this name, this returns a nullptr.
   */
  std::unique_ptr<podio::SIOFrameData> readEntry(const std::string& name, const unsigned entry);
 
  /// Returns number of entries for the given name
  unsigned getEntries(const std::string& name) const;
 
  void openFile(const std::string& filename);
 
  /// Get the build version of podio that has been used to write the current file
  podio::version::Version currentFileVersion() const {
    return m_fileVersion;
  }
 
  /// Get the names of all the availalable Frame categories in the current file(s)
  std::vector<std::string_view> getAvailableCategories() const;
 
  /// Get the datamodel definition for the given name
  const std::string_view getDatamodelDefinition(const std::string& name) const {
    return m_datamodelHolder.getDatamodelDefinition(name);
  }
 
  /// Get all names of the datamodels that ara available from this reader
  std::vector<std::string> getAvailableDatamodels() const {
    return m_datamodelHolder.getAvailableDatamodels();
  }
 
private:
  void readPodioHeader();
 
  /// read the TOC record
  bool readFileTOCRecord();
 
  void readEDMDefinitions();
 
  sio::ifstream m_stream{}; ///< The stream from which we read
 
  /// Count how many times each an entry of this name has been read already
  std::unordered_map<std::string, unsigned> m_nameCtr{};
 
  /// Table of content record where starting points of named entries can be read from
  SIOFileTOCRecord m_tocRecord{};
  /// The podio version that has been used to write the file
  podio::version::Version m_fileVersion{0};
 
  DatamodelDefinitionHolder m_datamodelHolder{};
};
 
} // namespace podio
 
#endif // PODIO_SIOFRAMEREADER_H