BranchReadHelper.h

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/***********************************************************************************\
* (c) Copyright 2026 CERN for the benefit of the LHCb and ATLAS collaborations      *
*                                                                                   *
* This software is distributed under the terms of the Apache version 2 licence,     *
* copied verbatim in the file "LICENSE".                                            *
*                                                                                   *
* In applying this licence, CERN does not waive the privileges and immunities       *
* granted to it by virtue of its status as an Intergovernmental Organization        *
* or submit itself to any jurisdiction.                                             *
\***********************************************************************************/
#pragma once
 
#include <GaudiKernel/DataObject.h>
#include <TBranch.h>
#include <gsl/pointers>
#include <memory>

 
namespace Gaudi::details {
 
  class BranchReadHelper final {
  public:
    explicit BranchReadHelper( gsl::not_null<TBranch*> b );
    BranchReadHelper( const BranchReadHelper& other )            = delete;
    BranchReadHelper& operator=( const BranchReadHelper& other ) = delete;
    BranchReadHelper( BranchReadHelper&& other ) noexcept;
    BranchReadHelper& operator=( BranchReadHelper&& other ) noexcept;
 
    std::unique_ptr<DataObject> adoptValue();
 
    ~BranchReadHelper();
 
  private:
    TBranch* m_branch{ nullptr };
    void*    m_store{ nullptr };
 
    DataObject* ( *m_extractor )( void* ) = nullptr;
  };
 
} // namespace Gaudi::details