getWrapperBasePtr.h

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#ifndef IOPool_Common_getWrapperBasePtr_h
#define IOPool_Common_getWrapperBasePtr_h

#include <cassert>
#include <memory>
#include "TClass.h"
#include "DataFormats/Common/interface/WrapperBase.h"

namespace edm {
  inline
  std::unique_ptr<WrapperBase> getWrapperBasePtr(void* p, int offset) {
    // A union is used to avoid possible copies during the triple cast that would otherwise be needed.   
    // std::unique_ptr<WrapperBase> edp(static_cast<WrapperBase *>(static_cast<void *>(static_cast<unsigned char *>(p) + branchInfo.offsetToWrapperBase_)));     
    union {      
      void* vp;      
      unsigned char* ucp;    
      WrapperBase* edp;      
    } pointerUnion;      
    assert(p != nullptr);
    pointerUnion.vp = p;     
    pointerUnion.ucp += offset;      
    std::unique_ptr<WrapperBase> edp(pointerUnion.edp);
    return(std::move(edp));
  }
}

#endif