ConvertHandle.h

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#ifndef DataFormats_Common_ConvertHandle_h
#define DataFormats_Common_ConvertHandle_h
 
#include "DataFormats/Common/interface/BasicHandle.h"
#include "DataFormats/Common/interface/Handle.h"
#include "DataFormats/Common/interface/Wrapper.h"
#include "FWCore/Utilities/interface/Likely.h"
 
#include <typeinfo>
#include <algorithm>
#include <memory>
 
namespace edm {
 
  namespace handleimpl {
    void throwConvertTypeError(std::type_info const& expected, std::type_info const& actual);
    std::shared_ptr<edm::HandleExceptionFactory const> makeInvalidReferenceException();
  }  // namespace handleimpl
 
  // Convert from handle-to-void to handle-to-T
  template <typename T>
  Handle<T> convert_handle(BasicHandle&& bh) noexcept(true) {
    if
      UNLIKELY(bh.failedToGet()) { return Handle<T>(std::move(bh.whyFailedFactory())); }
    void const* basicWrapper = bh.wrapper();
    if
      UNLIKELY(nullptr == basicWrapper) { return Handle<T>{handleimpl::makeInvalidReferenceException()}; }
    auto wrapper = static_cast<Wrapper<T> const*>(basicWrapper);
 
    return Handle<T>(wrapper->product(), bh.provenance());
  }
 
  template <typename T>
  Handle<T> convert_handle_check_type(BasicHandle&& bh) {
    if
      UNLIKELY(bh.failedToGet()) { return Handle<T>(std::move(bh.whyFailedFactory())); }
    void const* basicWrapper = bh.wrapper();
    if
      UNLIKELY(basicWrapper == nullptr) { return Handle<T>{handleimpl::makeInvalidReferenceException()}; }
    if
      UNLIKELY(!(bh.wrapper()->dynamicTypeInfo() == typeid(T))) {
        handleimpl::throwConvertTypeError(typeid(T), bh.wrapper()->dynamicTypeInfo());
      }
    Wrapper<T> const* wrapper = static_cast<Wrapper<T> const*>(basicWrapper);
 
    return Handle<T>(wrapper->product(), bh.provenance());
  }
 
}  // namespace edm
 
#endif