Wrapper.h

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#ifndef DataFormats_Common_Wrapper_h
#define DataFormats_Common_Wrapper_h

/*----------------------------------------------------------------------

Wrapper: A template wrapper around EDProducts to hold the product ID.

----------------------------------------------------------------------*/

#include "DataFormats/Common/interface/WrapperBase.h"
#include "DataFormats/Common/interface/WrapperDetail.h"
#include "DataFormats/Common/interface/CMS_CLASS_VERSION.h"
#include "DataFormats/Provenance/interface/ProductID.h"
#include "FWCore/Utilities/interface/Visibility.h"

#include <algorithm>
#include <cassert>
#include <memory>
#include <string>
#include <typeinfo>

namespace edm {
  template <typename T>
  class Wrapper : public WrapperBase {
  public:
    typedef T value_type;
    typedef T wrapped_type;  // used with the dictionary to identify Wrappers
    Wrapper() : WrapperBase(), present(false), obj() {}
    explicit Wrapper(std::unique_ptr<T> ptr);
    Wrapper(Wrapper<T> const& rh) = delete;             // disallow copy construction
    Wrapper<T>& operator=(Wrapper<T> const&) = delete;  // disallow assignment

    template <typename... Args>
    explicit Wrapper(Emplace, Args&&...);
    ~Wrapper() override {}
    T const* product() const { return (present ? &obj : nullptr); }
    T const* operator->() const { return product(); }

    T& bareProduct() { return obj; }

    //these are used by FWLite
    static std::type_info const& productTypeInfo() { return typeid(T); }
    static std::type_info const& typeInfo() { return typeid(Wrapper<T>); }

    // the constructor takes ownership of T*
    Wrapper(T*);

    //Used by ROOT storage
    CMS_CLASS_VERSION(3)

  private:
    bool isPresent_() const override { return present; }
    std::type_info const& dynamicTypeInfo_() const override { return typeid(T); }
    std::type_info const& wrappedTypeInfo_() const override { return typeid(Wrapper<T>); }

    std::type_info const& valueTypeInfo_() const override;
    std::type_info const& memberTypeInfo_() const override;
    bool isMergeable_() const override;
    bool mergeProduct_(WrapperBase const* newProduct) override;
    bool hasIsProductEqual_() const override;
    bool isProductEqual_(WrapperBase const* newProduct) const override;
    bool hasSwap_() const override;
    void swapProduct_(WrapperBase* newProduct) override;

    void do_fillView(ProductID const& id,
                     std::vector<void const*>& pointers,
                     FillViewHelperVector& helpers) const override;
    void do_setPtr(std::type_info const& iToType, unsigned long iIndex, void const*& oPtr) const override;
    void do_fillPtrVector(std::type_info const& iToType,
                          std::vector<unsigned long> const& iIndices,
                          std::vector<void const*>& oPtr) const override;

    std::shared_ptr<soa::TableExaminerBase> tableExaminer_() const override;

  private:
    bool present;
    T obj;
  };

  template <typename T>
  Wrapper<T>::Wrapper(std::unique_ptr<T> ptr) : WrapperBase(), present(ptr.get() != nullptr), obj() {
    if (present) {
      obj = std::move(*ptr);
    }
  }

  template <typename T>
  template <typename... Args>
  Wrapper<T>::Wrapper(Emplace, Args&&... args) : WrapperBase(), present(true), obj(std::forward<Args>(args)...) {}

  template <typename T>
  Wrapper<T>::Wrapper(T* ptr) : WrapperBase(), present(ptr != 0), obj() {
    std::unique_ptr<T> temp(ptr);
    if (present) {
      obj = std::move(*ptr);
    }
  }

  template <typename T>
  inline std::type_info const& Wrapper<T>::valueTypeInfo_() const {
    return detail::getValueType<T>()();
  }

  template <typename T>
  inline std::type_info const& Wrapper<T>::memberTypeInfo_() const {
    return detail::getMemberType<T>()();
  }

  template <typename T>
  inline bool Wrapper<T>::isMergeable_() const {
    return detail::getHasMergeFunction<T>()();
  }

  template <typename T>
  inline bool Wrapper<T>::mergeProduct_(WrapperBase const* newProduct) {
    Wrapper<T> const* wrappedNewProduct = dynamic_cast<Wrapper<T> const*>(newProduct);
    assert(wrappedNewProduct != nullptr);
    return detail::doMergeProduct<T>()(obj, wrappedNewProduct->obj);
  }

  template <typename T>
  inline bool Wrapper<T>::hasIsProductEqual_() const {
    return detail::getHasIsProductEqual<T>()();
  }

  template <typename T>
  inline bool Wrapper<T>::isProductEqual_(WrapperBase const* newProduct) const {
    Wrapper<T> const* wrappedNewProduct = dynamic_cast<Wrapper<T> const*>(newProduct);
    assert(wrappedNewProduct != nullptr);
    return detail::doIsProductEqual<T>()(obj, wrappedNewProduct->obj);
  }

  template <typename T>
  inline bool Wrapper<T>::hasSwap_() const {
    return detail::getHasSwapFunction<T>()();
  }

  template <typename T>
  inline void Wrapper<T>::swapProduct_(WrapperBase* newProduct) {
    Wrapper<T>* wrappedNewProduct = dynamic_cast<Wrapper<T>*>(newProduct);
    assert(wrappedNewProduct != nullptr);
    detail::doSwapProduct<T>()(obj, wrappedNewProduct->obj);
  }

  namespace soa {
    template <class T>
    struct MakeTableExaminer {
      static std::shared_ptr<edm::soa::TableExaminerBase> make(void const*) {
        return std::shared_ptr<edm::soa::TableExaminerBase>{};
      }
    };
  }  // namespace soa
  template <typename T>
  inline std::shared_ptr<edm::soa::TableExaminerBase> Wrapper<T>::tableExaminer_() const {
    return soa::MakeTableExaminer<T>::make(&obj);
  }

}  // namespace edm

#include "DataFormats/Common/interface/WrapperView.icc"

#endif