RefCore.h

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#ifndef canvas_Persistency_Common_RefCore_h
#define canvas_Persistency_Common_RefCore_h
// vim: set sw=2 expandtab :

#include "canvas/Persistency/Provenance/ProductID.h"

namespace art {

  class EDProductGetter;

  class RefCore {
  public:
    struct RefCoreTransients {
      constexpr RefCoreTransients() = default;
      explicit RefCoreTransients(void const* prodPtr,
                                 EDProductGetter const* prodGetter) noexcept;

      mutable void const* itemPtr_{nullptr};
      EDProductGetter const* prodGetter_{nullptr};
    };

    constexpr RefCore() = default;
    RefCore(ProductID const& theId,
            void const* prodPtr,
            EDProductGetter const* prodGetter);

    constexpr bool
    isNonnull() const noexcept
    {
      return id_.isValid();
    }
    constexpr bool
    isNull() const noexcept
    {
      return !isNonnull();
    }
    constexpr bool
    operator!() const noexcept
    {
      return isNull();
    }

    // Checks if collection is in memory or available in the Event; no
    // type checking is done.  Actually fetches the collection data
    // product using the productGetter()->getIt() if it has not been
    // fetched yet.
    bool isAvailable() const;

    constexpr ProductID
    id() const noexcept
    {
      return id_;
    }
    void const* productPtr() const noexcept;

    // Used by isAvailable() to actually read the data product
    // using EDProductGeter::getIt().
    EDProductGetter const* productGetter() const noexcept;

    // Used by RefCoreStreamer on read to set itemPtr_ to the nullptr.
    void setProductPtr(void const* prodPtr) const noexcept;

    // Used by RefCoreStreamer on read.
    // Note: prodGetter_ is actually a Group for art,
    //       and a BranchData or AssnsBranchData for gallery.
    void setProductGetter(EDProductGetter const*) noexcept;
    void swap(RefCore& other);

  private:
    ProductID id_{};
    RefCoreTransients transients_{};
  };

  constexpr bool
  operator==(RefCore const& lhs, RefCore const& rhs) noexcept
  {
    return lhs.id() == rhs.id();
  }

  constexpr bool
  operator!=(RefCore const& lhs, RefCore const& rhs) noexcept
  {
    return !(lhs == rhs);
  }

  constexpr bool
  operator<(RefCore const& lhs, RefCore const& rhs) noexcept
  {
    return lhs.id() < rhs.id();
  }

  void swap(RefCore&, RefCore&);

} // namespace art

#endif /* canvas_Persistency_Common_RefCore_h */

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