object_ref.h

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// === object_ref.h ====================================================================================================
//                                               Sen Infrastructure
//                   Released under the Apache License v2.0 (SPDX-License-Identifier Apache-2.0).
//                                    See the LICENSE.txt file for more information.
//                   © Airbus SAS, Airbus Helicopters, and Airbus Defence and Space SAU/GmbH/SAS.
// =====================================================================================================================
 
#ifndef SEN_CORE_OBJ_OBJECT_REF_H
#define SEN_CORE_OBJ_OBJECT_REF_H
 
// sen
#include "sen/core/obj/interest.h"
#include "sen/core/obj/object_provider.h"
 
namespace sen
{


template <typename T>
class ObjectRef final: public ObjectProviderListener
{
public:  // types
  using Callback = std::function<void()>;
 
public:
  SEN_NOCOPY_NOMOVE(ObjectRef)
 
public:  // special members
  ObjectRef() = default;
  ~ObjectRef() override = default;
 
public:
  [[nodiscard]] bool valid() const noexcept { return ptr_.load() != nullptr; }

  [[nodiscard]] operator bool() const noexcept { return valid(); }  // NOLINT(hicpp-explicit-conversions)

  [[nodiscard]] T* operator->() noexcept { return ptr_.load(); }

  [[nodiscard]] const T* operator->() const noexcept { return ptr_.load(); }

  [[nodiscard]] T& get() noexcept { return *ptr_.load(); }

  [[nodiscard]] const T& get() const noexcept { return *ptr_.load(); }

  Callback onAdded(Callback&& function) noexcept { return std::exchange(onAdded_, std::move(function)); }

  Callback onRemoved(Callback&& function) noexcept { return std::exchange(onRemoved_, std::move(function)); }
 
protected:  // implements ObjectProviderListener
  void onObjectsAdded(const ObjectAdditionList& additions) override;
  void onObjectsRemoved(const ObjectRemovalList& removals) override;
 
private:
  [[nodiscard]] T* getCastedObject(Object* object);
 
private:
  std::atomic<T*> ptr_ = nullptr;
  Callback onAdded_ = nullptr;
  Callback onRemoved_ = nullptr;
};

 
//----------------------------------------------------------------------------------------------------------------------
// Inline implementation
//----------------------------------------------------------------------------------------------------------------------
 
template <typename T>
inline T* ObjectRef<T>::getCastedObject(Object* object)
{
  if constexpr (!std::is_same_v<T, Object>)
  {
    auto castedObject = dynamic_cast<T*>(object);
    if (!castedObject)
    {
      throwRuntimeError("invalid cast");
    }
    return castedObject;
  }
  else
  {
    return object;
  }
}
 
template <typename T>
inline void ObjectRef<T>::onObjectsAdded(const ObjectAdditionList& additions)
{
  for (const auto& addition: additions)
  {
    // only react to discovered instances
    auto* instance = getObjectInstance(addition);
    if (instance == nullptr)
    {
      continue;
    }
 
    // that are of our type
    if (auto* castedObject = getCastedObject(instance); castedObject)
    {
      ptr_.store(castedObject);
 
      if (onAdded_)
      {
        onAdded_();
      }
      return;
    }
  }
}
 
template <typename T>
inline void ObjectRef<T>::onObjectsRemoved(const ObjectRemovalList& removals)
{
  if (ptr_.load() != nullptr)
  {
    const auto* instance = ptr_.load()->asObject();
    for (const auto& removal: removals)
    {
      if (instance->getId() == removal.objectid)
      {
        ptr_.store(nullptr);
 
        if (onRemoved_)
        {
          onRemoved_();
        }
        return;
      }
    }
  }
}
 
}  // namespace sen
 
#endif  // SEN_CORE_OBJ_OBJECT_REF_H