Factory-impl.hpp

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#ifndef DART_COMMON_DETAIL_FACTORY_IMPL_HPP_
#define DART_COMMON_DETAIL_FACTORY_IMPL_HPP_
 
#include "dart/common/Console.hpp"
#include "dart/common/Factory.hpp"
#include "dart/common/Memory.hpp"
 
namespace dart {
namespace common {
 
namespace detail {
 
//==============================================================================
template <typename T, typename HeldT, typename... Args>
struct DefaultCreator
{
  static HeldT run(Args&&... args)
  {
    return HeldT(new T(std::forward<Args>(args)...));
  }
};
 
//==============================================================================
template <typename T, typename... Args>
struct DefaultCreator<T, std::unique_ptr<T>, Args...>
{
  static std::unique_ptr<T> run(Args&&... args)
  {
    return std::make_unique<T>(std::forward<Args>(args)...);
  }
};
 
//==============================================================================
template <typename T, typename... Args>
struct DefaultCreator<T, std::shared_ptr<T>, Args...>
{
  static std::shared_ptr<T> run(Args&&... args)
  {
    return std::make_shared<T>(std::forward<Args>(args)...);
  }
};
 
} // namespace detail
 
//==============================================================================
// std::hash doesn't support enum type. This is an workaround for it.
// Reference: http://stackoverflow.com/a/24847480
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
struct Factory<KeyT, BaseT, HeldT, Args...>::EnumClassHash
{
  template <typename T>
  std::size_t operator()(T t) const
  {
    return static_cast<std::size_t>(t);
  }
};
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
void Factory<KeyT, BaseT, HeldT, Args...>::registerCreator(
    const KeyT& key, Creator creator)
{
  mCreatorMap[key] = std::move(creator);
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
template <typename Derived>
void Factory<KeyT, BaseT, HeldT, Args...>::registerCreator(const KeyT& key)
{
  return registerCreator(key, &Factory::defaultCreator<Derived>);
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
void Factory<KeyT, BaseT, HeldT, Args...>::unregisterCreator(const KeyT& key)
{
  mCreatorMap.erase(key);
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
void Factory<KeyT, BaseT, HeldT, Args...>::unregisterAllCreators()
{
  mCreatorMap.clear();
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
bool Factory<KeyT, BaseT, HeldT, Args...>::canCreate(const KeyT& key)
{
  const auto it = mCreatorMap.find(key);
 
  return (it != mCreatorMap.end());
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
HeldT Factory<KeyT, BaseT, HeldT, Args...>::create(
    const KeyT& key, Args&&... args)
{
  const auto it = mCreatorMap.find(key);
 
  const auto found = (it != mCreatorMap.end());
  if (!found)
  {
    dtwarn << "[Factory] Failed to create an object of '"
           << typeid(BaseT).name() << "' class with the key (type: '"
           << typeid(KeyT).name() << "'). Returning nullptr instead.\n";
    // TODO(JS): Print the key if the << operator is defined.
 
    return nullptr;
  }
 
  return it->second(std::forward<Args>(args)...);
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
std::unordered_set<KeyT> Factory<KeyT, BaseT, HeldT, Args...>::getKeys() const
{
  std::unordered_set<KeyT> keys;
  for (const auto& entry : mCreatorMap)
    keys.insert(entry.first);
 
  return keys;
}
 
//==============================================================================
template <typename KeyT, typename BaseT, typename HeldT, typename... Args>
template <typename Derived>
HeldT Factory<KeyT, BaseT, HeldT, Args...>::defaultCreator(Args&&... args)
{
  return detail::DefaultCreator<Derived, HeldT, Args...>::run(
      std::forward<Args>(args)...);
}
 
//==============================================================================
template <
    typename KeyT,
    typename BaseT,
    typename DerivedT,
    typename HeldT,
    typename... Args>
FactoryRegistrar<KeyT, BaseT, DerivedT, HeldT, Args...>::FactoryRegistrar(
    const KeyT& key, Creator creator)
{
  SingletonFactory::getSingleton().registerCreator(key, creator);
}
 
//==============================================================================
template <
    typename KeyT,
    typename BaseT,
    typename DerivedT,
    typename HeldT,
    typename... Args>
FactoryRegistrar<KeyT, BaseT, DerivedT, HeldT, Args...>::FactoryRegistrar(
    const KeyT& key)
{
  SingletonFactory::getSingleton().template registerCreator<DerivedT>(key);
}
 
} // namespace common
} // namespace dart
 
#endif // DART_COMMON_DETAIL_FACTORY_IMPL_HPP_