Factory.hpp

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#ifndef DART_COMMON_FACTORY_HPP_
#define DART_COMMON_FACTORY_HPP_
 
#include <functional>
#include <memory>
#include <unordered_map>
#include <unordered_set>
 
#include "dart/common/Singleton.hpp"
#include "dart/common/StlHelpers.hpp"
 
namespace dart {
namespace common {
 
template <
    typename KeyT,
    typename BaseT,
    typename HeldT = std::shared_ptr<BaseT>,
    typename... Args>
class Factory
{
public:
  struct EnumClassHash;
 
  using This = Factory<KeyT, BaseT, HeldT>;
  using Creator = std::function<HeldT(Args...)>;
  template <typename Key>
  using HashType = typename std::conditional<
      std::is_enum<Key>::value,
      EnumClassHash,
      std::hash<Key>>::type;
  using CreatorMap = std::unordered_map<KeyT, Creator, HashType<KeyT>>;
 
  Factory() = default;
 
  virtual ~Factory() = default;
 
  void registerCreator(const KeyT& key, Creator creator);
 
  template <typename Derived>
  void registerCreator(const KeyT& key);
 
  void unregisterCreator(const KeyT& key);
 
  void unregisterAllCreators();
 
  bool canCreate(const KeyT& key);
 
  HeldT create(const KeyT& key, Args&&... args);
  // TODO(JS): Add create() for creating smart_pointers
  // (see: https://github.com/dartsim/dart/pull/845)
 
  std::unordered_set<KeyT> getKeys() const;
 
private:
  template <typename Derived>
  static HeldT defaultCreator(Args&&... args);
 
  CreatorMap mCreatorMap;
};
 
template <
    typename KeyT,
    typename BaseT,
    typename DerivedT,
    typename HeldT = std::shared_ptr<BaseT>,
    typename... Args>
class FactoryRegistrar final
{
public:
  using This = FactoryRegistrar<KeyT, BaseT, DerivedT, HeldT>;
  using FactoryType = Factory<KeyT, BaseT, HeldT, Args...>;
  using SingletonFactory = Singleton<FactoryType>;
  using Creator = typename FactoryType::Creator;
 
  FactoryRegistrar(const KeyT& key, Creator creator);
 
  explicit FactoryRegistrar(const KeyT& key);
};
 
} // namespace common
} // namespace dart
 
#include "dart/common/detail/Factory-impl.hpp"
 
#endif // DART_COMMON_FACTORY_HPP_