metaprogramming-impl.hpp

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namespace aikido {
namespace common {
 
//==============================================================================
template <class Pointee>
struct DynamicCastFactory_shared_ptr
{
  using type = std::shared_ptr<Pointee>;
 
  template <class Derived>
  static std::shared_ptr<Derived> cast(std::shared_ptr<Pointee> _pointer)
  {
    return std::dynamic_pointer_cast<Derived>(std::move(_pointer));
  }
};
 
//==============================================================================
template <class Pointee>
struct DynamicCastFactory_raw_ptr
{
  using type = Pointee*;
 
  template <class Derived>
  static Derived* cast(Pointee* _pointer)
  {
    return dynamic_cast<Derived*>(_pointer);
  }
};
 
//==============================================================================
template <
    template <class>
    class Factory,
    template <class>
    class Pointer,
    class BaseParameter>
struct DynamicCastFactory<Factory, Pointer, BaseParameter, common::type_list<>>
{
  template <class... Parameters>
  static std::nullptr_t create(
      typename Pointer<BaseParameter>::type /* unused */,
      Parameters&&... /* unused */)
  {
    return nullptr;
  }
};
 
//==============================================================================
template <
    template <class>
    class Factory,
    template <class>
    class Pointer,
    class BaseParameter,
    class Arg,
    class... Args>
struct DynamicCastFactory<
    Factory,
    Pointer,
    BaseParameter,
    common::type_list<Arg, Args...>>
{
  template <class... Parameters>
  static auto create(
      typename Pointer<BaseParameter>::type _base, Parameters&&... _params)
      -> decltype(Factory<Arg>::create(
          Pointer<BaseParameter>::template cast<Arg>(_base),
          std::forward<Parameters>(_params)...))
  {
    if (auto derived = Pointer<BaseParameter>::template cast<Arg>(_base))
    {
      return Factory<Arg>::create(
          std::move(derived), std::forward<Parameters>(_params)...);
    }
    else
    {
      return DynamicCastFactory<
          Factory,
          Pointer,
          BaseParameter,
          common::type_list<Args...>>::
          create(std::move(_base), std::forward<Parameters>(_params)...);
    }
  }
};
 
} // namespace common
} // namespace aikido