ServiceProviderWrappers.h

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#ifndef LARCORE_COREUTILS_SERVICEPROVIDERWRAPPERS_H
#define LARCORE_COREUTILS_SERVICEPROVIDERWRAPPERS_H 1

// LArSoft libraries
#include "larcore/CoreUtils/ServiceUtil.h" // lar::providerFrom() (for includers)

// framework and support libraries
#include "art/Framework/Services/Registry/ServiceTable.h"

// C/C++ standard libraries
#include <memory> // std::unique_ptr<>

// forward declarations
namespace art {
  class ActivityRegistry;
}
namespace fhicl {
  class ParameterSet;
}

namespace lar {

  template <class PROVIDER>
  class SimpleServiceProviderWrapper {

  public:
    using provider_type = PROVIDER; 

    using Parameters = art::ServiceTable<typename provider_type::Config>;

    SimpleServiceProviderWrapper(Parameters const& config, art::ActivityRegistry&)
      : prov(std::make_unique<provider_type>(config()))
    {}

    provider_type const* provider() const { return prov.get(); }

  private:
    std::unique_ptr<provider_type> prov; 

  }; // SimpleServiceProviderWrapper<>

  template <class PROVIDER>
  class ServiceProviderInterfaceWrapper {

  public:
    using provider_type = PROVIDER; 

    virtual ~ServiceProviderInterfaceWrapper() = default;

    provider_type const* provider() const { return do_provider(); }

  protected:
    virtual provider_type const* do_provider() const = 0;

  }; // ServiceProviderInterfaceWrapper<>

  template <typename PROVIDER, typename INTERFACE>
  class ServiceProviderImplementationWrapper : public INTERFACE {

  public:
    using concrete_provider_type = PROVIDER;

    using service_interface_type = INTERFACE;

    using provider_type = typename service_interface_type::provider_type;

    using Parameters = art::ServiceTable<typename concrete_provider_type::Config>;

    ServiceProviderImplementationWrapper(Parameters const& config, art::ActivityRegistry&)
      : prov(std::make_unique<concrete_provider_type>(config()))
    {}

  private:
    std::unique_ptr<concrete_provider_type> prov; 

    virtual provider_type const* do_provider() const override { return prov.get(); }

  }; // ServiceProviderImplementationWrapper

} // namespace lar

#endif // LARCORE_COREUTILS_SERVICEPROVIDERWRAPPERS_H