functorPtr.h

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/*  This file is part of the OpenLB library
 *
 *  Copyright (C) 2017 Adrian Kummerlaender
 *  E-mail contact: info@openlb.net
 *  The most recent release of OpenLB can be downloaded at
 *  <http://www.openlb.net/>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2
 *  of the License, or (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA  02110-1301, USA.
*/
 
#ifndef FUNCTOR_PTR_H
#define FUNCTOR_PTR_H
 
#include <memory>
#include <type_traits>
 
namespace olb {
 
namespace util {
 
template<class F, class U = void>
struct has_identity_functor : std::false_type { };
template<class F>
struct has_identity_functor<F, std::void_t<typename F::identity_functor_type>> : std::true_type { };
 
}
 
 
template<typename F>
class FunctorPtr {
private:
  std::unique_ptr<F> _ownF;
  std::shared_ptr<F> _sharedF;
  F* _f;
  const bool _owning;
 
public:
  FunctorPtr(F& f);
  FunctorPtr(F* f);
 
  FunctorPtr(const std::unique_ptr<F>& f);
  FunctorPtr(std::unique_ptr<F>&& f);
  FunctorPtr(std::shared_ptr<F> f);
 
  FunctorPtr();
 
  FunctorPtr(FunctorPtr&) = delete;
  FunctorPtr(FunctorPtr&&) = default;
 
  template<typename... Args>
  bool operator()(Args... args)
  {
    return _f->operator()(std::forward<Args>(args)...);
  }
 
  typename std::add_lvalue_reference<F>::type operator*() const;
  typename std::add_pointer<F>::type operator->() const noexcept;
 
 
  operator bool() const;
 
 
  bool isOwning() const;
 
  template<typename G = F>
  auto toShared() -> typename std::enable_if< util::has_identity_functor<G>::value, std::shared_ptr<F>>::type;
  template<typename G = F>
  auto toShared() -> typename std::enable_if<!util::has_identity_functor<G>::value, std::shared_ptr<F>>::type;
 
};
 
}
 
#endif