clone_ptr.h

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#ifndef FWCore_Utilities_clone_ptr_h
#define FWCore_Utilities_clone_ptr_h

#include <memory>

namespace extstd {

  /* modify unique_ptr behaviour adding a "cloning" copy-constructor and assignment-operator
   */
  template <typename T>
  struct clone_ptr : public std::unique_ptr<T> {
    template <typename... Args>
    explicit clone_ptr(Args&&... args) noexcept : std::unique_ptr<T>(std::forward<Args>(args)...) {}

    clone_ptr(clone_ptr const& rh) : std::unique_ptr<T>(rh ? rh->clone() : nullptr) {}
    clone_ptr(clone_ptr&& rh) noexcept : std::unique_ptr<T>(std::move(rh)) {}

    clone_ptr& operator=(clone_ptr const& rh) {
      if (&rh != this)
        this->reset(rh ? rh->clone() : nullptr);
      return *this;
    }
    clone_ptr& operator=(clone_ptr&& rh) noexcept {
      if (&rh != this)
        std::unique_ptr<T>::operator=(std::move(rh));
      return *this;
    }

    template <typename U>
    clone_ptr(clone_ptr<U> const& rh) : std::unique_ptr<T>(rh ? rh->clone() : nullptr) {}
    template <typename U>
    clone_ptr(clone_ptr<U>&& rh) noexcept : std::unique_ptr<T>(std::move(rh)) {}

    template <typename U>
    clone_ptr& operator=(clone_ptr<U> const& rh) {
      if (&rh != this)
        this->reset(rh ? rh->clone() : nullptr);
      return *this;
    }
    template <typename U>
    clone_ptr& operator=(clone_ptr<U>&& rh) noexcept {
      if (&rh != this)
        std::unique_ptr<T>::operator=(std::move(rh));
      return *this;
    }
  };

}  // namespace extstd

#endif