ostream_handle_impl.h

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#ifndef cetlib_detail_ostream_handle_impl_h
#define cetlib_detail_ostream_handle_impl_h

#include <fstream>
#include <ostream>
#include <string>

namespace cet::detail {

  // Interface
  class ostream_handle_base {
  public:
    virtual ~ostream_handle_base() = default;
    std::ostream&
    stream()
    {
      return get_stream();
    }

  private:
    virtual std::ostream& get_stream() = 0;
  };

  // Concrete types below
  class ostream_observer : public ostream_handle_base {
  public:
    ostream_observer(std::ostream& os) : os_{os} {}

  private:
    std::ostream& os_;
    std::ostream&
    get_stream() override
    {
      return os_;
    }
  };

  template <typename OSTREAM,
            typename =
              std::enable_if_t<std::is_base_of_v<std::ostream, OSTREAM>>>
  class ostream_owner : public ostream_handle_base {
  public:
    ostream_owner(OSTREAM&& os) : os_(std::move(os)) {}

  private:
    OSTREAM os_;
    std::ostream&
    get_stream() override
    {
      return os_;
    }
  };
}

#endif /* cetlib_detail_ostream_handle_impl_h */

// Local variables:
// mode: c++
// End: