Mini Shell

/*
   Copyright (c) 2020, MariaDB

   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; version 2 of
   the License.

   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 St, Fifth Floor, Boston, MA 02110-1335  USA
*/

#pragma once

#include <type_traits>
#include <utility>

namespace detail
{

template <typename Callable> class scope_exit
{
public:
  template <typename F>
  explicit scope_exit(F &&f) : function_(std::forward<F>(f))
  {
  }

  scope_exit(scope_exit &&rhs)
      : function_(std::move(rhs.function_)), engaged_(rhs.engaged_)
  {
    rhs.release();
  }

  scope_exit(const scope_exit &)= delete;
  scope_exit &operator=(scope_exit &&)= delete;
  scope_exit &operator=(const scope_exit &)= delete;

  void release() { engaged_= false; }

  ~scope_exit()
  {
    if (engaged_)
      function_();
  }

private:
  Callable function_;
  bool engaged_= true;
};

} // end namespace detail

template <typename Callable>
detail::scope_exit<typename std::decay<Callable>::type>
make_scope_exit(Callable &&f)
{
  return detail::scope_exit<typename std::decay<Callable>::type>(
      std::forward<Callable>(f));
}

#define CONCAT_IMPL(x, y) x##y

#define CONCAT(x, y) CONCAT_IMPL(x, y)

#define ANONYMOUS_VARIABLE CONCAT(_anonymous_variable, __LINE__)

#define SCOPE_EXIT auto ANONYMOUS_VARIABLE= make_scope_exit