cpp-scope-guard/include/scope_guard/scope_guard.hpp

//
//  scope_guard.hpp
//  memory
//
//  Created by Sam Jaffe on 9/24/15.
//
//

#pragma once

#include <functional>

class scope_exit {
public:
 template <typename F> scope_exit(F f) : on_exit_(f) {}
  
  scope_exit(scope_exit const &) = delete;
  scope_exit &operator=(scope_exit const &) = delete;
  scope_exit(scope_exit &&) = default;
  scope_exit &operator=(scope_exit &&) = default;
  
  ~scope_exit() noexcept { if (on_exit_) { on_exit_(); } }
  
  void release() { on_exit_ = {}; }

private:
  std::function<void()> on_exit_;
};

#if __cplusplus > 201402L
template <bool RunOnFailure>
class scope_exception {
public:
  template <typename F>
  scope_exception(F f) : on_exit_(f), depth_(std::uncaught_exceptions()) {}
  
  scope_exception(scope_exception const &) = delete;
  scope_exception &operator=(scope_exception const &) = delete;
  scope_exception(scope_exception &&) = default;
  scope_exception &operator=(scope_exception &&) = default;

  ~scope_exception() noexcept(RunOnFailure) {
    if (on_exit_ && RunOnFailure == is_failure()) { on_exit_(); }
  }
  
  void release() { on_exit_ = {}; }
  
private:
  bool is_failure() const {
    return std::uncaught_exceptions() > depth_;
  }
  
private:
  std::function<void()> on_exit_;
  int depth_;
};

using scope_failure = scope_exception<true>;
using scope_success = scope_exception<false>;
#endif

#if !defined(CONCAT)
#define CONCAT2(A, B) A##B
#define CONCAT(A, B) CONCAT2(A, B)
#endif

#define SCOPE_TYPE(t) CONCAT(scope_,t)
#define SCOPE_GUARD_NAME(t) CONCAT(CONCAT(scope_guard_,t),__LINE__)

#define scope(t) SCOPE_TYPE(t) SCOPE_GUARD_NAME(t) = [&]()
#define scope_guard(t, f) SCOPE_TYPE(t) SCOPE_GUARD_NAME(t){f};