scopeguard.h

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/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#pragma once
 
#include <utility>  // for std::move, std::forward
 
namespace android {
namespace base {
 
// ScopeGuard ensures that the specified functor is executed no matter how the
// current scope exits.
template <typename F>
class ScopeGuard {
 public:
  constexpr ScopeGuard(F&& f) : f_(std::forward<F>(f)), active_(true) {}
 
  constexpr ScopeGuard(ScopeGuard&& that) noexcept : f_(std::move(that.f_)), active_(that.active_) {
    that.active_ = false;
  }
 
  template <typename Functor>
  constexpr ScopeGuard(ScopeGuard<Functor>&& that) : f_(std::move(that.f_)), active_(that.active_) {
    that.active_ = false;
  }
 
  ~ScopeGuard() {
    if (active_) f_();
  }
 
  ScopeGuard() = delete;
  ScopeGuard(const ScopeGuard&) = delete;
  void operator=(const ScopeGuard&) = delete;
  void operator=(ScopeGuard&& that) = delete;
 
  void Disable() { active_ = false; }
 
  constexpr bool active() const { return active_; }
 
 private:
  template <typename Functor>
  friend class ScopeGuard;
 
  F f_;
  bool active_;
};
 
template <typename F>
ScopeGuard<F> make_scope_guard(F&& f) {
  return ScopeGuard<F>(std::forward<F>(f));
}
 
template<typename F>
ScopeGuard(F&& t) -> ScopeGuard<F>;
 
}  // namespace base
}  // namespace android