1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #pragma once 18 19 #include <utility> // for std::move, std::forward 20 21 namespace android { 22 namespace base { 23 24 // ScopeGuard ensures that the specified functor is executed no matter how the 25 // current scope exits. 26 template <typename F> 27 class ScopeGuard { 28 public: ScopeGuard(F f)29 constexpr ScopeGuard(F f) : f_(std::move(f)), active_(true) {} 30 ScopeGuard(ScopeGuard && that)31 constexpr ScopeGuard(ScopeGuard&& that) noexcept : f_(std::move(that.f_)), active_(that.active_) { 32 that.active_ = false; 33 } 34 35 template <typename Functor> ScopeGuard(ScopeGuard<Functor> && that)36 constexpr ScopeGuard(ScopeGuard<Functor>&& that) noexcept 37 : f_(std::move(that.f_)), active_(that.active_) { 38 that.active_ = false; 39 } 40 noexcept(noexcept (f_ ()))41 ~ScopeGuard() noexcept(noexcept(f_())) { 42 if (active_) f_(); 43 } 44 45 ScopeGuard() = delete; 46 ScopeGuard(const ScopeGuard&) = delete; 47 void operator=(const ScopeGuard&) = delete; 48 void operator=(ScopeGuard&& that) = delete; 49 Disable()50 void Disable() noexcept { active_ = false; } 51 active()52 constexpr bool active() const noexcept { return active_; } 53 54 private: 55 template <typename Functor> 56 friend class ScopeGuard; 57 58 F f_; 59 bool active_; 60 }; 61 62 template <typename F> make_scope_guard(F && f)63auto make_scope_guard(F&& f) { 64 return ScopeGuard<std::remove_reference_t<F>>(std::forward<F>(f)); 65 } 66 67 } // namespace base 68 } // namespace android 69