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+// Copyright 2021 The Abseil Authors.
+//
+// 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
+//
+// https://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.
+//
+// -----------------------------------------------------------------------------
+// File: cleanup.h
+// -----------------------------------------------------------------------------
+//
+// `absl::Cleanup` implements the scope guard idiom, invoking `operator()() &&`
+// on the callback it was constructed with, on scope exit.
+//
+// Example:
+//
+// ```
+// void CopyGoodData(const char* input_path, const char* output_path) {
+// FILE* in_file = fopen(input_path, "r");
+// FILE* out_file = fopen(output_path, "w");
+// if (in_file == nullptr || out_file == nullptr) return;
+//
+// // C++17 style using class template argument deduction
+// absl::Cleanup in_closer = [&in_file] { fclose(in_file); };
+//
+// // C++11 style using the factory function
+// auto out_closer = absl::MakeCleanup([&out_file] { fclose(out_file); });
+//
+// // `fclose` will be called on all exit paths by the cleanup instances
+//
+// Data data;
+// while (ReadData(in_file, &data)) {
+// if (data.IsBad()) {
+// LOG(ERROR) << "Found bad data.";
+// return; // `in_closer` and `out_closer` will call their callbacks
+// }
+// SaveData(out_file, &data);
+// }
+// return; // `in_closer` and `out_closer` will call their callbacks
+// }
+// ```
+//
+// `std::move(cleanup).Invoke()` will execute the callback early, before
+// destruction, and prevent the callback from executing in the destructor.
+//
+// Alternatively, `std::move(cleanup).Cancel()` will prevent the callback from
+// ever executing at all.
+//
+// Once a cleanup object has been `std::move(...)`-ed, it may not be used again.
+
+#ifndef ABSL_CLEANUP_CLEANUP_H_
+#define ABSL_CLEANUP_CLEANUP_H_
+
+#include <utility>
+
+#include "absl/base/config.h"
+#include "absl/base/macros.h"
+#include "absl/cleanup/internal/cleanup.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+template <typename Arg, typename Callback = void()>
+class ABSL_MUST_USE_RESULT Cleanup {
+ static_assert(cleanup_internal::WasDeduced<Arg>(),
+ "Explicit template parameters are not supported.");
+
+ static_assert(cleanup_internal::ReturnsVoid<Callback>(),
+ "Callbacks that return values are not supported.");
+
+ public:
+ Cleanup(Callback callback) : storage_(std::move(callback)) {} // NOLINT
+
+ Cleanup(Cleanup&& other) : storage_(std::move(other.storage_)) {}
+
+ void Cancel() && {
+ ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
+ storage_.DisengageCallback();
+ }
+
+ void Invoke() && {
+ ABSL_HARDENING_ASSERT(storage_.IsCallbackEngaged());
+ storage_.DisengageCallback();
+ storage_.InvokeCallback();
+ }
+
+ ~Cleanup() {
+ if (storage_.IsCallbackEngaged()) {
+ storage_.InvokeCallback();
+ }
+ }
+
+ private:
+ cleanup_internal::Storage<Callback> storage_;
+};
+
+// `auto c = absl::MakeCleanup(/* callback */);`
+//
+// C++11 type deduction API for creating an instance of `absl::Cleanup`.
+template <typename... Args, typename Callback>
+absl::Cleanup<cleanup_internal::Tag, Callback> MakeCleanup(Callback callback) {
+ static_assert(cleanup_internal::WasDeduced<cleanup_internal::Tag, Args...>(),
+ "Explicit template parameters are not supported.");
+
+ static_assert(cleanup_internal::ReturnsVoid<Callback>(),
+ "Callbacks that return values are not supported.");
+
+ return {std::move(callback)};
+}
+
+// `absl::Cleanup c = /* callback */;`
+//
+// C++17 type deduction API for creating an instance of `absl::Cleanup`.
+#if defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+template <typename Callback>
+Cleanup(Callback callback) -> Cleanup<cleanup_internal::Tag, Callback>;
+#endif // defined(ABSL_HAVE_CLASS_TEMPLATE_ARGUMENT_DEDUCTION)
+
+ABSL_NAMESPACE_END
+} // namespace absl
+
+#endif // ABSL_CLEANUP_CLEANUP_H_