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// Copyright 2019 The Marl 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.
// Finally can be used to execute a lambda or function when the final reference
// to the Finally is dropped.
//
// The purpose of a finally is to perform cleanup or termination logic and is
// especially useful when there are multiple early returns within a function.
//
// A moveable Finally can be constructed with marl::make_finally().
// A sharable Finally can be constructed with marl::make_shared_finally().
#ifndef marl_finally_h
#define marl_finally_h
#include "export.h"
#include <functional>
#include <memory>
#include <utility>
namespace marl {
// Finally is a pure virtual base class, implemented by the templated
// FinallyImpl.
class Finally {
public:
virtual ~Finally() = default;
};
// FinallyImpl implements a Finally.
// The template parameter F is the function type to be called when the finally
// is destructed. F must have the signature void().
template <typename F>
class FinallyImpl : public Finally {
public:
MARL_NO_EXPORT inline FinallyImpl(const F& func);
MARL_NO_EXPORT inline FinallyImpl(F&& func);
MARL_NO_EXPORT inline FinallyImpl(FinallyImpl<F>&& other);
MARL_NO_EXPORT inline ~FinallyImpl();
private:
FinallyImpl(const FinallyImpl<F>& other) = delete;
FinallyImpl<F>& operator=(const FinallyImpl<F>& other) = delete;
FinallyImpl<F>& operator=(FinallyImpl<F>&&) = delete;
F func;
bool valid = true;
};
template <typename F>
FinallyImpl<F>::FinallyImpl(const F& func_) : func(func_) {}
template <typename F>
FinallyImpl<F>::FinallyImpl(F&& func_) : func(std::move(func_)) {}
template <typename F>
FinallyImpl<F>::FinallyImpl(FinallyImpl<F>&& other)
: func(std::move(other.func)) {
other.valid = false;
}
template <typename F>
FinallyImpl<F>::~FinallyImpl() {
if (valid) {
func();
}
}
template <typename F>
inline FinallyImpl<F> make_finally(F&& f) {
return FinallyImpl<F>(std::forward<F>(f));
}
template <typename F>
inline std::shared_ptr<Finally> make_shared_finally(F&& f) {
return std::make_shared<FinallyImpl<F>>(std::forward<F>(f));
}
} // namespace marl
#endif // marl_finally_h