93 lines
2.6 KiB
C++
93 lines
2.6 KiB
C++
// Copyright 2019 The Marl Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Finally can be used to execute a lambda or function when the final reference
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// to the Finally is dropped.
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//
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// The purpose of a finally is to perform cleanup or termination logic and is
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// especially useful when there are multiple early returns within a function.
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//
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// A moveable Finally can be constructed with marl::make_finally().
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// A sharable Finally can be constructed with marl::make_shared_finally().
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#ifndef marl_finally_h
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#define marl_finally_h
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#include "export.h"
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#include <functional>
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#include <memory>
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#include <utility>
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namespace marl {
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// Finally is a pure virtual base class, implemented by the templated
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// FinallyImpl.
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class Finally {
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public:
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virtual ~Finally() = default;
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};
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// FinallyImpl implements a Finally.
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// The template parameter F is the function type to be called when the finally
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// is destructed. F must have the signature void().
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template <typename F>
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class FinallyImpl : public Finally {
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public:
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MARL_NO_EXPORT inline FinallyImpl(const F& func);
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MARL_NO_EXPORT inline FinallyImpl(F&& func);
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MARL_NO_EXPORT inline FinallyImpl(FinallyImpl<F>&& other);
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MARL_NO_EXPORT inline ~FinallyImpl();
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private:
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FinallyImpl(const FinallyImpl<F>& other) = delete;
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FinallyImpl<F>& operator=(const FinallyImpl<F>& other) = delete;
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FinallyImpl<F>& operator=(FinallyImpl<F>&&) = delete;
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F func;
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bool valid = true;
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};
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template <typename F>
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FinallyImpl<F>::FinallyImpl(const F& func_) : func(func_) {}
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template <typename F>
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FinallyImpl<F>::FinallyImpl(F&& func_) : func(std::move(func_)) {}
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template <typename F>
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FinallyImpl<F>::FinallyImpl(FinallyImpl<F>&& other)
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: func(std::move(other.func)) {
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other.valid = false;
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}
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template <typename F>
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FinallyImpl<F>::~FinallyImpl() {
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if (valid) {
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func();
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}
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}
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template <typename F>
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inline FinallyImpl<F> make_finally(F&& f) {
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return FinallyImpl<F>(std::forward<F>(f));
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}
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template <typename F>
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inline std::shared_ptr<Finally> make_shared_finally(F&& f) {
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return std::make_shared<FinallyImpl<F>>(std::forward<F>(f));
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}
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} // namespace marl
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#endif // marl_finally_h
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