66 lines
1.7 KiB
C++
66 lines
1.7 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#pragma once
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#include <utility>
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/**
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* Internal class. Do not use directly.
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*/
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template<typename F>
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class ScopeExitGuard {
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[[no_unique_address]]
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F function;
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bool enabled = true;
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public:
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explicit ScopeExitGuard(F &&f) noexcept
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:function(std::forward<F>(f)) {}
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ScopeExitGuard(ScopeExitGuard &&src) noexcept
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:function(std::move(src.function)),
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enabled(std::exchange(src.enabled, false)) {}
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/* destructors are "noexcept" by default; this explicit
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"noexcept" declaration allows the destructor to throw if
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the function can throw; without this, a throwing function
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would std::terminate() */
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~ScopeExitGuard() noexcept(noexcept(std::declval<F>()())) {
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if (enabled)
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function();
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}
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ScopeExitGuard(const ScopeExitGuard &) = delete;
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ScopeExitGuard &operator=(const ScopeExitGuard &) = delete;
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};
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/**
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* Internal class. Do not use directly.
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*/
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struct ScopeExitTag {
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/* this operator is a trick so we don't need to close
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parantheses at the end of the expression AtScopeExit()
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call */
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template<typename F>
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ScopeExitGuard<F> operator+(F &&f) noexcept {
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return ScopeExitGuard<F>(std::forward<F>(f));
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}
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};
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#define ScopeExitCat(a, b) a ## b
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#define ScopeExitName(line) ScopeExitCat(at_scope_exit_, line)
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/**
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* Call the block after this macro at the end of the current scope.
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* Parameters are lambda captures.
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*
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* This is exception-safe, however the given code block must not throw
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* exceptions.
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*
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* This attempts to be a better boost/scope_exit.hpp, without all of
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* Boost's compile-time and runtime bloat.
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*/
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#define AtScopeExit(...) auto ScopeExitName(__LINE__) = ScopeExitTag() + [__VA_ARGS__]()
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