114 lines
3.6 KiB
C++
114 lines
3.6 KiB
C++
// *****************************************************************************
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// * This file is part of the FreeFileSync project. It is distributed under *
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// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0 *
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// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
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// *****************************************************************************
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#ifndef SCOPE_GUARD_H_8971632487321434
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#define SCOPE_GUARD_H_8971632487321434
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#include <cassert>
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#include "legacy_compiler.h" //std::uncaught_exceptions
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//best of Zen, Loki and C++17
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namespace zen
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{
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/* Scope Guard
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auto guardAio = zen::makeGuard<ScopeGuardRunMode::onExit>([&] { ::CloseHandle(hDir); });
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...
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guardAio.dismiss();
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Scope Exit:
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ZEN_ON_SCOPE_EXIT (CleanUp());
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ZEN_ON_SCOPE_FAIL (UndoTemporaryWork());
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ZEN_ON_SCOPE_SUCCESS(NotifySuccess()); */
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enum class ScopeGuardRunMode
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{
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onExit,
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onSuccess,
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onFail
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};
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//partially specialize scope guard destructor code and get rid of those pesky MSVC "4127 conditional expression is constant"
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template <typename F> inline
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void runScopeGuardDestructor(F& fun, bool failed, std::integral_constant<ScopeGuardRunMode, ScopeGuardRunMode::onExit>)
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{
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if (!failed)
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fun(); //throw X
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else
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try { fun(); }
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catch (...) { assert(false); }
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}
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template <typename F> inline
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void runScopeGuardDestructor(F& fun, bool failed, std::integral_constant<ScopeGuardRunMode, ScopeGuardRunMode::onSuccess>)
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{
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if (!failed)
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fun(); //throw X
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}
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template <typename F> inline
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void runScopeGuardDestructor(F& fun, bool failed, std::integral_constant<ScopeGuardRunMode, ScopeGuardRunMode::onFail>) noexcept
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{
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if (failed)
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try { fun(); }
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catch (...) { assert(false); }
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}
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template <ScopeGuardRunMode runMode, typename F>
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class ScopeGuard
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{
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public:
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explicit ScopeGuard(const F& fun) : fun_(fun) {}
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explicit ScopeGuard( F&& fun) : fun_(std::move(fun)) {}
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//ScopeGuard(ScopeGuard&& tmp) :
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// fun_(std::move(tmp.fun_)),
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// exeptionCount_(tmp.exeptionCount_),
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// dismissed_(tmp.dismissed_) { tmp.dismissed_ = true; }
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~ScopeGuard() noexcept(runMode == ScopeGuardRunMode::onFail)
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{
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if (!dismissed_)
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{
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const bool failed = std::uncaught_exceptions() > exeptionCount_;
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runScopeGuardDestructor(fun_, failed, std::integral_constant<ScopeGuardRunMode, runMode>());
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}
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}
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void dismiss() { dismissed_ = true; }
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private:
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ScopeGuard (const ScopeGuard&) = delete;
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ScopeGuard& operator=(const ScopeGuard&) = delete;
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const F fun_;
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const int exeptionCount_ = std::uncaught_exceptions();
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bool dismissed_ = false;
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};
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template <ScopeGuardRunMode runMode, class F> inline
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auto makeGuard(F&& fun) { return ScopeGuard<runMode, std::decay_t<F>>(std::forward<F>(fun)); }
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}
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#define ZEN_CONCAT_SUB(X, Y) X ## Y
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#define ZEN_CONCAT(X, Y) ZEN_CONCAT_SUB(X, Y)
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#define ZEN_CHECK_CASE_FOR_CONSTANT(X) case X: return ZEN_CHECK_CASE_FOR_CONSTANT_IMPL(#X)
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#define ZEN_CHECK_CASE_FOR_CONSTANT_IMPL(X) L ## X
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#define ZEN_ON_SCOPE_EXIT(X) [[maybe_unused]] auto ZEN_CONCAT(scopeGuard, __LINE__) = zen::makeGuard<zen::ScopeGuardRunMode::onExit >([&]{ X; });
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#define ZEN_ON_SCOPE_FAIL(X) [[maybe_unused]] auto ZEN_CONCAT(scopeGuard, __LINE__) = zen::makeGuard<zen::ScopeGuardRunMode::onFail >([&]{ X; });
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#define ZEN_ON_SCOPE_SUCCESS(X) [[maybe_unused]] auto ZEN_CONCAT(scopeGuard, __LINE__) = zen::makeGuard<zen::ScopeGuardRunMode::onSuccess>([&]{ X; });
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#endif //SCOPE_GUARD_H_8971632487321434
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