85 lines
2.2 KiB
C++
85 lines
2.2 KiB
C++
// This file is part of the mcl project.
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// Copyright (c) 2022 merryhime
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// SPDX-License-Identifier: MIT
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#pragma once
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#include <exception>
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#include <type_traits>
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#include <utility>
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#include <mcl/macro/anonymous_variable.hpp>
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namespace mcl::detail {
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struct scope_exit_tag {};
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struct scope_fail_tag {};
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struct scope_success_tag {};
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template<typename Function>
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class scope_exit final {
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public:
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explicit scope_exit(Function&& fn)
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: function(std::move(fn)) {}
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~scope_exit() noexcept {
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function();
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}
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private:
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Function function;
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};
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template<typename Function>
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class scope_fail final {
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public:
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explicit scope_fail(Function&& fn)
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: function(std::move(fn)), exception_count(std::uncaught_exceptions()) {}
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~scope_fail() noexcept {
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if (std::uncaught_exceptions() > exception_count) {
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function();
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}
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}
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private:
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Function function;
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int exception_count;
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};
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template<typename Function>
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class scope_success final {
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public:
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explicit scope_success(Function&& fn)
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: function(std::move(fn)), exception_count(std::uncaught_exceptions()) {}
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~scope_success() {
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if (std::uncaught_exceptions() <= exception_count) {
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function();
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}
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}
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private:
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Function function;
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int exception_count;
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};
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// We use ->* here as it has the highest precedence of the operators we can use.
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template<typename Function>
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auto operator->*(scope_exit_tag, Function&& function) {
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return scope_exit<std::decay_t<Function>>{std::forward<Function>(function)};
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}
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template<typename Function>
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auto operator->*(scope_fail_tag, Function&& function) {
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return scope_fail<std::decay_t<Function>>{std::forward<Function>(function)};
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}
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template<typename Function>
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auto operator->*(scope_success_tag, Function&& function) {
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return scope_success<std::decay_t<Function>>{std::forward<Function>(function)};
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}
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} // namespace mcl::detail
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#define SCOPE_EXIT auto ANONYMOUS_VARIABLE(MCL_SCOPE_EXIT_VAR_) = ::mcl::detail::scope_exit_tag{}->*[&]() noexcept
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#define SCOPE_FAIL auto ANONYMOUS_VARIABLE(MCL_SCOPE_FAIL_VAR_) = ::mcl::detail::scope_fail_tag{}->*[&]() noexcept
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#define SCOPE_SUCCESS auto ANONYMOUS_VARIABLE(MCL_SCOPE_FAIL_VAR_) = ::mcl::detail::scope_success_tag{}->*[&]()
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