scope_exit.h

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#pragma once
 
#include <concepts>
#include <type_traits>
#include <utility>
 
namespace osc
{
    template<std::invocable EF>
    class [[nodiscard]] ScopeExit final {
    public:
        template<typename Fn>
        requires (
            std::destructible<EF> and
            std::is_constructible_v<EF, Fn> and
            not std::same_as<std::remove_cvref_t<Fn>, ScopeExit>
        )
        explicit ScopeExit(Fn&& fn) : exit_function_{std::forward<Fn>(fn)} {}
 
        ScopeExit(const ScopeExit&) = delete;
 
        ScopeExit(ScopeExit&& tmp) noexcept
        requires (std::is_nothrow_move_constructible_v<EF>) :
            exit_function_{std::move(tmp.exit_function_)},
            is_active_{std::exchange(tmp.is_active_, false)}
        {}
 
        ScopeExit(ScopeExit&& tmp) noexcept(std::is_nothrow_copy_constructible_v<EF>)
        requires (not std::is_nothrow_move_constructible_v<EF> and std::is_copy_constructible_v<EF>) :
            exit_function_{tmp.exit_function_},  // NOLINT(performance-move-constructor-init)
            is_active_{std::exchange(tmp.is_active_, false)}
        {}
 
        ScopeExit& operator=(const ScopeExit&) = delete;
        ScopeExit& operator=(ScopeExit&&) noexcept = delete;
 
        ~ScopeExit() noexcept
        {
            if (is_active_) {
                exit_function_();
            }
        }
 
        void release() noexcept { is_active_ = false; }
 
        private:
            EF exit_function_;
            bool is_active_ = true;
    };
 
    template<typename EF>
    ScopeExit(EF) -> ScopeExit<EF>;
}