scope.hpp

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#pragma once
 
#include <functional>  // invoke
#include <type_traits>
#include <utility>  // move
 
namespace opcua::detail {
 
/**
 * General-purpose scope guard intended to call its exit function when a scope is exited.
 * @see https://en.cppreference.com/w/cpp/experimental/scope_exit
 */
template <typename Fn>
class [[nodiscard]] ScopeExit {
public:
    static_assert(std::is_nothrow_move_constructible_v<Fn>);
    static_assert(std::is_invocable_v<Fn>);
 
    explicit ScopeExit(Fn&& fn) noexcept
        : fn_{std::move(fn)} {}
 
    ScopeExit(ScopeExit&& other) noexcept
        : fn_{std::move(other.fn_)},
          active_{other.active_} {
        other.release();
    }
 
    ~ScopeExit() noexcept(std::is_nothrow_invocable_v<Fn>) {
        if (active_) {
            std::invoke(fn_);
        }
    }
 
    ScopeExit(const ScopeExit&) = delete;
    ScopeExit& operator=(const ScopeExit&) = delete;
    ScopeExit& operator=(ScopeExit&&) = delete;
 
    void release() noexcept {
        active_ = false;
    }
 
private:
    Fn fn_;
    bool active_{true};
};
 
}  // namespace opcua::detail