Class callable_vtable

include/concurrencpp/task.h:43–176

    template<class callable_type>
    class callable_vtable {

       private:
        static callable_type* inline_ptr(void* src) noexcept {
            return static_cast<callable_type*>(src);
        }

        static callable_type* allocated_ptr(void* src) noexcept {
            return *static_cast<callable_type**>(src);
        }

        static callable_type*& allocated_ref_ptr(void* src) noexcept {
            return *static_cast<callable_type**>(src);
        }

        static void move_destroy_inline(void* src, void* dst) noexcept {
            auto callable_ptr = inline_ptr(src);
            new (dst) callable_type(std::move(*callable_ptr));
            callable_ptr->~callable_type();
        }

        static void move_destroy_allocated(void* src, void* dst) noexcept {
            auto callable_ptr = std::exchange(allocated_ref_ptr(src), nullptr);
            new (dst) callable_type*(callable_ptr);
        }

        static void execute_destroy_inline(void* target) {
            auto callable_ptr = inline_ptr(target);
            (*callable_ptr)();
            callable_ptr->~callable_type();
        }

        static void execute_destroy_allocated(void* target) {
            auto callable_ptr = allocated_ptr(target);
            (*callable_ptr)();
            delete callable_ptr;
        }

        static void destroy_inline(void* target) noexcept {
            auto callable_ptr = inline_ptr(target);
            callable_ptr->~callable_type();
        }

        static void destroy_allocated(void* target) noexcept {
            auto callable_ptr = allocated_ptr(target);
            delete callable_ptr;
        }

        static constexpr vtable make_vtable() noexcept {
            void (*move_destroy_fn)(void* src, void* dst) noexcept = nullptr;
            void (*destroy_fn)(void* target) noexcept = nullptr;

            if constexpr (std::is_trivially_copy_constructible_v<callable_type> && std::is_trivially_destructible_v<callable_type> &&
                          is_inlinable()) {
                move_destroy_fn = nullptr;
            } else {
                move_destroy_fn = move_destroy;
            }