include/sdbusplus/slot.hpp

#pragma once

#include <systemd/sd-bus.h>

#include <memory>

namespace sdbusplus
{

namespace slot
{

using slotp_t = sd_bus_slot*;
struct slot;

namespace details
{

/** @brief unique_ptr functor to release a slot reference. */
struct SlotDeleter
{
    void operator()(slotp_t ptr) const
    {
        sd_bus_slot_unref(ptr);
    }
};

using slot = std::unique_ptr<sd_bus_slot, SlotDeleter>;

} // namespace details

/** @class slot
 *  @brief Provides C++ holder for sd_bus_slot instances.
 */
struct slot
{
    /* Define all of the basic class operations:
     *     Not allowed:
     *         - Default constructor to avoid nullptrs.
     *         - Copy operations due to internal unique_ptr.
     *     Allowed:
     *         - Move operations.
     *         - Destructor.
     */
    slot() = delete;
    slot(const slot&) = delete;
    slot& operator=(const slot&) = delete;
    slot(slot&&) = default;
    slot& operator=(slot&&) = default;
    ~slot() = default;

    /** @brief Conversion constructor for 'slotp_t'.
     *
     *  Takes ownership of the slot-pointer and releases it when done.
     */
    explicit slot(slotp_t s) : _slot(s)
    {}

    /** @brief Release ownership of the stored slot-pointer. */
    slotp_t release()
    {
        return _slot.release();
    }

    /** @brief Check if slot contains a real pointer. (non-nullptr). */
    explicit operator bool() const
    {
        return bool(_slot);
    }

  private:
    details::slot _slot;
};

} // namespace slot
} // namespace sdbusplus