Function GetFreeUnitNumber

src/vehicle.cpp:1876–1892

* Get an unused unit number for a vehicle (if allowed). * @param type Type of vehicle * @return A unused unit number for the given type of vehicle if it is allowed to build one, else \c UINT16_MAX. */

 * @return A unused unit number for the given type of vehicle if it is allowed to build one, else \c UINT16_MAX.
 */
UnitID GetFreeUnitNumber(VehicleType type)
{
	/* Check whether it is allowed to build another vehicle. */
	uint max_veh;
	switch (type) {
		case VEH_TRAIN:    max_veh = _settings_game.vehicle.max_trains;   break;
		case VEH_ROAD:     max_veh = _settings_game.vehicle.max_roadveh;  break;
		case VEH_SHIP:     max_veh = _settings_game.vehicle.max_ships;    break;
		case VEH_AIRCRAFT: max_veh = _settings_game.vehicle.max_aircraft; break;
		default: NOT_REACHED();
	}

	const Company *c = Company::Get(_current_company);
	if (c->group_all[type].num_vehicle >= max_veh) return UINT16_MAX; // Currently already at the limit, no room to make a new one.

	return c->freeunits[type].NextID();
}


/**