subscription_traits.hpp

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// Copyright 2017 Open Source Robotics Foundation, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef RCLCPP__SUBSCRIPTION_TRAITS_HPP_
#define RCLCPP__SUBSCRIPTION_TRAITS_HPP_

#include <memory>

#include "rclcpp/function_traits.hpp"
#include "rcl/types.h"

namespace rclcpp
{

class QoS;

namespace subscription_traits
{

/*
 * The current version of uncrustify has a misinterpretion here
 * between `:` used for inheritance vs for initializer list
 * The result is that whenever a templated struct is used,
 * the colon has to be without any whitespace next to it whereas
 * when no template is used, the colon has to be separated by a space.
 * Cheers!
 */
template<typename T>
struct is_serialized_subscription_argument : std::false_type
{};

template<>
struct is_serialized_subscription_argument<rcl_serialized_message_t>: std::true_type
{};

template<>
struct is_serialized_subscription_argument<std::shared_ptr<rcl_serialized_message_t>>
  : std::true_type
{};

template<typename T>
struct is_serialized_subscription : is_serialized_subscription_argument<T>
{};

template<typename CallbackT>
struct is_serialized_callback
  : is_serialized_subscription_argument<
    typename rclcpp::function_traits::function_traits<CallbackT>::template argument_type<0>>
{};

template<typename MessageT>
struct extract_message_type
{
  using type = typename std::remove_cv<MessageT>::type;
};

template<typename MessageT>
struct extract_message_type<std::shared_ptr<MessageT>>: extract_message_type<MessageT>
{};

template<typename MessageT, typename Deleter>
struct extract_message_type<std::unique_ptr<MessageT, Deleter>>: extract_message_type<MessageT>
{};

template<
  typename CallbackT,
  // Do not attempt if CallbackT is an integer (mistaken for depth)
  typename = std::enable_if_t<!std::is_integral<
    std::remove_cv_t<std::remove_reference_t<CallbackT>>>::value>,
  // Do not attempt if CallbackT is a QoS (mistaken for qos)
  typename = std::enable_if_t<!std::is_base_of<
    rclcpp::QoS,
    std::remove_cv_t<std::remove_reference_t<CallbackT>>>::value>,
  // Do not attempt if CallbackT is a rmw_qos_profile_t (mistaken for qos profile)
  typename = std::enable_if_t<!std::is_same<
    rmw_qos_profile_t,
    std::remove_cv_t<std::remove_reference_t<CallbackT>>>::value>
>
struct has_message_type : extract_message_type<
    typename rclcpp::function_traits::function_traits<CallbackT>::template argument_type<0>>
{};

}  // namespace subscription_traits
}  // namespace rclcpp

#endif  // RCLCPP__SUBSCRIPTION_TRAITS_HPP_