.. _program_listing_file_include_rclcpp_subscription_traits.hpp:

Program Listing for File subscription_traits.hpp
================================================

|exhale_lsh| :ref:`Return to documentation for file <file_include_rclcpp_subscription_traits.hpp>` (``include/rclcpp/subscription_traits.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   // 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 "rclcpp/serialized_message.hpp"
   #include "rclcpp/subscription_options.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<SerializedMessage>: std::true_type
   {};
   
   template<>
   struct is_serialized_subscription_argument<std::shared_ptr<SerializedMessage>>
     : 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_t<std::remove_reference_t<MessageT>>;
   };
   
   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,
     typename AllocatorT = std::allocator<void>,
     // 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>,
     // Do not attempt if CallbackT is a rclcpp::SubscriptionOptionsWithAllocator
     typename = std::enable_if_t<!std::is_same<
       rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>,
       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_