.. _program_listing_file_include_rclcpp_type_adapter.hpp:

Program Listing for File type_adapter.hpp
=========================================

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

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

.. code-block:: cpp

   // Copyright 2021 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__TYPE_ADAPTER_HPP_
   #define RCLCPP__TYPE_ADAPTER_HPP_
   
   #include <type_traits>
   
   namespace rclcpp
   {
   
   
   template<typename CustomType, typename ROSMessageType = void, class Enable = void>
   struct TypeAdapter
   {
     using is_specialized = std::false_type;
     using custom_type = CustomType;
     // In this case, the CustomType is the only thing given, or there is no specialization.
     // Assign ros_message_type to CustomType for the former case.
     using ros_message_type = CustomType;
   };
   
   template<typename T>
   struct is_type_adapter : std::false_type {};
   
   template<typename ... Ts>
   struct is_type_adapter<TypeAdapter<Ts...>>: std::true_type {};
   
   template<typename T>
   struct TypeAdapter<T, void, std::enable_if_t<is_type_adapter<T>::value>>: T {};
   
   namespace detail
   {
   
   template<typename CustomType, typename ROSMessageType>
   struct assert_type_pair_is_specialized_type_adapter
   {
     using type_adapter = TypeAdapter<CustomType, ROSMessageType>;
     static_assert(
       type_adapter::is_specialized::value,
       "No type adapter for this custom type/ros message type pair");
   };
   
   }  // namespace detail
   
   template<typename CustomType>
   struct adapt_type
   {
     template<typename ROSMessageType>
     using as = typename ::rclcpp::detail::assert_type_pair_is_specialized_type_adapter<
       CustomType,
       ROSMessageType
       >::type_adapter;
   };
   
   
   template<typename CustomType>
   struct ImplicitTypeAdapter
   {
     using is_specialized = std::false_type;
   };
   
   
   template<typename T>
   struct TypeAdapter<T, void, std::enable_if_t<ImplicitTypeAdapter<T>::is_specialized::value>>
     : ImplicitTypeAdapter<T>
   {};
   
   
   #define RCLCPP_USING_CUSTOM_TYPE_AS_ROS_MESSAGE_TYPE(CustomType, ROSMessageType) \
     template<> \
     struct rclcpp::ImplicitTypeAdapter<CustomType> \
       : public rclcpp::TypeAdapter<CustomType, ROSMessageType> \
     { \
       static_assert( \
         is_specialized::value, \
         "Cannot use custom type as ros type when there is no TypeAdapter for that pair"); \
     }
   
   }  // namespace rclcpp
   
   #endif  // RCLCPP__TYPE_ADAPTER_HPP_