Service Type Adaptations

rclcpp/include/rclcpp/get_service_type_support_handle.hpp

@@ -0,0 +1,97 @@
+// Copyright 2023 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__GET_SERVICE_TYPE_SUPPORT_HANDLE_HPP_
+#define RCLCPP__GET_SERVICE_TYPE_SUPPORT_HANDLE_HPP_
+
+#include <stdexcept>
+#include <type_traits>
+
+#include "rosidl_runtime_cpp/traits.hpp"
+#include "rosidl_runtime_cpp/service_type_support_decl.hpp"
+#include "rosidl_typesupport_cpp/service_type_support.hpp"
+
+#include "rclcpp/type_adapter.hpp"
+#include "type_adapter.hpp"
+
+namespace rclcpp
+{
+
+#ifdef DOXYGEN_ONLY
+
+/// Returns the service type support for the given `ServiceT` type.
+/**
+ * \tparam ServiceT an actual ROS service type or an adapted type using `rclcpp::TypeAdapter`
+ */
+template<typename ServiceT>
+constexpr const rosidl_service_type_support_t & get_service_type_support_handle();
+
+#else
+
+template<typename ServiceT>
+constexpr
+std::enable_if_t<
+  rosidl_generator_traits::is_service<ServiceT>::value,
+  const rosidl_service_type_support_t &
+>
+get_service_type_support_handle()
+{
+  auto handle = rosidl_typesupport_cpp::get_service_type_support_handle<ServiceT>();
+  if (!handle) {
+    throw std::runtime_error("Type support handle unexpectedly nullptr");
+  }
+  return *handle;
+}
+
+/// Checking the TypeAdapter struct when using custom or ROS types.
+template<typename AdaptedTypeStruct>
+constexpr
+std::enable_if_t<
+  !rosidl_generator_traits::is_service<AdaptedTypeStruct>::value &&
+  rclcpp::TypeAdapter<AdaptedTypeStruct>::is_specialized::value,
+  const rosidl_service_type_support_t &
+>
+get_service_type_support_handle()
+{
+  using CustomType = typename TypeAdapter<AdaptedTypeStruct>::ros_message_type;
+  auto handle = rosidl_typesupport_cpp::get_service_type_support_handle<CustomType>();
+
+  if (!handle) {
+    throw std::runtime_error("Type support handle unexpectedly nullptr");
+  }
+  return *handle;
+}
+
+// This specialization is a pass through runtime check, which allows a better
+// static_assert to catch this issue further down the line.
+// This should never get to be called in practice, and is purely defensive.
+template<typename AdaptedTypeStruct>
+constexpr
+typename std::enable_if_t<
+  !rosidl_generator_traits::is_service<AdaptedTypeStruct>::value &&
+  !TypeAdapter<AdaptedTypeStruct>::is_specialized::value,
+  const rosidl_service_type_support_t &
+>
+get_service_type_support_handle()
+{
+  throw std::runtime_error(
+          "this specialization of rclcpp::get_service_type_support_handle() "
+          "should never be called");
+}
+
+#endif  // DOXYGEN_ONLY
+
+}  // namespace rclcpp
+
+#endif  // RCLCPP__GET_SERVICE_TYPE_SUPPORT_HANDLE_HPP_

rclcpp/include/rclcpp/is_ros_compatible_type.hpp

@@ -30,6 +30,14 @@ struct is_ros_compatible_type
     rclcpp::TypeAdapter<T>::is_specialized::value;
 };
 
+template<typename T>
+struct is_ros_compatible_service_type
+{
+  static constexpr bool value =
+    rosidl_generator_traits::is_service<T>::value ||
+    rclcpp::TypeAdapter<T>::is_specialized::value;
+};
+
 }  // namespace rclcpp
 
 #endif  // RCLCPP__IS_ROS_COMPATIBLE_TYPE_HPP_