Cmake infrastructure for creating components (#784)

*cmake macro to create components for libraries with multiple nodes

Signed-off-by: Siddharth Kucheria <kucheria@usc.edu>

rclcpp_components/CMakeLists.txt

@@ -41,6 +41,11 @@ ament_target_dependencies(component_container
   "rclcpp"
 )
 
+set(node_main_template_install_dir "share/${PROJECT_NAME}")
+install(FILES
+  src/node_main.cpp.in
+  DESTINATION ${node_main_template_install_dir})
+
 add_executable(
   component_container_mt
   src/component_container_mt.cpp
@@ -119,4 +124,4 @@ install(
 ament_export_include_directories(include)
 ament_export_dependencies(class_loader)
 ament_export_dependencies(rclcpp)
-ament_package(CONFIG_EXTRAS rclcpp_components-extras.cmake)
+ament_package(CONFIG_EXTRAS rclcpp_components-extras.cmake.in)

rclcpp_components/cmake/rclcpp_components_register_node.cmake

@@ -0,0 +1,52 @@
+# Copyright 2019 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.
+#
+# usage: rclcpp_components_register_node(
+#        <target> PLUGIN <component> EXECUTABLE <node>)
+#
+# Register an rclcpp component with the ament
+# resource index and create an executable.
+#
+# :param target: the shared library target
+# :type target: string
+# :param PLUGIN: the plugin name
+# :type PLUGIN: string
+# :type EXECUTABLE: the node's executable name
+# :type EXECUTABLE: string
+#
+macro(rclcpp_components_register_node target)
+  cmake_parse_arguments(ARGS "" "PLUGIN;EXECUTABLE" "" ${ARGN})
+  set(component ${ARGS_PLUGIN})
+  set(node ${ARGS_EXECUTABLE})
+  _rclcpp_components_register_package_hook()
+  set(_path "lib")  
+  set(library_name "$<TARGET_FILE_NAME:${target}>")
+  if(WIN32)
+    set(_path "bin")
+  endif()
+  set(_RCLCPP_COMPONENTS__NODES
+    "${_RCLCPP_COMPONENTS__NODES}${component};${_path}/$<TARGET_FILE_NAME:${target}>\n")
+  configure_file(${rclcpp_components_NODE_TEMPLATE}
+    ${PROJECT_BINARY_DIR}/node_main_configured.cpp.in)
+  file(GENERATE OUTPUT ${PROJECT_BINARY_DIR}/rclcpp_components/node_main_${node}.cpp
+    INPUT ${PROJECT_BINARY_DIR}/node_main_configured.cpp.in)
+  add_executable(${node} ${PROJECT_BINARY_DIR}/rclcpp_components/node_main_${node}.cpp)
+  ament_target_dependencies(${node}
+    "rclcpp"
+    "class_loader"
+    "rclcpp_components")
+  install(TARGETS
+    ${node}
+    DESTINATION lib/${PROJECT_NAME})
+endmacro()

rclcpp_components/rclcpp_components-extras.cmake.in

@@ -25,5 +25,7 @@ macro(_rclcpp_components_register_package_hook)
   endif()
 endmacro()
 
-include("${rclcpp_components_DIR}/rclcpp_components_register_nodes.cmake")
+set(@PROJECT_NAME@_NODE_TEMPLATE "@CMAKE_INSTALL_PREFIX@/@node_main_template_install_dir@/node_main.cpp.in")
 
+include("${rclcpp_components_DIR}/rclcpp_components_register_nodes.cmake")
+include("${rclcpp_components_DIR}/rclcpp_components_register_node.cmake")

rclcpp_components/src/node_main.cpp.in

@@ -0,0 +1,66 @@
+// Copyright 2019 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.
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "class_loader/class_loader.hpp"
+#include "rclcpp/rclcpp.hpp"
+#include "rclcpp_components/node_factory.hpp"
+#include "rclcpp_components/node_factory_template.hpp"
+
+#define NODE_MAIN_LOGGER_NAME "@node@"
+
+int main(int argc, char * argv[])
+{
+  auto args = rclcpp::init_and_remove_ros_arguments(argc, argv);
+  rclcpp::Logger logger = rclcpp::get_logger(NODE_MAIN_LOGGER_NAME);
+  rclcpp::executors::SingleThreadedExecutor exec;
+  rclcpp::NodeOptions options;
+  options.arguments(args);
+  std::vector<class_loader::ClassLoader * > loaders;
+  std::vector<rclcpp_components::NodeInstanceWrapper> node_wrappers;
+
+  std::string library_name = "@library_name@";
+  std::string class_name = "rclcpp_components::NodeFactoryTemplate<@component@>";
+
+  RCLCPP_DEBUG(logger, "Load library %s", library_name.c_str());
+  auto loader = new class_loader::ClassLoader(library_name);
+  auto classes = loader->getAvailableClasses<rclcpp_components::NodeFactory>();
+  for (auto clazz : classes) {
+    std::string name = clazz.c_str();
+    if (!(name.compare(class_name))) {
+      RCLCPP_DEBUG(logger, "Instantiate class %s", clazz.c_str());
+      auto node_factory = loader->createInstance<rclcpp_components::NodeFactory>(clazz);
+      auto wrapper = node_factory->create_node_instance(options);
+      auto node = wrapper.get_node_base_interface();
+      node_wrappers.push_back(wrapper);
+      exec.add_node(node);
+    }
+  }
+  loaders.push_back(loader);
+
+
+  exec.spin();
+
+  for (auto wrapper : node_wrappers) {
+    exec.remove_node(wrapper.get_node_base_interface());
+  }
+  node_wrappers.clear();
+
+  rclcpp::shutdown();
+
+  return 0;
+}