stub out functions for getting pub/sub infos from topic name

Author: mm318

rclcpp/include/rclcpp/node_interfaces/node_graph.hpp

@@ -85,6 +85,18 @@ class NodeGraph : public NodeGraphInterface
   size_t
   count_subscribers(const std::string & topic_name) const override;
 
+  RCLCPP_PUBLIC
+  std::vector<rmw_topic_info_t>
+  get_publishers_info_by_topic(
+    const std::string & topic_name,
+    bool no_demangle = false) const override;
+
+  RCLCPP_PUBLIC
+  std::vector<rmw_topic_info_t>
+  get_subscriptions_info_by_topic(
+    const std::string & topic_name,
+    bool no_demangle = false) const override;
+
   RCLCPP_PUBLIC
 
   const rcl_guard_condition_t *

rclcpp/include/rclcpp/node_interfaces/node_graph_interface.hpp

@@ -22,6 +22,7 @@
 #include <vector>
 
 #include "rcl/guard_condition.h"
+#include "rmw/topic_info.h"
 
 #include "rclcpp/event.hpp"
 #include "rclcpp/macros.hpp"
@@ -89,6 +90,22 @@ class NodeGraphInterface
   size_t
   count_subscribers(const std::string & topic_name) const = 0;
 
+  /// Return a vector of publisher infos publishing to a given topic.
+  RCLCPP_PUBLIC
+  virtual
+  std::vector<rmw_topic_info_t>
+  get_publishers_info_by_topic(
+    const std::string & topic_name,
+    bool no_demangle = false) const = 0;
+
+  /// Return a vector of subscription infos publishing to a given topic.
+  RCLCPP_PUBLIC
+  virtual
+  std::vector<rmw_topic_info_t>
+  get_subscriptions_info_by_topic(
+    const std::string & topic_name,
+    bool no_demangle = false) const = 0;
+
   /// Return the rcl guard condition which is triggered when the ROS graph changes.
   RCLCPP_PUBLIC
   virtual

rclcpp/src/rclcpp/node_interfaces/node_graph.cpp

@@ -266,6 +266,22 @@ NodeGraph::count_subscribers(const std::string & topic_name) const
   return count;
 }
 
+std::vector<rmw_topic_info_t>
+NodeGraph::get_publishers_info_by_topic(
+  const std::string & /*topic_name*/,
+  bool /*no_demangle*/) const
+{
+  return std::vector<rmw_topic_info_t>();
+}
+
+std::vector<rmw_topic_info_t>
+NodeGraph::get_subscriptions_info_by_topic(
+  const std::string & /*topic_name*/,
+  bool /*no_demangle*/) const
+{
+  return std::vector<rmw_topic_info_t>();
+}
+
 const rcl_guard_condition_t *
 NodeGraph::get_graph_guard_condition() const
 {