boring_string_publisher.cpp

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/* Author: David V. Lu!! */

#include <rclcpp/rclcpp.hpp>
#include <std_msgs/msg/string.hpp>
#include <fstream>
#include <sstream>
#include <sys/stat.h>

int main(int argc, char** argv)
{
  rclcpp::init(argc, argv);
  auto node = std::make_shared<rclcpp::Node>("boring_string_publisher");

  // Get Two String Parameters
  std::string topic, content_path;
  node->declare_parameter("topic", rclcpp::ParameterType::PARAMETER_STRING);
  node->get_parameter("topic", topic);
  node->declare_parameter("content_path", rclcpp::ParameterType::PARAMETER_STRING);
  node->get_parameter("content_path", content_path);

  if (content_path.empty())
  {
    RCLCPP_FATAL(node->get_logger(), "content_path parameter was not specified or is empty");
    return -1;
  }

  // Check if content exists
  struct stat statistics;
  if (stat(content_path.c_str(), &statistics) != 0)
  {
    RCLCPP_FATAL(node->get_logger(), "%s does not exist!", content_path.c_str());
    return -1;
  }

  // Set Up Publisher
  rclcpp::Publisher<std_msgs::msg::String>::SharedPtr string_publisher =
      node->create_publisher<std_msgs::msg::String>(topic, rclcpp::QoS(1).transient_local());

  // Read in Content
  std::ifstream content_stream(content_path.c_str());
  std::stringstream buffer;
  buffer << content_stream.rdbuf();

  // Publish Content
  std_msgs::msg::String msg;
  msg.data = buffer.str();
  string_publisher->publish(msg);

  rclcpp::spin(node);
  rclcpp::shutdown();
  return 0;
}