text: // Copyright 2014 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__EXECUTORS__SINGLE_THREADED_EXECUTOR_HPP_
  #define RCLCPP__EXECUTORS__SINGLE_THREADED_EXECUTOR_HPP_
  
  #include <rmw/rmw.h>
  
  #include <cassert>
  #include <cstdlib>
  #include <memory>
  #include <vector>
  
  #include "rclcpp/executor.hpp"
  #include "rclcpp/macros.hpp"
  #include "rclcpp/memory_strategies.hpp"
  #include "rclcpp/node.hpp"
  #include "rclcpp/utilities.hpp"
  #include "rclcpp/rate.hpp"
  #include "rclcpp/visibility_control.hpp"
  
  namespace rclcpp
  {
  namespace executors
  {
  
  /// Single-threaded executor implementation.
  /**
   * This is the default executor created by rclcpp::spin.
   */
  class SingleThreadedExecutor : public rclcpp::Executor
  {
  public:
    RCLCPP_SMART_PTR_DEFINITIONS(SingleThreadedExecutor)
  
    /// Default constructor. See the default constructor for Executor.
    RCLCPP_PUBLIC
    explicit SingleThreadedExecutor(
      const rclcpp::ExecutorOptions & options = rclcpp::ExecutorOptions());
  
    /// Default destructor.
    RCLCPP_PUBLIC
    virtual ~SingleThreadedExecutor();
  
    /// Single-threaded implementation of spin.
    /**
     * This function will block until work comes in, execute it, and then repeat
     * the process until canceled.
     * It may be interrupt by a call to rclcpp::Executor::cancel() or by ctrl-c
     * if the associated context is configured to shutdown on SIGINT.
     */
    RCLCPP_PUBLIC
    void
    spin() override;
  
  private:
    RCLCPP_DISABLE_COPY(SingleThreadedExecutor)
  };
  
  }  // namespace executors
  }  // namespace rclcpp
  
  #endif  // RCLCPP__EXECUTORS__SINGLE_THREADED_EXECUTOR_HPP_
  