This Node源码分析

看军哥博客有Rtos的源码分析,手痒耍宝把自己读的源码笔记分享出来.愿与众君互相讨论学习

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namespace ros

{

namespace names

{

void init(const M_string& remappings);

}

namespace this_node

{

std::string g_name = "empty";

std::string g_namespace;

const std::string& getName()    //获取当前的名字

{

  return g_name;

}

const std::string& getNamespace()   //获取当前命名空间

{

  return g_namespace;

}

void getAdvertisedTopics(V_string& topics)  //返回实例的发布者话题名

{

  TopicManager::instance()->getAdvertisedTopics(topics);

}

void getSubscribedTopics(V_string& topics)  //返回实例的订阅者话题名

{

  TopicManager::instance()->getSubscribedTopics(topics);

}

void init(const std::string& name, const M_string& remappings, uint32_t options)    //这前面还有argc argv 才是节点名

{

  char *ns_env = NULL;

#ifdef _MSC_VER //ROS绝逼是在Win下开发的`_^`

  _dupenv_s(&ns_env, NULL, "ROS_NAMESPACE");    //从环境中取字符串,获取环境变量的值

#else

  ns_env = getenv("ROS_NAMESPACE"); //在这里去环境变量应该指的就是命名空间惹

#endif

  if (ns_env)

  {

    g_namespace = ns_env;   //获取的命名空间值和当前命名空间相等

#ifdef _MSC_VER

    free(ns_env);

#endif

  }

  g_name = name;    //节点名给全局

  bool disable_anon = false;

  M_string::const_iterator it = remappings.find("__name");  //关联容器重命名,不知道它想干啥,看着一堆宏头大了

  if (it != remappings.end())

  {

    g_name = it->second;

    disable_anon = true;

  }

  it = remappings.find("__ns");

  if (it != remappings.end())

  {

    g_namespace = it->second;

  }

  if (g_namespace.empty())

  {

    g_namespace = "/";

  }

  g_namespace = (g_namespace == "/")

    ? std::string("/") 

    : ("/" + g_namespace)

    ;

  std::string error;

  if (!names::validate(g_namespace, error)) //若检测到命名空间非有效数据,报错

  {

    std::stringstream ss;

    ss << "Namespace [" << g_namespace << "] is invalid: " << error;

    throw InvalidNameException(ss.str());

  }

  // names must be initialized here, because it requires the namespace to already be known so that it can properly resolve names.

  // It must be done before we resolve g_name, because otherwise the name will not get remapped.

  //还不太明白它的重映射功能

  names::init(remappings);  //还是不懂重映射==

  if (g_name.find("/") != std::string::npos)    //nops的定义static const size_type npos = -1;

  {

    throw InvalidNodeNameException(g_name, "node names cannot contain /");

  }

  if (g_name.find("~") != std::string::npos)

  {

    throw InvalidNodeNameException(g_name, "node names cannot contain ~");

  }

  g_name = names::resolve(g_namespace, g_name); //resolve名字,全名/+ns+name

  if (options & init_options::AnonymousName && !disable_anon)   //init_options::AnonymousName:  匿名节点,在你的节点名后面加一些数字使它变得unique

  {

    char buf[200];

    snprintf(buf, sizeof(buf), "_%llu", (unsigned long long)WallTime::now().toNSec());

    g_name += buf;

  }

  ros::console::setFixedFilterToken("node", g_name);    //把节点和名字联系起来

}

} // namespace this_node

} // namespace ros

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下午写了一下午程序,快五点了不想继续写了,就发this node出来,又惊叹一番,回去看C++ 了bye~