Proposed method templates to get vectors and maps from the ROS param server, to be added to <ros/param.h>.

roscpp_param_patch.h

/**
 * @file
 *
 * Proposed method templates to get vectors and maps from the ROS param server, to be added to <ros/param.h>.
 *
 * @date Aug 2, 2013
 * @author Bea Adkins
 */

#ifndef ROSCPP_PARAM_PATCH_H_
#define ROSCPP_PARAM_PATCH_H_

#include "ros/param.h"

namespace rospatch
{
namespace param
{

template<typename T> bool isXmlRpcValueType(XmlRpc::XmlRpcValue& t);

template<> bool isXmlRpcValueType<std::string>(XmlRpc::XmlRpcValue& v)
{
  return v.getType() == XmlRpc::XmlRpcValue::TypeString;
}

template<> bool isXmlRpcValueType<int>(XmlRpc::XmlRpcValue& v)
{
  return v.getType() == XmlRpc::XmlRpcValue::TypeInt;
}

template<> bool isXmlRpcValueType<double>(XmlRpc::XmlRpcValue& v)
{
  return v.getType() == XmlRpc::XmlRpcValue::TypeDouble;
}

template<> bool isXmlRpcValueType<bool>(XmlRpc::XmlRpcValue& v)
{
  return v.getType() == XmlRpc::XmlRpcValue::TypeBoolean;
}

// Hack to make patch functions copy-pasteable to roscpp/include/param.h
bool getImpl(const std::string &key, XmlRpc::XmlRpcValue &v, bool use_cache)
{
  if(use_cache)
    return ros::param::getCached(key, v);
  else
    return ros::param::get(key, v);
}

template<typename T> bool getImpl(const std::string& key, std::vector<T>& l, bool use_cache)
{
  using namespace ros;

  XmlRpc::XmlRpcValue v;
  if(!getImpl(key, v, use_cache))
    return false;
  if(v.getType() != XmlRpc::XmlRpcValue::TypeArray)
    return false;

  //l.empty(); // Do we want to clear the list or append?
  for(int32_t i = 0; i < v.size(); i++)
  {
    if(!isXmlRpcValueType<T>(v[i]))
      return false;
    l.push_back(static_cast<T>(v[i]));
  }

  return true;
}

template<typename T> bool getImpl(const std::string& key, std::map<std::string, T>& d, bool use_cache)
{
  using namespace ros;

  XmlRpc::XmlRpcValue v;
  if(!getImpl(key, v, use_cache))
    return false;
  if(v.getType() != XmlRpc::XmlRpcValue::TypeStruct)
    return false;

  // d.empty(); // Do we want to clear the map or append?
  for(XmlRpc::XmlRpcValue::iterator itr = v.begin();
      itr != v.end();
      itr++)
  {
    if(!isXmlRpcValueType<T>(itr->second))
      return false;
    const std::string& map_key = itr->first;
    const T& map_value = static_cast<T>(itr->second);
    d[map_key] = map_value;
  }

  return true;
}

template<typename T> bool get(const std::string& key, std::vector<std::string, T>& l)
{
  return getImpl(key, l, false);
}

template<typename T> bool get(const std::string& key, std::map<std::string, T>& d)
{
  return getImpl(key, d, false);
}

template<typename T> bool getCached(const std::string& key, std::vector<std::string, T>& l)
{
  return getImpl(key, l, true);
}

template<typename T> bool getCached(const std::string& key, std::map<std::string, T>& d)
{
  return getImpl(key, d, true);
}

} /* namespace param */
} /* namespace rospatch */

#endif /* ROSCPP_PARAM_PATCH_H_ */