Function detectMainTreeId

src/bt_factory.cpp:32–54

Extract the main tree ID from an XML root element. Checks main_tree_to_execute attribute first, then falls back to the single BehaviorTree ID if only one is defined.

// Checks main_tree_to_execute attribute first, then falls back to the
// single BehaviorTree ID if only one is defined.
std::string detectMainTreeId(const tinyxml2::XMLElement* xml_root)
{
  if(const auto* attr = xml_root->Attribute("main_tree_to_execute"))
  {
    return attr;
  }
  int bt_count = 0;
  std::string single_id;
  for(const auto* bt_elem = xml_root->FirstChildElement("BehaviorTree");
      bt_elem != nullptr; bt_elem = bt_elem->NextSiblingElement("BehaviorTree"))
  {
    bt_count++;
    if(const auto* tree_id = bt_elem->Attribute("ID"))
    {
      single_id = tree_id;
    }
  }
  if(bt_count == 1 && !single_id.empty())
  {
    return single_id;
  }
  return {};
}

// Load XML into parser and resolve which tree to instantiate.
// Returns the resolved tree ID (may be empty if parser should use default).