ex01_wrap_legacy.cpp

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#include "behaviortree_cpp/bt_factory.h"
#include "behaviortree_cpp/loggers/bt_cout_logger.h"
 
// This is my custom type. We won't know how to read this from a string,
// unless we implement convertFromString<Point3D>()
struct Point3D
{
  double x, y, z;
};
 
// We want to create an ActionNode that calls the method MyLegacyMoveTo::go
class MyLegacyMoveTo
{
public:
  bool go(Point3D goal)
  {
    printf("Going to: %f %f %f\n", goal.x, goal.y, goal.z);
    return true;  // true means success in my legacy code
  }
};
 
// Similarly to the previous tutorials, we need to implement this parsing method,
// providing a specialization of BT::convertFromString
namespace BT
{
template <>
Point3D convertFromString(StringView key)
{
  // three real numbers separated by semicolons
  auto parts = BT::splitString(key, ';');
  if(parts.size() != 3)
  {
    throw RuntimeError("invalid input)");
  }
  else
  {
    Point3D output;
    output.x = convertFromString<double>(parts[0]);
    output.y = convertFromString<double>(parts[1]);
    output.z = convertFromString<double>(parts[2]);
    return output;
  }
}
}  // namespace BT
 
// clang-format off
static const char* xml_text = R"(
 
 <root BTCPP_format="4">
     <BehaviorTree>
        <MoveTo  goal="-1;3;0.5" />
     </BehaviorTree>
 </root>
 )";
 
// clang-format on
 
int main()
{
  using namespace BT;
 
  MyLegacyMoveTo move_to;
 
  // Here we use a lambda that captures the reference of move_to
  auto MoveToWrapperWithLambda = [&move_to](TreeNode& parent_node) -> NodeStatus {
    Point3D goal;
    // thanks to paren_node, you can access easily the input and output ports.
    parent_node.getInput("goal", goal);
 
    bool res = move_to.go(goal);
    // convert bool to NodeStatus
    return res ? NodeStatus::SUCCESS : NodeStatus::FAILURE;
  };
 
  BehaviorTreeFactory factory;
 
  // Register the lambda with BehaviorTreeFactory::registerSimpleAction
 
  PortsList ports = { BT::InputPort<Point3D>("goal") };
  factory.registerSimpleAction("MoveTo", MoveToWrapperWithLambda, ports);
 
  auto tree = factory.createTreeFromText(xml_text);
 
  tree.tickWhileRunning();
 
  return 0;
}
 
/* Expected output:
 
Going to: -1.000000 3.000000 0.500000
 
*/