t07_wrap_legacy.cpp

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#include "behaviortree_cpp_v3/bt_factory.h"
#include "behaviortree_cpp_v3/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;
    }
}
} // end anmespace BT


// clang-format off
static const char* xml_text = R"(

 <root>
     <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.tickRoot();

    return 0;
}

/* Expected output:

Going to: -1.000000 3.000000 0.500000

*/