switch_node.h

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/* Copyright (C) 2020-2022 Davide Faconti -  All Rights Reserved
*
*   Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"),
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*   and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
*   The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
*
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*/

#pragma once

#include "behaviortree_cpp_v3/control_node.h"

namespace BT
{
template <size_t NUM_CASES>
class SwitchNode : public ControlNode
{
public:
  SwitchNode(const std::string& name, const BT::NodeConfiguration& config) :
    ControlNode::ControlNode(name, config), running_child_(-1)
  {
    setRegistrationID("Switch");
  }

  virtual ~SwitchNode() override = default;

  void halt() override
  {
    running_child_ = -1;
    ControlNode::halt();
  }

  static PortsList providedPorts()
  {
    PortsList ports;
    ports.insert(BT::InputPort<std::string>("variable"));
    for (unsigned i = 0; i < NUM_CASES; i++)
    {
      char case_str[20];
      sprintf(case_str, "case_%d", i + 1);
      ports.insert(BT::InputPort<std::string>(case_str));
    }
    return ports;
  }

private:
  int running_child_;
  virtual BT::NodeStatus tick() override;
};

template <size_t NUM_CASES>
inline NodeStatus SwitchNode<NUM_CASES>::tick()
{
  if (childrenCount() != NUM_CASES + 1)
  {
    throw LogicError("Wrong number of children in SwitchNode; "
                     "must be (num_cases + default)");
  }

  std::string variable;
  std::string value;
  int match_index = int(NUM_CASES);   // default index;

  if (getInput("variable", variable))   // no variable? jump to default
  {
    // check each case until you find a match
    for (int index = 0; index < int(NUM_CASES); ++index)
    {
      char case_key[20];
      sprintf(case_key, "case_%d", int(index + 1));
      bool found = static_cast<bool>(getInput(case_key, value));

      if (found && variable == value)
      {
        match_index = index;
        break;
      }
    }
  }

  // if another one was running earlier, halt it
  if (running_child_ != -1 && running_child_ != match_index)
  {
    haltChild(running_child_);
  }

  auto& selected_child = children_nodes_[match_index];
  NodeStatus ret = selected_child->executeTick();
  if (ret == NodeStatus::RUNNING)
  {
    running_child_ = match_index;
  }
  else
  {
    resetChildren();
    running_child_ = -1;
  }
  return ret;
}

}   // namespace BT