Method checkPreConditions

src/tree_node.cpp:204–259

}

Expected<NodeStatus> TreeNode::checkPreConditions()
{
  Ast::Environment env = { config().blackboard, config().enums };

  // Check pre-conditions in order: FAILURE_IF, SUCCESS_IF, SKIP_IF, WHILE_TRUE.
  // IMPORTANT: _failureIf, _successIf, and _skipIf are evaluated ONLY when the
  // node is IDLE or SKIPPED. They are NOT re-evaluated while the node is RUNNING.
  for(size_t index = 0; index < size_t(PreCond::COUNT_); index++)
  {
    const auto& parse_executor = _p->pre_parsed[index];
    if(!parse_executor)
    {
      continue;
    }

    const auto preID = static_cast<PreCond>(index);

    // _failureIf, _successIf, _skipIf: only checked when IDLE or SKIPPED
    // _while: checked here AND also when RUNNING (see below)
    if(_p->status == NodeStatus::IDLE || _p->status == NodeStatus::SKIPPED)
    {
      // what to do if the condition is true
      if(parse_executor(env).cast<bool>())
      {
        if(preID == PreCond::FAILURE_IF)
        {
          return NodeStatus::FAILURE;
        }
        if(preID == PreCond::SUCCESS_IF)
        {
          return NodeStatus::SUCCESS;
        }
        if(preID == PreCond::SKIP_IF)
        {
          return NodeStatus::SKIPPED;
        }
      }
      // if the conditions is false
      else if(preID == PreCond::WHILE_TRUE)
      {
        return NodeStatus::SKIPPED;
      }
    }
    else if(_p->status == NodeStatus::RUNNING && preID == PreCond::WHILE_TRUE)
    {
      // _while is the ONLY precondition checked while RUNNING.
      // If the condition becomes false, halt the node and return SKIPPED.
      if(!parse_executor(env).cast<bool>())
      {
        haltNode();
        return NodeStatus::SKIPPED;
      }
    }
  }
  return nonstd::make_unexpected("");  // no precondition
}

void TreeNode::checkPostConditions(NodeStatus status)