Abstract base class for Behavior Tree Nodes. More...

#include <tree_node.h>

Inheritance diagram for BT::TreeNode:

[legend]

Public Types
typedef std::shared_ptr< TreeNode >	Ptr

using	StatusChangeSignal = Signal< TimePoint, const TreeNode &, NodeStatus, NodeStatus >

using	StatusChangeSubscriber = StatusChangeSignal::Subscriber

using	StatusChangeCallback = StatusChangeSignal::CallableFunction

using	PreTickCallback = std::function< NodeStatus(TreeNode &)>

using	PostTickCallback = std::function< NodeStatus(TreeNode &, NodeStatus)>

using	TickMonitorCallback = std::function< void(TreeNode &, NodeStatus, std::chrono::microseconds)>

Public Member Functions
	TreeNode (std::string name, NodeConfig config)
	TreeNode main constructor.

	TreeNode (const TreeNode &other)=delete

TreeNode &	operator= (const TreeNode &other)=delete

	TreeNode (TreeNode &&other) noexcept

TreeNode &	operator= (TreeNode &&other) noexcept

virtual BT::NodeStatus	executeTick ()
	The method that should be used to invoke tick() and setStatus();.

void	haltNode ()

bool	isHalted () const

NodeStatus	status () const

const std::string &	name () const
	Name of the instance, not the type.

BT::NodeStatus	waitValidStatus ()

virtual NodeType	type () const =0

StatusChangeSubscriber	subscribeToStatusChange (StatusChangeCallback callback)
	subscribeToStatusChange is used to attach a callback to a status change. When StatusChangeSubscriber goes out of scope (it is a shared_ptr) the callback is unsubscribed automatically.

void	setPreTickFunction (PreTickCallback callback)

void	setPostTickFunction (PostTickCallback callback)

void	setTickMonitorCallback (TickMonitorCallback callback)

uint16_t	UID () const

const std::string &	fullPath () const

const std::string &	registrationName () const
	registrationName is the ID used by BehaviorTreeFactory to create an instance.

const NodeConfig &	config () const

template<typename T >
Result	getInput (const std::string &key, T &destination) const

template<typename T >
Expected< Timestamp >	getInputStamped (const std::string &key, T &destination) const
	getInputStamped is similar to getInput(dey, destination), but it returns also the Timestamp object, that can be used to check if a value was updated and when.

template<typename T >
Expected< T >	getInput (const std::string &key) const

template<typename T >
Expected< StampedValue< T > >	getInputStamped (const std::string &key) const

template<typename T >
Result	setOutput (const std::string &key, const T &value)
	setOutput modifies the content of an Output port

AnyPtrLocked	getLockedPortContent (const std::string &key)
	getLockedPortContent should be used when:

StringView	getRawPortValue (const std::string &key) const

void	emitWakeUpSignal ()
	Notify that the tree should be ticked again()

bool	requiresWakeUp () const

Static Public Member Functions
static bool	isBlackboardPointer (StringView str, StringView *stripped_pointer=nullptr)
	Check a string and return true if it matches the pattern: {...}.

static StringView	stripBlackboardPointer (StringView str)

static Expected< StringView >	getRemappedKey (StringView port_name, StringView remapped_port)

template<class DerivedT , typename... ExtraArgs>
static std::unique_ptr< TreeNode >	Instantiate (const std::string &name, const NodeConfig &config, ExtraArgs... args)

Protected Types
using	PreScripts = std::array< ScriptFunction, size_t(PreCond::COUNT_)>

using	PostScripts = std::array< ScriptFunction, size_t(PostCond::COUNT_)>

Protected Member Functions
NodeConfig &	config ()

virtual BT::NodeStatus	tick ()=0
	Method to be implemented by the user.

void	resetStatus ()
	Set the status to IDLE.

void	setRegistrationID (StringView ID)

void	setWakeUpInstance (std::shared_ptr< WakeUpSignal > instance)

void	modifyPortsRemapping (const PortsRemapping &new_remapping)

void	setStatus (NodeStatus new_status)
	setStatus changes the status of the node. it will throw if you try to change the status to IDLE, because your parent node should do that, not the user!

PreScripts &	preConditionsScripts ()

PostScripts &	postConditionsScripts ()

template<typename T >
T	parseString (const std::string &str) const

Friends
class	BehaviorTreeFactory

class	DecoratorNode

class	ControlNode

class	Tree

Detailed Description

Abstract base class for Behavior Tree Nodes.

Constructor & Destructor Documentation

◆ TreeNode()

BT::TreeNode::TreeNode	(	std::string	name,
		NodeConfig	config
	)

TreeNode main constructor.

Parameters

name	name of the instance, not the type.
config	information about input/output ports. See NodeConfig

Note: If your custom node has ports, the derived class must implement:

static PortsList providedPorts();

Member Function Documentation

◆ config()

const NodeConfig & BT::TreeNode::config ( ) const

Configuration passed at construction time. Can never change after the creation of the TreeNode instance.

◆ executeTick()

virtual BT::NodeStatus BT::TreeNode::executeTick ( )

virtual

The method that should be used to invoke tick() and setStatus();.

Reimplemented in BT::SyncActionNode, BT::DecoratorNode, BT::ThreadedAction, and BT::CoroActionNode.

◆ fullPath()

const std::string & BT::TreeNode::fullPath ( ) const

Human readable identifier, that includes the hierarchy of Subtrees See tutorial 10 as an example.

◆ getInput() [1/2]

template<typename T >

Expected< T > BT::TreeNode::getInput ( const std::string & key ) const

inline

Same as bool getInput(const std::string& key, T& destination) but using optional.

Parameters

key	the name of the port.

◆ getInput() [2/2]

template<typename T >

Result BT::TreeNode::getInput	(	const std::string &	key,
		T &	destination
	)		const

inline

Read an input port, which, in practice, is an entry in the blackboard. If the blackboard contains a std::string and T is not a string, convertFromString<T>() is used automatically to parse the text.

Parameters

key	the name of the port.
destination	reference to the object where the value should be stored

Returns: false if an error occurs.

◆ getInputStamped() [1/2]

template<typename T >

Expected< StampedValue< T > > BT::TreeNode::getInputStamped ( const std::string & key ) const

inline

Same as bool getInputStamped(const std::string& key, T& destination) but return StampedValue<T>

Parameters

key	the name of the port.

◆ getInputStamped() [2/2]

template<typename T >

Expected< Timestamp > BT::TreeNode::getInputStamped	(	const std::string &	key,
		T &	destination
	)		const

inline

getInputStamped is similar to getInput(dey, destination), but it returns also the Timestamp object, that can be used to check if a value was updated and when.

Parameters

key	the name of the port.
destination	reference to the object where the value should be stored

◆ getLockedPortContent()

AnyPtrLocked BT::TreeNode::getLockedPortContent ( const std::string & key )

getLockedPortContent should be used when:

your port contains an object with reference semantic (usually a smart pointer)
you want to modify the object we are pointing to.
you are concerned about thread-safety.

For example, if your port has type std::shared_ptr<Foo>, the code below is NOT thread safe:

auto foo_ptr = getInput<std::shared_ptr<Foo>>("port_name"); // modifying the content of foo_ptr is NOT thread-safe

What you must do, instead, to guaranty thread-safety, is:

if(auto any_ref = getLockedPortContent("port_name")) { Any* any = any_ref.get(); auto foo_ptr = any->cast<std::shared_ptr<Foo>>(); // modifying the content of foo_ptr inside this scope IS thread-safe }

It is important to destroy the object AnyPtrLocked, to release the lock.

NOTE: this method doesn't work, if the port contains a static string, instead of a blackboard pointer.

Parameters

key	the identifier of the port.

Returns: empty AnyPtrLocked if the blackboard entry doesn't exist or the content of the port was a static string.

◆ Instantiate()

template<class DerivedT , typename... ExtraArgs>

static std::unique_ptr< TreeNode > BT::TreeNode::Instantiate	(	const std::string &	name,
		const NodeConfig &	config,
		ExtraArgs...	args
	)

inlinestatic

Used to inject config into a node, even if it doesn't have the proper constructor

◆ setOutput()

template<typename T >

Result BT::TreeNode::setOutput	(	const std::string &	key,
		const T &	value
	)

inline

setOutput modifies the content of an Output port

Parameters

key	the name of the port.
value	new value

Returns: valid Result, if successful.

◆ setPostTickFunction()

void BT::TreeNode::setPostTickFunction ( PostTickCallback callback )

This method attaches to the TreeNode a callback with signature:

NodeStatus myCallback(TreeNode& node, NodeStatus status)

This callback is executed AFTER the tick() and, if it returns SUCCESS or FAILURE, the value returned by the actual tick() is overridden with this one.

◆ setPreTickFunction()

void BT::TreeNode::setPreTickFunction ( PreTickCallback callback )

This method attaches to the TreeNode a callback with signature:

 NodeStatus callback(TreeNode& node)

This callback is executed BEFORE the tick() and, if it returns SUCCESS or FAILURE, the actual tick() will NOT be executed and this result will be returned instead.

This is useful to inject a "dummy" implementation of the TreeNode at run-time

◆ setTickMonitorCallback()

void BT::TreeNode::setTickMonitorCallback ( TickMonitorCallback callback )

This method attaches to the TreeNode a callback with signature:

void myCallback(TreeNode& node, NodeStatus status, std::chrono::microseconds duration)

This callback is executed AFTER the tick() and will inform the user about its status and the execution time. Works only if the tick was not substituted by a pre-condition.

◆ subscribeToStatusChange()

StatusChangeSubscriber BT::TreeNode::subscribeToStatusChange ( StatusChangeCallback callback )

subscribeToStatusChange is used to attach a callback to a status change. When StatusChangeSubscriber goes out of scope (it is a shared_ptr) the callback is unsubscribed automatically.

Parameters

callback The callback to be execute when status change.

Returns: the subscriber handle.

◆ tick()

virtual BT::NodeStatus BT::TreeNode::tick ( )

protectedpure virtual

Method to be implemented by the user.

Implemented in BT::PopFromQueue< T >, BT::QueueSize< T >, BT::SimpleConditionNode, BT::SequenceNode, BT::SimpleDecoratorNode, BT::ConsumeQueue< T >, BT::LoopNode< T >, BT::SubTreeNode, BT::SimpleActionNode, and BT::StatefulActionNode.

◆ UID()

uint16_t BT::TreeNode::UID ( ) const

The unique identifier of this instance of treeNode. It is assigneld by the factory

◆ waitValidStatus()

BT::NodeStatus BT::TreeNode::waitValidStatus ( )

Blocking function that will sleep until the setStatus() is called with either RUNNING, FAILURE or SUCCESS.

The documentation for this class was generated from the following file:

include/behaviortree_cpp/tree_node.h

Public Types

Public Member Functions

Static Public Member Functions

Protected Types

Protected Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ TreeNode()

Member Function Documentation

◆ config()

◆ executeTick()

◆ fullPath()

◆ getInput() [1/2]

◆ getInput() [2/2]

◆ getInputStamped() [1/2]

◆ getInputStamped() [2/2]

◆ getLockedPortContent()

◆ Instantiate()

◆ setOutput()

◆ setPostTickFunction()

◆ setPreTickFunction()

◆ setTickMonitorCallback()

◆ subscribeToStatusChange()

◆ tick()

◆ UID()

◆ waitValidStatus()