PySide6.QtScxml.QScxmlStateMachine

class QScxmlStateMachine

The QScxmlStateMachine class provides an interface to the state machines created from SCXML files. More…

Inheritance diagram of PySide6.QtScxml.QScxmlStateMachine

Synopsis

Properties

  • dataModelᅟ - Data model to be used for this state machine

  • initialValuesᅟ - Initial values to be used for setting up the data model

  • initializedᅟ - Whether the state machine has been initialized

  • invokedᅟ - Whether the state machine was invoked from an outer state machine

  • invokedServicesᅟ - A list of SCXML services that were invoked from the main state machine (possibly recursively)

  • loaderᅟ - That is currently used to resolve and load URIs for the state machine

  • nameᅟ - Of the state machine as set by the name attribute of the <scxml> tag

  • parseErrorsᅟ - List of parse errors that occurred while creating a state machine from an SCXML file

  • runningᅟ - The running state of this state machine

  • sessionIdᅟ - Session ID of the current state machine

  • tableDataᅟ - Table data that is used when generating C++ from an SCXML file

Methods

Slots

Signals

Static functions

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description

QScxmlStateMachine is an implementation of the State Chart XML (SCXML) .

All states that are defined in the SCXML file are accessible as properties of QScxmlStateMachine . These properties are boolean values and indicate whether the state is active or inactive.

Note

The QScxmlStateMachine needs a QEventLoop to work correctly. The event loop is used to implement the delay attribute for events and to schedule the processing of a state machine when events are received from nested (or parent) state machines.

Note

Properties can be used directly when from __feature__ import true_property is used or via accessor functions otherwise.

property dataModelᅟ: QScxmlDataModel

This property holds The data model to be used for this state machine..

SCXML data models are described in SCXML Specification - 5 Data Model and Data Manipulation . For more information about supported data models, see SCXML Compliance .

Changing the data model when the state machine has been initialized is not specified in the SCXML standard and leads to undefined behavior.

Access functions:
property initialValuesᅟ: Dictionary with keys of type .QString and values of type QVariant.

This property holds The initial values to be used for setting up the data model..

Access functions:
property initializedᅟ: bool

This property holds Whether the state machine has been initialized..

It is true if the state machine has been initialized, false otherwise.

Access functions:
property invokedᅟ: bool

This property holds Whether the state machine was invoked from an outer state machine..

true when the state machine was started as a service with the <invoke> element, false otherwise.

Access functions:
property invokedServicesᅟ: list of QScxmlInvokableService

This property holds A list of SCXML services that were invoked from the main state machine (possibly recursively)..

Access functions:
property loaderᅟ: Loader

This property holds The loader that is currently used to resolve and load URIs for the state machine..

Access functions:
property nameᅟ: str

This property holds The name of the state machine as set by the name attribute of the <scxml> tag..

Access functions:
property parseErrorsᅟ: list of QScxmlError

This property holds The list of parse errors that occurred while creating a state machine from an SCXML file..

Access functions:
property runningᅟ: bool

This property holds the running state of this state machine.

See also

start()

Access functions:
property sessionIdᅟ: str

This property holds The session ID of the current state machine..

The session ID is used for message routing between parent and child state machines. If a state machine is started by an <invoke> element, any event it sends will have the invokeid field set to the session ID. The state machine will use the origin of an event (which is set by the target or targetexpr attribute in a <send> element) to dispatch messages to the correct child state machine.

See also

invokeId()

Access functions:
property tableDataᅟ: QScxmlTableData

This property holds The table data that is used when generating C++ from an SCXML file..

The class implementing the state machine will use this property to assign the generated table data. The state machine does not assume ownership of the table data.

Access functions:
__init__(metaObject[, parent=None])
Parameters:
activeStateNames([compress=true])
Parameters:

compress – bool

Return type:

list of strings

Retrieves a list of state names of all active states.

When a state is active, all its parent states are active by definition. When compress is true (the default), the parent states will be filtered out and only the leaf states will be returned. When it is false, the full list of active states will be returned.

cancelDelayedEvent(sendId)
Parameters:

sendId – str

Cancels a delayed event with the specified sendId.

connectToEvent(scxmlEventSpec, receiver, method[, type=Qt.AutoConnection])
Parameters:
Return type:

Connection

Creates a connection of the specified type from the event specified by scxmlEventSpec to the method in the receiver object. The receiver’s method may take a QScxmlEvent as a parameter. For example:

void mySlot(const QScxmlEvent &event);

In contrast to event specifications in SCXML documents, spaces are not allowed in the scxmlEventSpec here. In order to connect to multiple events with different prefixes, connectToEvent() has to be called multiple times.

Returns a handle to the connection, which can be used later to disconnect.

connectToState(scxmlStateName, receiver, method[, type=Qt.AutoConnection])
Parameters:
Return type:

Connection

Creates a connection of the given type from the state identified by scxmlStateName to the method in the receiver object. The receiver’s method may take a boolean argument that indicates whether the state connected became active or inactive. For example:

void mySlot(bool active);

Returns a handle to the connection, which can be used later to disconnect.

dataModel()
Return type:

QScxmlDataModel

Returns the data model used by the state machine.

See also

setDataModel()

Getter of property dataModelᅟ .

dataModelChanged(model)
Parameters:

model – QScxmlDataModel

Notification signal of property dataModelᅟ .

finished()

This signal is emitted when the state machine reaches a top-level final state.

See also

running

static fromData(data[, fileName=""])
Parameters:
Return type:

QScxmlStateMachine

Creates a state machine by reading from the QIODevice specified by data.

This method will always return a state machine. If errors occur while reading the SCXML file, fileName, the state machine cannot be started. The errors can be retrieved by calling the parseErrors() method.

See also

parseErrors()

static fromFile(fileName)
Parameters:

fileName – str

Return type:

QScxmlStateMachine

Creates a state machine from the SCXML file specified by fileName.

This method will always return a state machine. If errors occur while reading the SCXML file, the state machine cannot be started. The errors can be retrieved by calling the parseErrors() method.

See also

parseErrors()

init()
Return type:

bool

Initializes the state machine.

State machine initialization consists of calling setup() , setting the initial values for <data> elements, and executing any <script> tags of the <scxml> tag. The initial data values are taken from the initialValues property.

Returns false if parse errors occur or if any of the initialization steps fail. Returns true otherwise.

initialValues()
Return type:

Dictionary with keys of type .QString and values of type QVariant.

See also

setInitialValues()

Getter of property initialValuesᅟ .

initialValuesChanged(initialValues)
Parameters:

initialValues – Dictionary with keys of type .QString and values of type QVariant.

Notification signal of property initialValuesᅟ .

initializedChanged(initialized)
Parameters:

initialized – bool

Notification signal of property initializedᅟ .

invokedServices()
Return type:

.list of QScxmlInvokableService

Getter of property invokedServicesᅟ .

invokedServicesChanged(invokedServices)
Parameters:

invokedServices – .list of QScxmlInvokableService

Notification signal of property invokedServicesᅟ .

isActive(scxmlStateName)
Parameters:

scxmlStateName – str

Return type:

bool

Returns true if the state specified by scxmlStateName is active, false otherwise.

isActive(stateIndex)
Parameters:

stateIndex – int

Return type:

bool

Returns true if the state with the ID stateIndex is active.

This method is part of the interface to the compiled representation of SCXML state machines. It should only be used internally and by state machines compiled from SCXML documents.

isDispatchableTarget(target)
Parameters:

target – str

Return type:

bool

Returns true if a message to target can be dispatched by this state machine.

Valid targets are:

  • #_parent for the parent state machine if the current state machine is started by <invoke>

  • #_internal for the current state machine

  • #_scxml_sessionid, where sessionid is the session ID of the current state machine

  • #_servicename, where servicename is the ID or name of a service started with <invoke> by this state machine

isInitialized()
Return type:

bool

Getter of property initializedᅟ .

isInvoked()
Return type:

bool

Getter of property invokedᅟ .

isRunning()
Return type:

bool

Returns true if the state machine is running, false otherwise.

Getter of property runningᅟ .

loader()
Return type:

Loader

See also

setLoader()

Getter of property loaderᅟ .

loaderChanged(loader)
Parameters:

loader – Loader

Notification signal of property loaderᅟ .

log(label, msg)
Parameters:

  • label – str

  • msg – str

This signal is emitted if a <log> tag is used in the SCXML. label is the value of the label attribute of the <log> tag. msg is the value of the evaluated expr attribute of the <log> tag. If there is no expr attribute, a null string will be returned.

name()
Return type:

str

Getter of property nameᅟ .

parseErrors()
Return type:

.list of QScxmlError

Getter of property parseErrorsᅟ .

reachedStableState()

This signal is emitted when the event queue is empty at the end of a macro step or when a final state is reached.

runningChanged(running)
Parameters:

running – bool

This signal is emitted when the running property is changed with running as argument.

Notification signal of property runningᅟ .

sessionId()
Return type:

str

Getter of property sessionIdᅟ .

setDataModel(model)
Parameters:

model – QScxmlDataModel

Sets the data model for this state machine to model. There is a 1:1 relation between state machines and models. After setting the model once you cannot change it anymore. Any further attempts to set the model using this method will be ignored.

See also

dataModel()

Setter of property dataModelᅟ .

setInitialValues(initialValues)
Parameters:

initialValues – Dictionary with keys of type .QString and values of type QVariant.

See also

initialValues()

Setter of property initialValuesᅟ .

setLoader(loader)
Parameters:

loader – Loader

See also

loader()

Setter of property loaderᅟ .

setRunning(running)
Parameters:

running – bool

Starts the state machine if running is true, or stops it otherwise.

Setter of property runningᅟ .

setTableData(tableData)
Parameters:

tableData – QScxmlTableData

See also

tableData()

Setter of property tableDataᅟ .

start()

Starts this state machine. When a final top-level state is entered, the machine will emit the finished() signal.

Note

A state machine will not run without a running event loop, such as the main application event loop started with QCoreApplication::exec() or QApplication::exec().

Note

Calling start() after stop() will not result in a full reset of its configuration yet, hence it is strongly advised not to do it.

Note

Starting a finished machine yields a warning.

See also

runningChanged() setRunning() stop() finished()

stateNames([compress=true])
Parameters:

compress – bool

Return type:

list of strings

Retrieves a list of state names of all states.

When compress is true (the default), the states that contain child states will be filtered out and only the leaf states will be returned. When it is false, the full list of all states will be returned.

The returned list does not contain the states of possible nested state machines.

Note

The order of the state names in the list is the order in which the states occurred in the SCXML document.

stop()

Stops this state machine. The machine will not execute any further state transitions. Its running property is set to false.

submitEvent(event)
Parameters:

event – QScxmlEvent

Submits the SCXML event event to the internal or external event queue depending on the priority of the event.

When a delay is set, the event will be queued for delivery after the timeout has passed. The state machine takes ownership of event and deletes it after processing.

submitEvent(eventName)
Parameters:

eventName – str

A utility method to create and submit an external event with the specified eventName as the name.

submitEvent(eventName, data)
Parameters:

  • eventName – str

  • data – object

A utility method to create and submit an external event with the specified eventName as the name and data as the payload data.

tableData()
Return type:

QScxmlTableData

See also

setTableData()

Getter of property tableDataᅟ .

tableDataChanged(tableData)
Parameters:

tableData – QScxmlTableData

Notification signal of property tableDataᅟ .