ca.uqac.lif.ecp.statechart

Class Statechart<T extends Event>

java.lang.Object

ca.uqac.lif.ecp.statechart.Statechart<T>

Type Parameters:

T - The type of the events (i.e. the transition labels)

Direct Known Subclasses:

AtomicStatechart

public class Statechart<T extends Event>
extends java.lang.Object

Representation of a UML statechart. Currently, the implementation of UML statecharts imposes the following constraints and peculiarities:

• A transition cannot cross the boundary of an orthogonal region. However, transitions from the box surrounding a group of orthogonal regions to somewhere else are allowed.
• If no transition can fire on a given input event, the statechart moves to an implicit "trash" state and stays there forever. This propagates upwards, so a statechart enclosed within another one will provoke the same effect on its "parent" statechart.

Author:

Sylvain Hallé

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_currentState The ID of the current state in the execution of the statechart
protected int	m_initialState The ID of the initial state.
protected java.util.Map<java.lang.String,java.lang.Object>	m_initialValues The initial value of the state variables of this statechart
java.lang.String	m_name The name given to this statechart
protected Statechart<T>	m_parent The parent statechart, if any
protected State<T>	m_trashState A special sink state to make sure the transition relation is total
protected TrashTransition<T>	m_trashTransition An instance of the trash transition
protected java.util.Map<java.lang.String,java.lang.Object>	m_variables The state variables of this statechart
static java.lang.String	TRASH Label given to the trash sink in the statechart
static java.lang.String	UP Symbol indicating that the target of a transition refers to a state in the parent of the current statechart

Constructor Summary

Constructors

Constructor and Description
Statechart() Creates a new anonymous statechart
Statechart(java.lang.String name) Creates a new empty statechart

Method Summary

Modifier and Type	Method and Description
Statechart<T>	add(int source, Transition<T> transition) Adds a new transition to the statechart
Statechart<T>	add(State<T> s) Adds a new state to this statechart
Statechart<T>	add(java.lang.String source_name, Transition<T> transition) Adds a new transition to the statechart
boolean	applyTransition(T event, Configuration<T> node) Attempts to apply a transition on this statechart
Statechart<T>	clone(Statechart<T> parent) Creates a copy of this statechart
static Statechart<?>	findOwner(Statechart<?> statechart, java.lang.String var_name) Finds the statechart instance that "owns" the state variable of given name.
Statechart<?>	findOwner(java.lang.String var_name) Finds the statechart instance that "owns" the state variable of given name.
State<T>	getAnyAtomicChild() Returns an arbitrary state of this statechart that is not a NestedState.
State<T>	getAnyAtomicChild(State<T> state) Returns an arbitrary state of this statechart that is not a NestedState and is contained within the state given as argument.
Configuration<T>	getCurrentConfiguration() Gets the identifier of the current state of the statechart.
int	getEdgeCount() Counts the edges in this statechart
Configuration<T>	getInitialConfiguration() Gets the initial configuration of this statechart
State<T>	getInitialState() Gets the initial state of this statechart
Statechart<T>	getParent() Gets the enclosing instance of this statechart
State<T>	getState(int id) Gets a state with given ID
protected State<T>	getState(java.lang.String name) Gets a state with given name
java.util.Map<java.lang.String,State<T>>	getStates() Gets the states of this statechart
java.util.Map<java.lang.Integer,java.util.Set<Transition<T>>>	getTransitions()
java.lang.Object	getVariable(java.lang.String var_name) Gets the value of a state variable
boolean	hasVariable(java.lang.String var_name) Checks if a statechart has a variable of given name
protected void	putAllStateVariables(Statechart<T> sc)
Statechart<T>	reset() Resets the statechart to its initial configuration
Statechart<T>	setParent(Statechart<T> parent) Sets the enclosing instance of this statechart
void	setTransitions(java.util.Map<java.lang.Integer,java.util.Set<Transition<T>>> m_transitions)
Statechart<T>	setVariable(java.lang.String name, java.lang.Object value) Sets the value of a state variable.
Transition<T>	takeTransition(T event) Takes a transition in this statechart with the given event

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

UP

public static final java.lang.String UP

Symbol indicating that the target of a transition refers to a state in the parent of the current statechart

See Also:

Constant Field Values

TRASH

public static final java.lang.String TRASH

Label given to the trash sink in the statechart

See Also:

Constant Field Values

m_name

public final java.lang.String m_name

The name given to this statechart

m_trashTransition

protected final TrashTransition<T extends Event> m_trashTransition

An instance of the trash transition

m_currentState

protected int m_currentState

The ID of the current state in the execution of the statechart

m_initialState

protected int m_initialState

The ID of the initial state. 0 by default.

m_trashState

protected final State<T extends Event> m_trashState

A special sink state to make sure the transition relation is total

m_parent

protected Statechart<T extends Event> m_parent

The parent statechart, if any

m_variables

protected java.util.Map<java.lang.String,java.lang.Object> m_variables

The state variables of this statechart

m_initialValues

protected java.util.Map<java.lang.String,java.lang.Object> m_initialValues

The initial value of the state variables of this statechart

Constructor Detail

Statechart

public Statechart(java.lang.String name)

Creates a new empty statechart

Parameters:

name - The name given to this statechart

Statechart

public Statechart()

Creates a new anonymous statechart

Method Detail

setVariable

public Statechart<T> setVariable(java.lang.String name,
                                 java.lang.Object value)

Sets the value of a state variable. If the variable does not yet exist in this statechart, the value this variable is given is kept as the "initial" value. When resetting the statechart (or cloning it), the variable will be set back to this value.

Parameters:

name - The name of the variable

value - The value of the variable

Returns:

This statechart

setParent

public Statechart<T> setParent(Statechart<T> parent)

Sets the enclosing instance of this statechart

Parameters:

parent - The instance

Returns:

This statechart

getParent

public Statechart<T> getParent()

Gets the enclosing instance of this statechart

Returns:

The instance, or null if this statechart has no parent

getState

public State<T> getState(int id)

Gets a state with given ID

Parameters:

id - The ID

Returns:

The state, or null if no state exists with such ID

getAnyAtomicChild

public State<T> getAnyAtomicChild()

Returns an arbitrary state of this statechart that is not a NestedState. The method recurses inside nested states if the statechart only has nested states. This method is mostly used for the graphical rendering of a statechart.

Returns:

A state, or null if no such state exists

getAnyAtomicChild

public State<T> getAnyAtomicChild(State<T> state)

Returns an arbitrary state of this statechart that is not a NestedState and is contained within the state given as argument. This method is mostly used for the graphical rendering of a statechart.

Parameters:

state - The state in question

Returns:

A state, or null if no such state exists

add

public Statechart<T> add(State<T> s)

Adds a new state to this statechart

Parameters:

s - The state

Returns:

This statechart

add

public Statechart<T> add(int source,
                         Transition<T> transition)

Adds a new transition to the statechart

Parameters:

source - The ID of the source state

transition - The transition

Returns:

This statechart

add

public Statechart<T> add(java.lang.String source_name,
                         Transition<T> transition)

Adds a new transition to the statechart

Parameters:

source - The name of the source state

transition - The transition

Returns:

This statechart

takeTransition

public Transition<T> takeTransition(T event)

Takes a transition in this statechart with the given event

Parameters:

event - The event

Returns:

The transition that was taken

applyTransition

public boolean applyTransition(T event,
                               Configuration<T> node)

Attempts to apply a transition on this statechart

Parameters:

event - The event to apply

node - The state node

Returns:

true if the transition could be applied, false otherwise

getState

protected State<T> getState(java.lang.String name)

Gets a state with given name

Parameters:

name - The name

Returns:

The state, or null if no state exists with such name

getCurrentConfiguration

public Configuration<T> getCurrentConfiguration()

Gets the identifier of the current state of the statechart. If that state is itself a box containing a statechart, its state is also returned, and so on recursively. Therefore, this method returns a list of state IDs, with the first element being the ID of the top-most state, followed by the ID of the inner state (if any), and so on.

Returns:

The list of state IDs

reset

public Statechart<T> reset()

Resets the statechart to its initial configuration

Returns:

This statechart

clone

public Statechart<T> clone(Statechart<T> parent)

Creates a copy of this statechart

Parameters:

parent - The parent statechart, in case this statechart is enclosed within another. Set to null otherwise

Returns:

A clone of this statechart

getEdgeCount

public int getEdgeCount()

Counts the edges in this statechart

Returns:

The number of edges

getInitialConfiguration

public Configuration<T> getInitialConfiguration()

Gets the initial configuration of this statechart

Returns:

The initial configuration

hasVariable

public boolean hasVariable(java.lang.String var_name)

Checks if a statechart has a variable of given name

Parameters:

var_name - The name of the variable

Returns:

true if the statechart has the variable, false otherwise

getVariable

public java.lang.Object getVariable(java.lang.String var_name)

Gets the value of a state variable

Parameters:

var_name - The name of the variable

Returns:

The value, or null if the variable is not defined in this statechart

findOwner

public static Statechart<?> findOwner(Statechart<?> statechart,
                                      java.lang.String var_name)

Finds the statechart instance that "owns" the state variable of given name. The method starts from a statechart, and if the variable is not defined, moves up to its parent, and so on.

Parameters:

statechart - The statechart used as a starting point for the search.

var_name - The name of the variable

Returns:

The statechart where this variable is defined, or null if the variable could not be found in this statechart, nor any of its parents

findOwner

public Statechart<?> findOwner(java.lang.String var_name)

Finds the statechart instance that "owns" the state variable of given name. The method starts from a statechart, and if the variable is not defined, moves up to its parent, and so on.

Parameters:

var_name - The name of the variable

Returns:

The statechart where this variable is defined, or null if the variable could not be found in this statechart, nor any of its parents

getTransitions

public java.util.Map<java.lang.Integer,java.util.Set<Transition<T>>> getTransitions()

Returns:

the m_transitions

setTransitions

public void setTransitions(java.util.Map<java.lang.Integer,java.util.Set<Transition<T>>> m_transitions)

Parameters:

m_transitions - the m_transitions to set

getStates

public java.util.Map<java.lang.String,State<T>> getStates()

Gets the states of this statechart

Returns:

A map whose keys are state names, and whose values are the corresponding state objects

putAllStateVariables

protected void putAllStateVariables(Statechart<T> sc)

getInitialState

public State<T> getInitialState()

Gets the initial state of this statechart

Returns:

The initial state