choco
Class AbstractConstraint

java.lang.Object
  choco.AbstractEntity
      choco.AbstractConstraint

All Implemented Interfaces:

Constraint, Entity, VarEventListener, Propagator, java.lang.Cloneable, java.util.EventListener

Direct Known Subclasses:

AbstractBinRealIntConstraint, AbstractCompositeConstraint, AbstractIntConstraint, AbstractLargeRealConstraint, AbstractMixedConstraint, AbstractSetConstraint, AbstractUnRealConstraint, ConstantConstraint

public abstract class AbstractConstraint
extends AbstractEntity
implements Propagator

An abstract class for all implementations of listeners

Field Summary

protected IStateBool	active a field for storing whether the constraint is active or not
protected ConstraintEvent	constAwakeEvent The constraint awake var attached to the constraint.
protected ConstraintPlugin	hook A field for attaching additional data util (useful for PaLM)
protected int	priority The priority of the constraint.

Fields inherited from class choco.AbstractEntity

problem

Constructor Summary

AbstractConstraint()
Constraucts a constraint with the priority 0.

AbstractConstraint(int priority)
Constructs a constraint with the specified priority.

Method Summary

void	addListener(boolean dynamicAddition) This function connects a constraint with its variables in several ways.
void	awake() Default initial propagation: full constraint re-propagation.
void	awakeOnVar(int idx) Default propagation on variable revision: full constraint re-propagation.
java.lang.Object	clone() returns a copy of the constraint.
int	connectVar(AbstractVar v, int j, boolean dynamicAddition)
void	constAwake(boolean isInitialPropagation) Initial propagation of the constraint.
void	delete() Removes a constraint from the network.
void	fail() raise a contradiction during propagation when the constraint can definitely not be satisfied given the current domains
PropagationEvent	getEvent() Returns the constraint awake var attached to the constraint.
ConstraintPlugin	getPlugIn() Returns the constraint plugin.
int	getPriority() Returns the priority.
AbstractProblem	getProblem() Retrieve the problem of the constraint.
int	getVarIdxInOpposite(int i) computes the index of the i-th variable in the counter-opposite of the constraint
boolean	isActive() Checks if the constraint is active (e.g. plays a role in the propagation phase).
java.lang.Boolean	isEntailed() Checks whether the constraint is definitely satisfied, no matter what further restrictions occur to the domain of its variables.
boolean	isEquivalentTo(Constraint compareTo) tests the equivalence (logical equality of the conditions) between two constraints.
AbstractConstraint	opposite() computes the constraint modelling the counter-opposite condition of this
void	setActive() Un-freezing a constraint (this is useful for mimicking dynamic constraint posts...).
void	setEntailed() records that a constraint is now entailed (therefore it is now useless to propagate it again)
void	setPassive() Freezing a constraint (this is useful for backtracking when mimicking dynamic constraint posts...).
void	setPlugIn(ConstraintPlugin hook) Set the ConstraintPlugin of the constraint.
int	substituteVar(Var oldvar, Var newvar) substitues all occurrences of a variable in a constraint by another variable

Methods inherited from class choco.AbstractEntity

pretty

Methods inherited from class java.lang.Object

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

Methods inherited from interface choco.Propagator

assignIndices, isCompletelyInstantiated, isConsistent, propagate

Methods inherited from interface choco.Constraint

getConstraintIdx, getNbVars, getVar, isSatisfied, setConstraintIndex, setVar

Methods inherited from interface choco.Entity

pretty

Field Detail

priority

protected int priority

The priority of the constraint.

constAwakeEvent

protected ConstraintEvent constAwakeEvent

The constraint awake var attached to the constraint.

hook

protected ConstraintPlugin hook

A field for attaching additional data util (useful for PaLM)

active

protected IStateBool active

a field for storing whether the constraint is active or not

Constructor Detail

AbstractConstraint

public AbstractConstraint()

Constraucts a constraint with the priority 0.

AbstractConstraint

public AbstractConstraint(int priority)

Constructs a constraint with the specified priority.

Parameters:

priority - The wished priority.

Method Detail

getPlugIn

public ConstraintPlugin getPlugIn()

Returns the constraint plugin. Useful for extending the solver.

Specified by:

getPlugIn in interface Propagator

setPlugIn

public void setPlugIn(ConstraintPlugin hook)

Set the ConstraintPlugin of the constraint. The constraint plugin gives access to the dependency net of each constraint, it can be useful to design search heuristic based on explanation.

Parameters:

hook -

getEvent

public PropagationEvent getEvent()

Returns the constraint awake var attached to the constraint.

Specified by:

getEvent in interface Propagator

constAwake

public void constAwake(boolean isInitialPropagation)

Initial propagation of the constraint.

Specified by:

constAwake in interface Propagator

getPriority

public int getPriority()

Returns the priority.

Specified by:

getPriority in interface Propagator

awakeOnVar

public void awakeOnVar(int idx)
                throws ContradictionException

Default propagation on variable revision: full constraint re-propagation.

Specified by:

awakeOnVar in interface VarEventListener

Specified by:

awakeOnVar in interface Propagator

Throws:

ContradictionException

awake

public void awake()
           throws ContradictionException

Default initial propagation: full constraint re-propagation.

Specified by:

awake in interface Propagator

Throws:

ContradictionException

getProblem

public AbstractProblem getProblem()

Retrieve the problem of the constraint.

Specified by:

getProblem in interface Entity

Overrides:

getProblem in class AbstractEntity

setActive

public void setActive()

Un-freezing a constraint (this is useful for mimicking dynamic constraint posts...).

Specified by:

setActive in interface VarEventListener

setPassive

public void setPassive()

Freezing a constraint (this is useful for backtracking when mimicking dynamic constraint posts...).

Specified by:

setPassive in interface VarEventListener

setEntailed

public void setEntailed()

records that a constraint is now entailed (therefore it is now useless to propagate it again)

delete

public void delete()

Removes a constraint from the network. Beware, this is a permanent removal, it may not be backtracked

Specified by:

delete in interface Propagator

fail

public void fail()
          throws ContradictionException

raise a contradiction during propagation when the constraint can definitely not be satisfied given the current domains

Throws:

ContradictionException

isEntailed

public java.lang.Boolean isEntailed()

Description copied from interface: Propagator

Checks whether the constraint is definitely satisfied, no matter what further restrictions occur to the domain of its variables.

Specified by:

isEntailed in interface Propagator

isActive

public boolean isActive()

Checks if the constraint is active (e.g. plays a role in the propagation phase).

Specified by:

isActive in interface VarEventListener

Returns:

true if the constraint is indeed currently active

addListener

public void addListener(boolean dynamicAddition)

This function connects a constraint with its variables in several ways. Note that it may only be called once the constraint has been fully created and is being posted to a problem. Note that it should be called only once per constraint. This can be a dynamic addition (undone upon backtracking) or not

Specified by:

addListener in interface VarEventListener

getVarIdxInOpposite

public int getVarIdxInOpposite(int i)

Description copied from interface: Constraint

computes the index of the i-th variable in the counter-opposite of the constraint

Specified by:

getVarIdxInOpposite in interface Constraint

Parameters:

i - the index of the variable in the current constraint (this)

Returns:

the index of the variable in the opposite constraint (this.opposite())

opposite

public AbstractConstraint opposite()

Description copied from interface: Constraint

computes the constraint modelling the counter-opposite condition of this

Specified by:

opposite in interface Constraint

Returns:

a new constraint (modelling the opposite condition)

connectVar

public int connectVar(AbstractVar v,
                      int j,
                      boolean dynamicAddition)

isEquivalentTo

public boolean isEquivalentTo(Constraint compareTo)

Description copied from interface: Constraint

tests the equivalence (logical equality of the conditions) between two constraints. In particular whenever c1.equals(c2), then c1.isEquivalent(c2).

Specified by:

isEquivalentTo in interface Constraint

Parameters:

compareTo - the constraint to be compared to

Returns:

true if and only if the constraints model the same logical condition.

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Description copied from interface: Constraint

returns a copy of the constraint. This copy is a new object, may be a recursive copy in case of composite constraints. The original and the copy share the same variables & plugins

Specified by:

clone in interface Constraint

Overrides:

clone in class java.lang.Object

Returns:

Throws:

java.lang.CloneNotSupportedException

substituteVar

public int substituteVar(Var oldvar,
                         Var newvar)

substitues all occurrences of a variable in a constraint by another variable

Parameters:

oldvar - the variable to be removed

newvar - the variable to be introduced in place of the other

Returns:

the number of occurrences that have been substituted