net.sf.cpsolver.ifs.model
Class Variable

java.lang.Object
  net.sf.cpsolver.ifs.model.Variable

All Implemented Interfaces:

Comparable

Direct Known Subclasses:

Activity, CSPVariable, Exam, Lecture, MultiVariable, Operation, Rectangle, Request

public class Variable
extends Object
implements Comparable

Generic variable.

Besides a domain of values, a variable also contains information about assigned value, the value assigned in the best ever found solution and also the initial value (minimal perturbations problem). It also knows what constraints are associated with this variable and has a unique id.

Version:

IFS 1.1 (Iterative Forward Search)
Copyright (C) 2006 Tomáš Müller
muller@unitime.org
Lazenska 391, 76314 Zlin, Czech Republic

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

See Also:

Value, Model, Solver

Field Summary

protected long	iId
protected Value	iValue Assigned value

Constructor Summary

Variable()
Constructor

Variable(Value initialValue)
Constructor

Method Summary

void	addContstraint(Constraint constraint) Adds a constraint.
void	addVariableListener(VariableListener listener) Adds variable listener
void	assign(long iteration, Value value) Assign value to this variable.
int	compareTo(Object o)
Vector	constraints() Return the list of constraints associated with this variable
Hashtable	constraintVariables() Returns a table of all variables linked with this variable by a constraint.
long	countAssignments() Return how many times was this variable assigned in the past.
boolean	equals(Object o)
Value	getAssignment() Returns current assignment
Value	getBestAssignment() Returns the value from the best ever found soultion.
long	getBestAssignmentIteration() Returns the iteration when the best value was assigned
String	getDescription() Variable's description -- for printing purposes
Object	getExtra() Extra information to which can be used by an extension (see Extension).
long	getId() Unique id
Value	getInitialAssignment() Returns initial assignment
Model	getModel() Model, the variable belong to
String	getName() Variable's name -- for printing purposes
Vector	getVariableListeners() Return variable listeners
Vector	hardConstraints() Return the list of hard constraints associated with this variable
boolean	hasAssignment() Returns true if the variable is assigned
int	hashCode()
boolean	hasInitialAssignment() Returns true if the variable has an initial assignment
boolean	hasValues() True, if the variable's domain is not empty
long	lastAssignmentIteration() Returns the iteration when the variable was assigned for the last time (-1 if never)
long	lastUnassignmentIteration() Returns the iteration when the variable was unassigned for the last time (-1 if never)
void	removeContstraint(Constraint constraint) Removes a constraint.
void	removeInitialValue() Permanently remove the initial value from the variable's domain -- for testing MPP
void	removeValue(long iteration, Value value) Permanently remove a value from variables domain.
void	removeVariableListener(VariableListener listener) Removes variable listener
void	setBestAssignment(Value value) Sets variable's value of the best ever found solution.
void	setExtra(Object object) Extra information to which can be used by an extension (see Extension).
void	setInitialAssignment(Value initialValue) Sets initial assignment
void	setModel(Model model) Set the model to which the variable belongs to
protected void	setValues(Vector values) Sets the domain
Vector	softConstraints() Return the list of soft constraints associated with this variable
String	toString()
void	unassign(long iteration) Unassign value from this variable.
Vector	values() Domain

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

iId

protected long iId

iValue

protected Value iValue

Assigned value

Constructor Detail

Variable

public Variable()

Constructor

Variable

public Variable(Value initialValue)

Constructor

Parameters:

initialValue - initial value (minimal-perturbation problem)

Method Detail

getModel

public Model getModel()

Model, the variable belong to

setModel

public void setModel(Model model)

Set the model to which the variable belongs to

values

public Vector values()

Domain

setValues

protected void setValues(Vector values)

Sets the domain

hasValues

public boolean hasValues()

True, if the variable's domain is not empty

getAssignment

public Value getAssignment()

Returns current assignment

hasAssignment

public boolean hasAssignment()

Returns true if the variable is assigned

getInitialAssignment

public Value getInitialAssignment()

Returns initial assignment

setInitialAssignment

public void setInitialAssignment(Value initialValue)

Sets initial assignment

hasInitialAssignment

public boolean hasInitialAssignment()

Returns true if the variable has an initial assignment

assign

public void assign(long iteration,
                   Value value)

Assign value to this variable. If the variable has already assigned another value, it is unassigned first. Also, all conflicting values are unassigned before the given value is assigned to this variable.

Parameters:

iteration - current iteration

value - the value to be assigned

unassign

public void unassign(long iteration)

Unassign value from this variable.

Parameters:

iteration - current iteration

countAssignments

public long countAssignments()

Return how many times was this variable assigned in the past.

addContstraint

public void addContstraint(Constraint constraint)

Adds a constraint. Called automatically when the constraint is added to the model, i.e., Model.addConstraint(Constraint) is called.

Parameters:

constraint - added constraint

removeContstraint

public void removeContstraint(Constraint constraint)

Removes a constraint. Called automatically when the constraint is removed from the model, i.e., Model.removeConstraint(Constraint) is called.

Parameters:

constraint - added constraint

constraints

public Vector constraints()

Return the list of constraints associated with this variable

hardConstraints

public Vector hardConstraints()

Return the list of hard constraints associated with this variable

softConstraints

public Vector softConstraints()

Return the list of soft constraints associated with this variable

toString

public String toString()

Overrides:

toString in class Object

getId

public long getId()

Unique id

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getName

public String getName()

Variable's name -- for printing purposes

getDescription

public String getDescription()

Variable's description -- for printing purposes

setBestAssignment

public void setBestAssignment(Value value)

Sets variable's value of the best ever found solution. Called when Model.saveBest() is called.

getBestAssignment

public Value getBestAssignment()

Returns the value from the best ever found soultion.

getBestAssignmentIteration

public long getBestAssignmentIteration()

Returns the iteration when the best value was assigned

lastAssignmentIteration

public long lastAssignmentIteration()

Returns the iteration when the variable was assigned for the last time (-1 if never)

lastUnassignmentIteration

public long lastUnassignmentIteration()

Returns the iteration when the variable was unassigned for the last time (-1 if never)

compareTo

public int compareTo(Object o)

Specified by:

compareTo in interface Comparable

equals

public boolean equals(Object o)

Overrides:

equals in class Object

addVariableListener

public void addVariableListener(VariableListener listener)

Adds variable listener

removeVariableListener

public void removeVariableListener(VariableListener listener)

Removes variable listener

getVariableListeners

public Vector getVariableListeners()

Return variable listeners

setExtra

public void setExtra(Object object)

Extra information to which can be used by an extension (see Extension).

getExtra

public Object getExtra()

Extra information to which can be used by an extension (see Extension).

removeValue

public void removeValue(long iteration,
                        Value value)

Permanently remove a value from variables domain.

constraintVariables

public Hashtable constraintVariables()

Returns a table of all variables linked with this variable by a constraint.

Returns:

table (variable, constraint)

removeInitialValue

public void removeInitialValue()

Permanently remove the initial value from the variable's domain -- for testing MPP