org.cpsolver.coursett.constraint

Class MaxBreaksFlexibleConstraint

java.lang.Object

org.cpsolver.ifs.model.Constraint<V,T>

org.cpsolver.ifs.assignment.context.ConstraintWithContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>

org.cpsolver.coursett.constraint.FlexibleConstraint

org.cpsolver.coursett.constraint.MaxBreaksFlexibleConstraint

All Implemented Interfaces:

Comparable<Constraint<Lecture,Placement>>, CanHoldContext, HasAssignmentContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>, WeakeningConstraint<Lecture,Placement>

public class MaxBreaksFlexibleConstraint
extends FlexibleConstraint
implements WeakeningConstraint<Lecture,Placement>

The MaxBreaks constraint limits the number of blocks of non back-to-back classes of an instructor on a day.
It has two parameters: a maximal number of breaks and a minimal length of a break between two classes not to be considered in the same block.
Reference _MaxBreaks:1:30_ translates to a maximum number of one break (two blocks) on a day of classes not more than 30 minutes a part.

Version:

CourseTT 1.3 (University Course Timetabling)
Copyright (C) 2013 - 2014 Tomáš Müller

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 3 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 see http://www.gnu.org/licenses/.

Author:

Tomáš Müller

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	MaxBreaksFlexibleConstraint.MaxBreaksFlexibleConstraintContext

Nested classes/interfaces inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

FlexibleConstraint.Block, FlexibleConstraint.FlexibleConstraintContext, FlexibleConstraint.FlexibleConstraintType, FlexibleConstraint.PlacementTimeComparator

Field Summary

Fields

Modifier and Type	Field and Description
protected int	iMaxBlocksOnADay

Fields inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

iConstraintType, iDayOfWeekOffset, iPreciseDateComputation, iPreference, iReference, iWeeks

Fields inherited from class org.cpsolver.ifs.model.Constraint

iConstraintListeners, iId

Fields inherited from interface org.cpsolver.ifs.assignment.context.CanHoldContext

sMaxSize

Constructor Summary

Constructors

Constructor and Description
MaxBreaksFlexibleConstraint(Long id, String owner, String preference, String reference)

Method Summary

Modifier and Type	Method and Description
void	computeConflicts(Assignment<Lecture,Placement> assignment, Placement value, Set<Placement> conflicts) The only method which has to be implemented by any constraint.
FlexibleConstraint.FlexibleConstraintContext	createAssignmentContext(Assignment<Lecture,Placement> assignment) Create a new assignment context for the given assignment.
List<FlexibleConstraint.Block>	getBlocks(Assignment<Lecture,Placement> assignment, int dayCode, Set<Placement> conflicts, Placement value, HashMap<Lecture,Placement> assignments, BitSet week)
double	getNrViolations(Assignment<Lecture,Placement> assignment, Set<Placement> conflicts, HashMap<Lecture,Placement> assignments) Return current number of violations.
void	weaken(Assignment<Lecture,Placement> assignment) Weaken the constraint.
void	weaken(Assignment<Lecture,Placement> assignment, Placement value) Weaken the constraint enough so that it can assign the given value.

Methods inherited from class org.cpsolver.coursett.constraint.FlexibleConstraint

getCurrentPreference, getDayOfWeekOffset, getName, getOwner, getPrologPreference, getReference, getRelevantPlacements, getType, getWeeks, isConsistent, isHard, isPreciseDateComputation, mergeToBlocks, shareWeeksAndDay, toString

Methods inherited from class org.cpsolver.ifs.assignment.context.ConstraintWithContext

assigned, getAssignmentContextReference, getContext, getContext, setAssignmentContextReference, setModel, unassigned

Methods inherited from class org.cpsolver.ifs.model.Constraint

addConstraintListener, addVariable, assignedVariables, compareTo, computeConflictsNoForwardCheck, constraintListeners, countAssignedVariables, countVariables, equals, getDescription, getId, getModel, hashCode, inConflict, removeConstraintListener, removeVariable, variables

Methods inherited from class java.lang.Object

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

Field Detail

iMaxBlocksOnADay

protected int iMaxBlocksOnADay

Constructor Detail

MaxBreaksFlexibleConstraint

public MaxBreaksFlexibleConstraint(Long id,
                                   String owner,
                                   String preference,
                                   String reference)

Method Detail

getBlocks

public List<FlexibleConstraint.Block> getBlocks(Assignment<Lecture,Placement> assignment,
                                                int dayCode,
                                                Set<Placement> conflicts,
                                                Placement value,
                                                HashMap<Lecture,Placement> assignments,
                                                BitSet week)

getNrViolations

public double getNrViolations(Assignment<Lecture,Placement> assignment,
                              Set<Placement> conflicts,
                              HashMap<Lecture,Placement> assignments)

Description copied from class: FlexibleConstraint

Return current number of violations.

Specified by:

getNrViolations in class FlexibleConstraint

Parameters:

assignment - current assignment

conflicts - conflicting placements to be unassigned

assignments - assigned placements

Returns:

the number of violations of the constraint during days and all weeks of the semester

computeConflicts

public void computeConflicts(Assignment<Lecture,Placement> assignment,
                             Placement value,
                             Set<Placement> conflicts)

Description copied from class: Constraint

The only method which has to be implemented by any constraint. It returns the values which needs to be unassigned in order to make this constraint consistent with the given value if it is assigned to its variable. The computed list of conflicting values is added to the given set of conflicts.

Specified by:

computeConflicts in class Constraint<Lecture,Placement>

Parameters:

assignment - current assignment

value - value to be assigned to its variable

conflicts - resultant set of conflicting values

weaken

public void weaken(Assignment<Lecture,Placement> assignment)

Description copied from interface: WeakeningConstraint

Weaken the constraint. This method is called if the constraint participates in an unassigned of a variable.

Specified by:

weaken in interface WeakeningConstraint<Lecture,Placement>

Parameters:

assignment - current assignment

weaken

public void weaken(Assignment<Lecture,Placement> assignment,
                   Placement value)

Description copied from interface: WeakeningConstraint

Weaken the constraint enough so that it can assign the given value.

Specified by:

weaken in interface WeakeningConstraint<Lecture,Placement>

Parameters:

assignment - current assignment

value - a conflicting value to be assigned

createAssignmentContext

public FlexibleConstraint.FlexibleConstraintContext createAssignmentContext(Assignment<Lecture,Placement> assignment)

Description copied from interface: HasAssignmentContext

Create a new assignment context for the given assignment. If there are already some variables assigned in the value, the method should make sure that the context is appropriately initialized.

Specified by:

createAssignmentContext in interface HasAssignmentContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>

Overrides:

createAssignmentContext in class FlexibleConstraint

Parameters:

assignment - an assignment for which there needs to be an assignment context

Returns:

a new instance of the assignment context, filled according to the given assignment