org.cpsolver.coursett.constraint

Class FlexibleConstraint

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

All Implemented Interfaces:

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

Direct Known Subclasses:

BreakFlexibleConstraint, MaxBlockFlexibleConstraint, MaxBreaksFlexibleConstraint, MaxConsecutiveDaysFlexibleConstraint, MaxDaysFlexibleConstraint, MaxHalfDaysFlexibleConstraint, MaxHolesFlexibleConstraint, MaxWeeksFlexibleConstraint

public abstract class FlexibleConstraint
extends ConstraintWithContext<Lecture,Placement,FlexibleConstraint.FlexibleConstraintContext>

Flexible constraint.
This constraint expresses relations between several classes. Provides similar functions as Group constraint. Unlike group constraint, Flexible constraint is able to parse some of its parameters from its reference field

Version:

CourseTT 1.3 (University Course Timetabling)
Copyright (C) 2013 Matej Lukac

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:

Matej Lukac

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	FlexibleConstraint.Block A block is a list of placements sorted by startSlot, which are BTB.
class	FlexibleConstraint.FlexibleConstraintContext
static class	FlexibleConstraint.FlexibleConstraintType Flexible constraint types
protected static class	FlexibleConstraint.PlacementTimeComparator Placement comparator: earlier placement first, shorter placement first if both start at the same time.

Field Summary

Fields

Modifier and Type	Field and Description
protected FlexibleConstraint.FlexibleConstraintType	iConstraintType
protected Integer	iDayOfWeekOffset
protected Boolean	iPreciseDateComputation
protected int	iPreference
protected String	iReference
protected List<BitSet>	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
FlexibleConstraint(Long id, String owner, String preference, String reference) Constructor

Method Summary

Modifier and Type	Method and Description
FlexibleConstraint.FlexibleConstraintContext	createAssignmentContext(Assignment<Lecture,Placement> assignment) Create a new assignment context for the given assignment.
double	getCurrentPreference(Assignment<Lecture,Placement> assignment, Set<Placement> conflicts, HashMap<Lecture,Placement> assignments) Return the current preference of the flexible constraint, considering conflicts and new assignments.
int	getDayOfWeekOffset()
String	getName() Constraint's name -- for printing purposes
abstract double	getNrViolations(Assignment<Lecture,Placement> assignment, Set<Placement> conflicts, HashMap<Lecture,Placement> assignments) Return current number of violations.
String	getOwner()
String	getPrologPreference() Prolog reference: "R" for required, "P" for prohibited", "-2",.."2" for preference
String	getReference()
protected Set<Placement>	getRelevantPlacements(Assignment<Lecture,Placement> assignment, int dayCode, Set<Placement> conflicts, Placement value, HashMap<Lecture,Placement> assignments, BitSet week) Returns placements of variables assigned to this constraint with assignment which satisfy following conditions: They must be taught in the day included in dayCode.
FlexibleConstraint.FlexibleConstraintType	getType()
List<BitSet>	getWeeks() Return weeks of the term.
boolean	isConsistent(Placement value1, Placement value2) Returns true if the given assignments are consistent respecting this constraint.
boolean	isHard() Returns true if the constraint is hard.
boolean	isPreciseDateComputation()
protected List<FlexibleConstraint.Block>	mergeToBlocks(List<Placement> sorted, int maxBreakBetweenBTB) Creates a list of blocks from a placements sorted by startSlot
protected boolean	shareWeeksAndDay(TimeLocation t, BitSet week, int dayCode) Used to determine the daycode and week of a timelocation
String	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, computeConflicts, 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

iPreference

protected int iPreference

iConstraintType

protected FlexibleConstraint.FlexibleConstraintType iConstraintType

iReference

protected String iReference

iWeeks

protected List<BitSet> iWeeks

iDayOfWeekOffset

protected Integer iDayOfWeekOffset

iPreciseDateComputation

protected Boolean iPreciseDateComputation

Constructor Detail

FlexibleConstraint

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

Constructor

Parameters:

id - unique id

owner - identifier of distribution preference the constraint was created for

preference - time preference ("R" for required, "P" for prohibited, "-2", "-1", "1", "2" for soft preference)

reference - parameters of the constraint in String form

Method Detail

getNrViolations

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

Return current number of violations.

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

getWeeks

public List<BitSet> getWeeks()

Return weeks of the term.

Returns:

a list of bitsets (one for each week of the term) representing datePatterns or null if semester is whole semester is considered

getDayOfWeekOffset

public int getDayOfWeekOffset()

isPreciseDateComputation

public boolean isPreciseDateComputation()

isConsistent

public boolean isConsistent(Placement value1,
                            Placement value2)

Description copied from class: Constraint

Returns true if the given assignments are consistent respecting this constraint. This method is used by MAC (see MacPropagation).

Overrides:

isConsistent in class Constraint<Lecture,Placement>

Parameters:

value1 - a value

value2 - a value

Returns:

true if the constraint is ok with the assignment

getRelevantPlacements

protected Set<Placement> getRelevantPlacements(Assignment<Lecture,Placement> assignment,
                                               int dayCode,
                                               Set<Placement> conflicts,
                                               Placement value,
                                               HashMap<Lecture,Placement> assignments,
                                               BitSet week)

Returns placements of variables assigned to this constraint with assignment which satisfy following conditions: They must be taught in the day included in dayCode. They cannot be included in conflicts Their date pattern intersects with week

Parameters:

assignment - current assignment

dayCode - representation of days in week combination

conflicts - placements to be unassigned

value - placement to be assigned

assignments - placements of variables

week - bitset representing a date pattern

Returns:

placements of variables assigned to this constraint with assignment which satisfy conditions above

shareWeeksAndDay

protected boolean shareWeeksAndDay(TimeLocation t,
                                   BitSet week,
                                   int dayCode)

Used to determine the daycode and week of a timelocation

Parameters:

t - timelocation

week - date pattern compared to timelocation

dayCode - days compared to timelocation

Returns:

true if TimeLocation matches the date pattern and days

mergeToBlocks

protected List<FlexibleConstraint.Block> mergeToBlocks(List<Placement> sorted,
                                                       int maxBreakBetweenBTB)

Creates a list of blocks from a placements sorted by startSlot

Parameters:

sorted - list of placements sorted by startSlot

maxBreakBetweenBTB - maximum number of free slots between BTB placements

Returns:

groups of BTB placements as a list of blocks

isHard

public boolean isHard()

Description copied from class: Constraint

Returns true if the constraint is hard. Only hard constraints are allowed to unassign a variable when there is a conflict with a value that is being assigned

Overrides:

isHard in class Constraint<Lecture,Placement>

Returns:

true if the constraint is hard

getName

public String getName()

Description copied from class: Constraint

Constraint's name -- for printing purposes

Overrides:

getName in class Constraint<Lecture,Placement>

Returns:

constraint name

getType

public FlexibleConstraint.FlexibleConstraintType getType()

getReference

public String getReference()

getOwner

public String getOwner()

getPrologPreference

public String getPrologPreference()

Prolog reference: "R" for required, "P" for prohibited", "-2",.."2" for preference

Returns:

prolog preference

getCurrentPreference

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

Return the current preference of the flexible constraint, considering conflicts and new assignments. Used to compute value for flexible constraint criterion.

Parameters:

assignment - current assignment

conflicts - conflicting assignment

assignments - proposed assignments

Returns:

the current preference of the flexible constraint

toString

public String toString()

Overrides:

toString in class Object

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.

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