org.jacop.constraints

Class ElementInteger

java.lang.Object

org.jacop.constraints.DecomposedConstraint

org.jacop.constraints.Constraint

org.jacop.constraints.ElementInteger

public class ElementInteger
extends Constraint

ElementInteger constraint defines a relation list[index - indexOffset] = value. The first element of the list corresponds to index - indexOffset = 1. By default indexOffset is equal 0 so first value within a list corresponds to index equal 1. If index has a domain from 0 to list.length-1 then indexOffset has to be equal -1 to make addressing of list array starting from 1.

Version:

3.1

Author:

Radoslaw Szymanek and Krzysztof Kuchcinski

Field Summary

Fields

Modifier and Type	Field and Description
IntVar	index It specifies variable index within an element constraint list[index-indexOffset] = value.
int	indexOffset It specifies indexOffset within an element constraint list[index-indexOffset] = value.
int[]	list It specifies list of variables within an element constraint list[index-indexOffset] = value.
IntVar	value It specifies variable value within an element constraint list[index-indexOffset] = value.
static String[]	xmlAttributes It specifies the arguments required to be saved by an XML format as well as the constructor being called to recreate an object from an XML format.

Fields inherited from class org.jacop.constraints.Constraint

atomicExecution, consistencyPruningEvents, earlyTerminationOK, id, increaseWeight, numberArgs, numberId, trace

Fields inherited from class org.jacop.constraints.DecomposedConstraint

queueIndex

Constructor Summary

Constructors

Constructor and Description
ElementInteger(IntVar index, ArrayList<Integer> list, IntVar value) It constructs an element constraint with default indexOffset equal 0.
ElementInteger(IntVar index, ArrayList<Integer> list, IntVar value, int indexOffset) It constructs an element constraint.
ElementInteger(IntVar index, int[] list, IntVar value, int indexOffset) It constructs an element constraint.

Method Summary

Modifier and Type	Method and Description
ArrayList<Var>	arguments() It returns the variables in a scope of the constraint.
void	consistency(Store store) It is a (most probably incomplete) consistency function which removes the values from variables domains.
int	getConsistencyPruningEvent(Var var) It retrieves the pruning event which causes reevaluation of the constraint.
void	impose(Store store) It imposes the constraint in a given store.
void	increaseWeight() It increases the weight of the variables in the constraint scope.
void	queueVariable(int level, Var var) This is a function called to indicate which variable in a scope of constraint has changed.
void	removeConstraint() It removes the constraint by removing this constraint from all variables.
void	removeLevel(int level) This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid.
boolean	satisfied() It checks if the constraint is satisfied.
String	toString() It produces a string representation of a constraint state.

Methods inherited from class org.jacop.constraints.Constraint

cleanAfterFailure, decompose, getGuideConstraint, getGuideValue, getGuideVariable, id, impose, imposeDecomposition, numberArgs, removeLevelLate, requiresMonotonicity, setConsistencyPruningEvent, supplyGuideFeedback

Methods inherited from class org.jacop.constraints.DecomposedConstraint

auxiliaryVariables, derivative, imposeDecomposition

Methods inherited from class java.lang.Object

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

Field Detail

index

public IntVar index

It specifies variable index within an element constraint list[index-indexOffset] = value.

value

public IntVar value

It specifies variable value within an element constraint list[index-indexOffset] = value.

indexOffset

public final int indexOffset

It specifies indexOffset within an element constraint list[index-indexOffset] = value.

list

public int[] list

It specifies list of variables within an element constraint list[index-indexOffset] = value. The list is addressed by positive integers (>=1) if indexOffset is equal to 0.

xmlAttributes

public static String[] xmlAttributes

It specifies the arguments required to be saved by an XML format as well as the constructor being called to recreate an object from an XML format.

Constructor Detail

ElementInteger

public ElementInteger(IntVar index,
                      int[] list,
                      IntVar value,
                      int indexOffset)

It constructs an element constraint.

Parameters:

index - variable index

list - list of integers from which an index-th element is taken

value - a value of the index-th element from list

indexOffset - shift applied to index variable.

ElementInteger

public ElementInteger(IntVar index,
                      ArrayList<Integer> list,
                      IntVar value)

It constructs an element constraint with default indexOffset equal 0.

Parameters:

index - index variable.

list - list containing variables which one pointed out by index variable is made equal to value variable.

value - a value variable equal to the specified element from the list.

ElementInteger

public ElementInteger(IntVar index,
                      ArrayList<Integer> list,
                      IntVar value,
                      int indexOffset)

It constructs an element constraint.

Parameters:

index - variable index

list - list of integers from which an index-th element is taken

value - a value of the index-th element from list

indexOffset - shift applied to index variable.

Method Detail

arguments

public ArrayList<Var> arguments()

Description copied from class: Constraint

It returns the variables in a scope of the constraint.

Specified by:

arguments in class Constraint

Returns:

variables in a scope of the constraint.

removeLevel

public void removeLevel(int level)

Description copied from class: Constraint

This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid. This function is called *before* all timestamps, variables, mutablevariables have reverted to their previous value.

Overrides:

removeLevel in class Constraint

Parameters:

level - the level which is being removed.

consistency

public void consistency(Store store)

Description copied from class: Constraint

It is a (most probably incomplete) consistency function which removes the values from variables domains. Only values which do not have any support in a solution space are removed.

Specified by:

consistency in class Constraint

Parameters:

store - constraint store within which the constraint consistency is being checked.

getConsistencyPruningEvent

public int getConsistencyPruningEvent(Var var)

Description copied from class: Constraint

It retrieves the pruning event which causes reevaluation of the constraint.

Specified by:

getConsistencyPruningEvent in class Constraint

Parameters:

var - variable for which pruning event is retrieved

Returns:

it returns the int code of the pruning event (GROUND, BOUND, ANY, NONE)

impose

public void impose(Store store)

Description copied from class: Constraint

It imposes the constraint in a given store.

Specified by:

impose in class Constraint

Parameters:

store - the constraint store to which the constraint is imposed to.

queueVariable

public void queueVariable(int level,
                          Var var)

Description copied from class: Constraint

This is a function called to indicate which variable in a scope of constraint has changed. It also indicates a store level at which the change has occurred.

Overrides:

queueVariable in class Constraint

Parameters:

level - the level of the store at which the change has occurred.

var - variable which has changed.

removeConstraint

public void removeConstraint()

Description copied from class: Constraint

It removes the constraint by removing this constraint from all variables.

Specified by:

removeConstraint in class Constraint

satisfied

public boolean satisfied()

Description copied from class: Constraint

It checks if the constraint is satisfied. If this function is incorrectly implemented a constraint may not be satisfied in a solution.

Specified by:

satisfied in class Constraint

Returns:

true if the constraint is for certain satisfied, false otherwise.

toString

public String toString()

Description copied from class: Constraint

It produces a string representation of a constraint state.

Specified by:

toString in class Constraint

increaseWeight

public void increaseWeight()

Description copied from class: Constraint

It increases the weight of the variables in the constraint scope.

Specified by:

increaseWeight in class Constraint