Package org.jacop.constraints.netflow

Class NetworkFlow

java.lang.Object

org.jacop.constraints.DecomposedConstraint<Constraint>

org.jacop.constraints.Constraint

org.jacop.constraints.netflow.NetworkFlow

All Implemented Interfaces:

RemoveLevelLate, Stateful, UsesQueueVariable

public class NetworkFlow
extends Constraint
implements UsesQueueVariable, Stateful, RemoveLevelLate

The network flow constraint. Use the NetworkBuilder to create a network and instantiate the network.

Version:

4.10

Field Summary

Fields

Modifier and Type	Field	Description
IntVar	costVariable	The cost variable
boolean	disableQueueVariable	Disables the queue variable function during consistency
private static final boolean	DO_INSTRUMENTATION
(package private) static AtomicInteger	idNumber	Instance counter
final Map<IntVar,VarHandler>	map	The variables and their handlers
final Pruning	network	The network
int	previousLevel
final Set<IntVar>	queue	The set of queued variables
private static final int	QUEUE_INDEX
private static final boolean	SHOW_LEVEL
(package private) Statistics	statistics

Fields inherited from class org.jacop.constraints.Constraint

atomicExecution, consistencyPruningEvents, constraintScope, earlyTerminationOK, increaseWeight, numberId, scope, trace

Fields inherited from class org.jacop.constraints.DecomposedConstraint

queueIndex

Constructor Summary

Constructors

Modifier	Constructor	Description
private	NetworkFlow(List<Node> nodes, List<Arc> arcs, List<VarHandler> flowVariables, IntVar costVariable)	Initialization
	NetworkFlow(NetworkBuilder builder)

Method Summary

Modifier and Type	Method	Description
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.
int	getDefaultConsistencyPruningEvent()
void	impose(Store store)	It imposes the constraint in a given store.
void	queueVariable(int level, Var variable)	Search & Backtracking
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This function is called in case of the backtrack, so a constraint can clear the queue of changed variables which is no longer valid.
void	removeLevelLate(int level)	This function is called in case of the backtrack.
String	toString()	Identifiers
private void	updateGraph()

Methods inherited from class org.jacop.constraints.Constraint

afc, arguments, cleanAfterFailure, decompose, getGuideConstraint, getGuideValue, getGuideVariable, grounded, grounded, id, impose, imposeDecomposition, increaseWeight, intArrayToString, long2int, numberArgs, removeConstraint, requiresMonotonicity, setConsistencyPruningEvent, setConstraintScope, setScope, setScope, setScope, setScope, setScope, setWatchedVariableGrounded, supplyGuideFeedback, updateAFC, watchedVariableGrounded

Methods inherited from class org.jacop.constraints.DecomposedConstraint

auxiliaryVariables, checkInput, checkInput, checkInputForDuplication, checkInputForDuplicationSkipSingletons, checkInputForNullness, checkInputForNullness, checkInputForNullness, derivative, getDubletonsSkipSingletons, imposeDecomposition

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jacop.api.Stateful

isStateful

Field Details

QUEUE_INDEX

private static final int QUEUE_INDEX

See Also:

• Constant Field Values

DO_INSTRUMENTATION

private static final boolean DO_INSTRUMENTATION

See Also:

• Constant Field Values

SHOW_LEVEL

private static final boolean SHOW_LEVEL

See Also:

• Constant Field Values

statistics

Statistics statistics

idNumber

static AtomicInteger idNumber

Instance counter

network

public final Pruning network

The network

costVariable

public IntVar costVariable

The cost variable

map

public final Map<IntVar,VarHandler> map

The variables and their handlers

queue

public final Set<IntVar> queue

The set of queued variables

disableQueueVariable

public boolean disableQueueVariable

Disables the queue variable function during consistency

previousLevel

public int previousLevel

Constructor Details

NetworkFlow

private NetworkFlow(List<Node> nodes,
 List<Arc> arcs,
 List<VarHandler> flowVariables,
 IntVar costVariable)

Initialization

NetworkFlow

public NetworkFlow(NetworkBuilder builder)

Method Details

getConsistencyPruningEvent

public int getConsistencyPruningEvent(Var var)

Description copied from class: Constraint

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

Overrides:

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)

getDefaultConsistencyPruningEvent

public int getDefaultConsistencyPruningEvent()

Specified by:

getDefaultConsistencyPruningEvent in class Constraint

impose

public void impose(Store store)

Description copied from class: Constraint

It imposes the constraint in a given store.

Overrides:

impose in class Constraint

Parameters:

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

queueVariable

public void queueVariable(int level,
 Var variable)

Search & Backtracking

Overrides:

queueVariable in class Constraint

Parameters:

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

variable - variable which has changed.

updateGraph

private void updateGraph()

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.

removeLevel

public void removeLevel(int level)

Description copied from interface: Stateful

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.

Specified by:

removeLevel in interface Stateful

Parameters:

level - the level which is being removed.

removeLevelLate

public void removeLevelLate(int level)

Description copied from interface: RemoveLevelLate

This function is called in case of the backtrack. It is called after all timestamps, variables, mutablevariables have reverted to their values *after* removing the level.

Specified by:

removeLevelLate in interface RemoveLevelLate

Parameters:

level - the level which is being removed.

toString

public String toString()

Identifiers

Overrides:

toString in class Constraint