Package org.jacop.constraints

Class Constraint

    • Field Detail

      • trace

        public boolean trace

      • numberId

        public int numberId
        It specifies the number id for a given constraint. All constraints within the same type have unique number ids.

      • scope

        protected java.util.Set<Var> scope
        It specifies a set of variables that in the scope of this constraint.

      • watchedVariableGrounded

        Var watchedVariableGrounded

      • increaseWeight

        public boolean increaseWeight
        It specifies if upon the failure of the constraint, all variables in the constraint scope should have their weight increased.

      • consistencyPruningEvents

        public java.util.Hashtable<Var,​java.lang.Integer> consistencyPruningEvents
        It specifies the event which must occur in order for the consistency function to be called.

      • earlyTerminationOK

        public boolean earlyTerminationOK
        It specifies if the constraint consistency function can be prematurely terminated through other than FailureException exception.

      • atomicExecution

        public boolean atomicExecution
        It specifies if the constraint consistency function requires consistency function executed in one atomic step. A constraint can specify that if any other pruning events are initiated by outside entity then the constraint may not work correctly if the execution is continued, but it will work well if consistency() function is restarted.

      • afcWeight

        float afcWeight
        Handling of AFC (accumulated failure fail) for constraints

    • Constructor Detail

      • Constraint

        protected Constraint()

      • Constraint

        protected Constraint​(Var[]... vars)

      • Constraint

        protected Constraint​(java.util.stream.Stream<Var> vars)

      • Constraint

        protected Constraint​(java.util.Set<? extends Var> set)

    • Method Detail

      • arguments

        public java.util.Set<Var> arguments()
        It returns the variables in a scope of the constraint.
        Returns:
        variables in a scope of the constraint.

      • setScope

        protected void setScope​(Var... variables)

      • setScope

        protected void setScope​(Var[]... variables)

      • setScope

        protected void setScope​(java.util.stream.Stream<Var> scope)

      • setScope

        protected void setScope​(java.util.Set<? extends Var> set)

      • setConstraintScope

        protected void setConstraintScope​(PrimitiveConstraint... primitiveConstraints)

      • consistency

        public abstract void consistency​(Store store)
        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.
        Parameters:
        store - constraint store within which the constraint consistency is being checked.

      • getConsistencyPruningEvent

        public int getConsistencyPruningEvent​(Var var)
        It retrieves the pruning event which causes reevaluation of the 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 abstract int getDefaultConsistencyPruningEvent()

      • id

        public java.lang.String id()
        It gives the id string of a constraint.
        Returns:
        string id of the constraint.

      • impose

        public void impose​(Store store)
        It imposes the constraint in a given store.
        Parameters:
        store - the constraint store to which the constraint is imposed to.

      • impose

        public void impose​(Store store,
                   int queueIndex)
        It imposes the constraint and adjusts the queue index.
        Parameters:
        store - the constraint store to which the constraint is imposed to.
        queueIndex - the index of the queue in the store it is assigned to.

      • queueVariable

        public void queueVariable​(int level,
                          Var var)
        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.
        Parameters:
        level - the level of the store at which the change has occurred.
        var - variable which has changed.

      • removeConstraint

        public void removeConstraint()
        It removes the constraint by removing this constraint from all variables.

      • setWatchedVariableGrounded

        public void setWatchedVariableGrounded​(Var var)

      • watchedVariableGrounded

        public boolean watchedVariableGrounded()

      • grounded

        public boolean grounded()
        It checks if the constraint has all variables in its scope grounded (singletons).
        Returns:
        true if all variables in constraint scope are singletons, false otherwise.

      • grounded

        public boolean grounded​(Var[] vars)
        It checks if provided variables are grounded (singletons).
        Parameters:
        vars - variables to be checked if they are grounded.
        Returns:
        true if all variables in constraint scope are singletons, false otherwise.

      • toString

        public java.lang.String toString()
        It produces a string representation of a constraint state.
        Overrides:
        toString in class java.lang.Object

      • intArrayToString

        public static java.lang.String intArrayToString​(int[] array)

      • getGuideConstraint

        public Constraint getGuideConstraint()
        It specifies a constraint which if imposed by search will enhance propagation of this constraint.
        Returns:
        Constraint enhancing propagation of this constraint.

      • getGuideVariable

        public Var getGuideVariable()
        This function provides a variable which assigned a value returned by will enhance propagation of this constraint.
        Returns:
        Variable which is a base of enhancing constraint.

      • getGuideValue

        public int getGuideValue()
        This function provides a value which if assigned to a variable returned by getGuideVariable() will enhance propagation of this constraint.
        Returns:
        Value which is a base of enhancing constraint.

      • supplyGuideFeedback

        public void supplyGuideFeedback​(boolean feedback)
        This function allows to provide a guide feedback. If constraint does not propose sufficiently good enhancing constraints it will be informed so it has a chance to reexamine its efforts.
        Parameters:
        feedback - true if the guide was useful, false otherwise.

      • increaseWeight

        public void increaseWeight()
        It increases the weight of the variables in the constraint scope.

      • setConsistencyPruningEvent

        public void setConsistencyPruningEvent​(Var var,
                                       int pruningEvent)
        It allows to customize the event for a given variable which causes the re-execution of the consistency method for a constraint.
        Parameters:
        var - variable for which the events are customized.
        pruningEvent - the event which must occur to trigger execution of the consistency method.

      • numberArgs

        public int numberArgs()
        It returns the number of variables within a constraint scope.
        Returns:
        number of variables in the constraint scope.

      • requiresMonotonicity

        public boolean requiresMonotonicity()
        It specifies if the constraint allows domains of variables in its scope only to shrink its domain with the progress of search downwards.
        Returns:
        true, by default by all constraints.

      • imposeDecomposition

        public void imposeDecomposition​(Store store)
        It imposes the decomposition of the given constraint in a given store.
        Specified by:
        imposeDecomposition in class DecomposedConstraint<Constraint>
        Parameters:
        store - the constraint store to which the constraint is imposed to.

      • decompose

        public java.util.List<Constraint> decompose​(Store store)
        It returns an array list of constraint which are used to decompose this constraint. It actually creates a decomposition (possibly also creating variables), but it does not impose the constraint.
        Specified by:
        decompose in class DecomposedConstraint<Constraint>
        Parameters:
        store - the constraint store in which context the decomposition takes place.
        Returns:
        an array list of constraints used to decompose this constraint.

      • afc

        public float afc()

      • updateAFC

        public void updateAFC​(java.util.Set<Constraint> allConstraints,
                      float decay)

      • cleanAfterFailure

        public void cleanAfterFailure()
        It is executed after the constraint has failed. It allows to clean some data structures.

      • toInt

        static int toInt​(float f)

      • toInt

        static int toInt​(double f)

      • long2int

        int long2int​(long value)