Package org.jacop.constraints

Class ElementVariable

  • All Implemented Interfaces:
    SatisfiedPresent, Stateful, UsesQueueVariable
    public class ElementVariable
extends Constraint
implements UsesQueueVariable, Stateful, SatisfiedPresent
    ElementVariable 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:
    4.8

    • Field Detail

      • idNumber

        static java.util.concurrent.atomic.AtomicInteger idNumber

      • firstConsistencyCheck

        boolean firstConsistencyCheck

      • firstConsistencyLevel

        int firstConsistencyLevel

      • 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 IntVar[] 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.

      • indexHasChanged

        boolean indexHasChanged

      • variableQueue

        java.util.LinkedHashSet<IntVar> variableQueue

      • mapping

        java.util.Map<IntVar,​java.lang.Integer> mapping

      • duplicates

        java.util.Map<IntVar,​java.util.List<java.lang.Integer>> duplicates

      • valueHasChanged

        private boolean valueHasChanged

      • generator

        java.util.Random generator

    • Constructor Detail

      • ElementVariable

        public ElementVariable​(IntVar index,
                       IntVar[] list,
                       IntVar value,
                       int indexOffset)
        It constructs an element constraint.
        Parameters:
        index - variable index
        list - list of variables from which an index-th element is taken
        value - a value of the index-th element from list
        indexOffset - shift applied to index variable.

      • ElementVariable

        public ElementVariable​(IntVar index,
                       java.util.List<? extends IntVar> list,
                       IntVar value)
        It constructs an element constraint.
        Parameters:
        index - variable index
        list - list of variables from which an index-th element is taken
        value - a value of the index-th element from list

      • ElementVariable

        public ElementVariable​(IntVar index,
                       java.util.List<? extends IntVar> list,
                       IntVar value,
                       int indexOffset)
        It constructs an element constraint.
        Parameters:
        index - variable index
        list - list of variables from which an index-th element is taken
        value - a value of the index-th element from list
        indexOffset - shift applied to index variable.

      • ElementVariable

        public ElementVariable​(IntVar index,
                       IntVar[] list,
                       IntVar value)
        It constructs an element constraint.
        Parameters:
        index - variable index
        list - list of variables from which an index-th element is taken
        value - a value of the index-th element from list

    • Method Detail

      • 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.

      • 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.

      • 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 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.

      • satisfied

        public boolean satisfied()
        Description copied from interface: SatisfiedPresent
        It checks if the constraint is satisfied. It can return false even if constraint is satisfied but not all variables in its scope are grounded. It needs to return true if all variables in its scope are grounded and constraint is satisfied.

        Implementations of this interface for constraints that are not PrimitiveConstraint may require constraint imposition and consistency check as a requirement to work correctly.

        Specified by:
        satisfied in interface SatisfiedPresent
        Returns:
        true if constraint is possible to verify that it is satisfied.

      • toString

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