Package org.jacop.constraints

Class ElementInteger

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

    • Field Detail

      • idNumber

        static java.util.concurrent.atomic.AtomicInteger idNumber

      • firstConsistencyCheck

        boolean firstConsistencyCheck

      • firstConsistencyLevel

        int firstConsistencyLevel

      • limitForDomainPruning

        static final int limitForDomainPruning
        It specifies the maximal size of index domain when the constraint will apply domain consistency for value. Otherwise bound consistency is applied. This limit applies to both duplicates and index.
        See Also:
        Constant Field Values

      • minDuplicatesSize

        static final int minDuplicatesSize
        It specifies the minimal size of number of duplicated values on the list that are consodered together.. Otherwise they are processed one by one.
        See Also:
        Constant Field Values

      • 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.

      • checkDuplicates

        public final boolean checkDuplicates
        It specifies whether duplicate values should be treated specially (combined to a single check). In general a good idea but when lists are long it makes the process slower instead of faster.

      • 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.

      • indexHasChanged

        boolean indexHasChanged
        It specifies for each value what are the possible values of the index variable (it takes into account indexOffset.

      • valueHasChanged

        boolean valueHasChanged

      • duplicates

        java.util.List<IntDomain> duplicates
        It holds information about the positions within list array that are equal. It allows to safely skip duplicates when enumerating index domain. duplicatesIndexes is a domain having indexes of all indexes for duplicates.

      • duplicatesIndexes

        IntDomain duplicatesIndexes

    • 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,
                      int[] list,
                      IntVar value,
                      int indexOffset,
                      boolean checkDuplicates)
        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.
        checkDuplicates - informs whether to create duplicates list for values from list (default = true).

      • ElementInteger

        public ElementInteger​(IntVar index,
                      java.util.List<java.lang.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,
                      java.util.List<java.lang.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.

      • ElementInteger

        public ElementInteger​(IntVar index,
                      java.util.List<java.lang.Integer> list,
                      IntVar value,
                      int indexOffset,
                      boolean checkDuplicates)
        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.
        checkDuplicates - informs whether to create duplicates list for values from list (default = true).

      • ElementInteger

        ElementInteger​(IntVar index,
               int[] list,
               IntVar value)
        It constructs an element constraint with indexOffset by default set to 0.
        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

    • 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.

      • disjoint

        boolean disjoint​(IntDomain v1,
                 int v2)

      • isStateful

        public boolean isStateful()
        Description copied from interface: Stateful
        This function can be overriden by any constraint to specify dynamic conditions (based on the domain of variables at imposition level to decide if it is a stateful constraint.
        Specified by:
        isStateful in interface Stateful
        Returns:
        true if constraint is stateful.

      • impose

        public void impose​(Store store)
        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