ElementVariable (jacop 4.2.0 API)

java.lang.Object
- org.jacop.constraints.DecomposedConstraint
- - org.jacop.constraints.Constraint
  - - org.jacop.constraints.ElementVariable

```
public class ElementVariable
extends Constraint
```
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:

4.2

Author:

Krzysztof Kuchcinski and Radoslaw Szymanek

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.
`IntVar[]`	`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
`ElementVariable(IntVar index, ArrayList<? extends IntVar> list, IntVar value, int indexOffset)` It constructs an element constraint.
`ElementVariable(IntVar index, IntVar[] list, IntVar value, int indexOffset)` It constructs an element constraint.

Method Summary

All Methods Instance Methods Concrete Methods
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 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.
  - 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
  - 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,
                       ArrayList<? 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.
- 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

Class ElementVariable

Field Summary

Fields inherited from class org.jacop.constraints.Constraint

Fields inherited from class org.jacop.constraints.DecomposedConstraint

Constructor Summary

Method Summary

Methods inherited from class org.jacop.constraints.Constraint

Methods inherited from class org.jacop.constraints.DecomposedConstraint

Methods inherited from class java.lang.Object

Field Detail

index

value

indexOffset

list

xmlAttributes

Constructor Detail

ElementVariable

ElementVariable

Method Detail

arguments

removeLevel

consistency

getConsistencyPruningEvent

impose

queueVariable

removeConstraint

satisfied

toString

increaseWeight