JaCoP.search
Class SimpleSelect<T extends Var>

java.lang.Object
  JaCoP.search.SimpleSelect<T>

All Implemented Interfaces:

SelectChoicePoint<T>

Direct Known Subclasses:

SplitSelect

public class SimpleSelect<T extends Var>
extends java.lang.Object
implements SelectChoicePoint<T>

It is simple and customizable selector of decisions (constraints) which will be enforced by search.

Version:

3.1

Author:

Radoslaw Szymanek and Krzysztof Kuchcinski

Field Summary

boolean	inputOrderTieBreaking It chooses if input order tie breaking is used.
java.util.IdentityHashMap<T,java.lang.Integer>	position It stores the original positions of variables to be used for input order tie-breaking.

Constructor Summary

SimpleSelect(T[] variables, ComparatorVariable<T> varSelect, ComparatorVariable<T> tieBreakerVarSelect, Indomain<T> indomain)
It constructs a simple selection mechanism for choice points.

SimpleSelect(T[] variables, ComparatorVariable<T> varSelect, Indomain<T> indomain)
The constructor to create a simple choice select mechanism.

Method Summary

PrimitiveConstraint	getChoiceConstraint(int index) It always returns null as choice point is obtained by getChoiceVariable and getChoiceValue.
int	getChoiceValue() It returns a value which is the base of the next choice point.
T	getChoiceVariable(int index) It returns the variable which is the base on the next choice point.
int	getIndex() It returns the current index.
java.util.IdentityHashMap<T,java.lang.Integer>	getVariablesMapping() It returns the variables for which assignment in the solution is given.
T	placeSearchVariable(int searchPosition, int variablePosition) It gets as input the index of the variable which is chosen by search to be instantiated at this stage.
java.lang.String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

inputOrderTieBreaking

public boolean inputOrderTieBreaking

It chooses if input order tie breaking is used.

position

public java.util.IdentityHashMap<T extends Var,java.lang.Integer> position

It stores the original positions of variables to be used for input order tie-breaking.

Constructor Detail

SimpleSelect

public SimpleSelect(T[] variables,
                    ComparatorVariable<T> varSelect,
                    Indomain<T> indomain)

The constructor to create a simple choice select mechanism.

Parameters:

variables - variables upon which the choice points are created.

varSelect - the variable comparator to choose the variable.

indomain - the value heuristic to choose a value for a given variable.

SimpleSelect

public SimpleSelect(T[] variables,
                    ComparatorVariable<T> varSelect,
                    ComparatorVariable<T> tieBreakerVarSelect,
                    Indomain<T> indomain)

It constructs a simple selection mechanism for choice points.

Parameters:

variables - variables used as basis of the choice point.

varSelect - the main variable comparator.

tieBreakerVarSelect - secondary variable comparator employed if the first one gives the same metric.

indomain - the heuristic to choose value assigned to a chosen variable.

Method Detail

getChoiceVariable

public T getChoiceVariable(int index)

It returns the variable which is the base on the next choice point. Only if choice is of an X = C type. This function returns null if all variables have a value assigned or a choice point based on other type of constraint is being selected. The parameter index is the last value which have been return by this SelectChoicePoint object which has not been backtracked upon yet.

Specified by:

getChoiceVariable in interface SelectChoicePoint<T extends Var>

Parameters:

index - the position of the last variable in selection choice point heuristic.

Returns:

variable based on which the choice needs to be created.

getChoiceValue

public int getChoiceValue()

It returns a value which is the base of the next choice point. Only if choice is of an X = C type.

Specified by:

getChoiceValue in interface SelectChoicePoint<T extends Var>

Returns:

value used in the choice point (value).

getChoiceConstraint

public PrimitiveConstraint getChoiceConstraint(int index)

It always returns null as choice point is obtained by getChoiceVariable and getChoiceValue.

Specified by:

getChoiceConstraint in interface SelectChoicePoint<T extends Var>

Parameters:

index - the position of the last variable returned by selection choice point heuristic.

Returns:

primitive constraint which is a base of a choice point.

getVariablesMapping

public java.util.IdentityHashMap<T,java.lang.Integer> getVariablesMapping()

It returns the variables for which assignment in the solution is given.

Specified by:

getVariablesMapping in interface SelectChoicePoint<T extends Var>

Returns:

mapping of variables to the positions in the variables array.

getIndex

public int getIndex()

It returns the current index. Supplying this value in the next invocation of select will make search for next variable faster without comprimising efficiency.

Specified by:

getIndex in interface SelectChoicePoint<T extends Var>

Returns:

internal position of the last variable chosen to be the base of the choice point.

placeSearchVariable

public T placeSearchVariable(int searchPosition,
                             int variablePosition)

It gets as input the index of the variable which is chosen by search to be instantiated at this stage. The variable is positioned at search position.

Parameters:

searchPosition - position at which search store currently choosen variable.

variablePosition - current position of the variable choosen by search.

Returns:

variable choosen to be a base of the choice point.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object