org.chocosolver.solver.search.strategy.decision

Class Decision<E extends Variable>

java.lang.Object

org.chocosolver.solver.search.strategy.decision.Decision<E>

Type Parameters:

E - type of variable handle by this decision

All Implemented Interfaces:

Serializable, ICause

Direct Known Subclasses:

IbexDecision, IntDecision, RealDecision, RootDecision, SetDecision

public abstract class Decision<E extends Variable>
extends Object
implements ICause, Serializable

An abstract which defines a Decision

Since:

2 juil. 2010

Author:

Charles Prud'homme

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int	branch Indication of the decision state.
protected int	max_branching Number of time a decision can be applied.
protected E	var Variable of this decision

Constructor Summary

Constructors

Constructor and Description
Decision(int arity) Create a arity-decision.

Method Summary

Modifier and Type	Method and Description
abstract void	apply() Apply the current decision
void	buildNext() Build the refutation, hasNext() must be called before
Decision<E>	duplicate()
abstract void	free() Free the decision, ie, it can be reused
int	getArity()
abstract Object	getDecisionValue() Return the value object involves in the decision
E	getDecisionVariable() Return the variable object involves in the decision
int	getPosition() Get the position of this decision in the decision path Note that the position a decision is unique, but some decisions taken together have the same rank.
boolean	hasNext() Return true if the decision can be refuted
boolean	isEquivalentTo(Decision dec)
void	reverse() Reverse the decision operator
void	rewind() Force the decision to be in its creation state.
protected void	set(E var) Reuse the decision
void	setPosition(int p) Set the position of this decision in the decision path.
Decision<E>	setRefutable(boolean isRefutable) Indicate whether or not this decision can be refuted if set to false, if the decision(e.g.
int	triesLeft() Return the number of branches left to try

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.chocosolver.solver.ICause

why

Field Detail

var

protected transient E extends Variable var

Variable of this decision

max_branching

protected int max_branching

Number of time a decision can be applied. For unary decision set to 1 , for binary decision, set to 2, ...

branch

protected int branch

Indication of the decision state. 0: not yet applied 1: applied once 2: refuter once, ...

Constructor Detail

Decision

public Decision(int arity)

Create a arity-decision.

Parameters:

arity - how many time this decision can be applied (and then refuted)

Method Detail

setPosition

public final void setPosition(int p)

Set the position of this decision in the decision path. Note that the position a decision is unique, but some decisions taken together have the same rank.

Parameters:

p - position of this decision in the decision path

getPosition

public final int getPosition()

Get the position of this decision in the decision path Note that the position a decision is unique, but some decisions taken together have the same rank.

Returns:

position of this decision in the decision path

hasNext

public final boolean hasNext()

Return true if the decision can be refuted

Returns:

true if the decision can be refuted, false otherwise

buildNext

public final void buildNext()

Build the refutation, hasNext() must be called before

triesLeft

public final int triesLeft()

Return the number of branches left to try

Returns:

number of tries left

setRefutable

public final Decision<E> setRefutable(boolean isRefutable)

Indicate whether or not this decision can be refuted if set to false, if the decision(e.g. x=3) fails instead of backtracking once and applying its negation (e.g. x!=3) the resolver will backtrack twice and negates the previous decision.

Parameters:

isRefutable - set to false to disable refutation

Returns:

this object

getArity

public final int getArity()

Returns:

number of time a decision can be applied. For unary decision set to 1 , for binary decision, set to 2, ...

apply

public abstract void apply()
                    throws ContradictionException

Apply the current decision

Throws:

ContradictionException - if the application of this decision fails

rewind

public final void rewind()

Force the decision to be in its creation state.

set

protected void set(E var)

Reuse the decision

Parameters:

var - the decision object (commonly a variable)

getDecisionVariable

public final E getDecisionVariable()

Return the variable object involves in the decision

Returns:

a variable V

getDecisionValue

public abstract Object getDecisionValue()

Return the value object involves in the decision

Returns:

a value object

free

public abstract void free()

Free the decision, ie, it can be reused

reverse

public void reverse()

Reverse the decision operator

duplicate

public Decision<E> duplicate()

Returns:

a copy of this decision

isEquivalentTo

public boolean isEquivalentTo(Decision dec)

Parameters:

dec - a decision

Returns:

true if the two decisions are equivalent (same variable, same operator, same value)