org.chocosolver.solver.search.strategy.decision

Class DecisionPath

java.lang.Object

org.chocosolver.solver.search.strategy.decision.DecisionMaker

org.chocosolver.solver.search.strategy.decision.DecisionPath

All Implemented Interfaces:

Serializable

public class DecisionPath
extends DecisionMaker
implements Serializable

To handle set of decisions.

Decisions are added to this set of decisions with a call to pushDecision(Decision), Decisions are then applied in a call to apply(), and removed in a call to synchronize().
Note that, if more than one decision is added before calling apply(), these decisions belong to the same level. They will be applied at the same time in a call to apply(), and remove at the same time in a call to synchronize(). Otherwise, only one decision is applied/removed at a time.
First decision is always RootDecision.ROOT, so, size() returns at least 1.

Project: choco-solver.

Since:

11/03/2016.

Author:

Charles Prud'homme

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected int[]	levels Indices of level in decisions
protected IStateInt	mLevel Store the sizes of decisions during search, to evaluate which decisions are part of the same level.

Constructor Summary

Constructors

Constructor and Description
DecisionPath(IEnvironment environment) Create a decision path

Method Summary

Modifier and Type	Method and Description
void	apply() Apply decisions pushed since the last call to this method.
Decision	getDecision(int i) Return the decision in position i in this decision path, or null if no decision exists at that position.
Decision	getLastDecision() Retrieves, but not removes, the last decision of the decision path.
int	indexPreviousLevelLastLevel() Return the position of the first decision of the last level.
String	lastDecisionToString()
void	pushDecision(Decision decision) Add a decision at the decision path.
int	size() Return the number of decision in this decision path.
void	synchronize() Synchronizes the decision path after a backtrack.
String	toString()
void	transferInto(Collection<Decision> aList, boolean includeRootDecision) Add all decisions of this decision path into a list of decision

Methods inherited from class org.chocosolver.solver.search.strategy.decision.DecisionMaker

makeIntDecision, makeRealDecision, makeSetDecision

Methods inherited from class java.lang.Object

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

Field Detail

mLevel

protected IStateInt mLevel

Store the sizes of decisions during search, to evaluate which decisions are part of the same level.

levels

protected int[] levels

Indices of level in decisions

Constructor Detail

DecisionPath

public DecisionPath(IEnvironment environment)

Create a decision path

Parameters:

environment - backtracking environment

Method Detail

apply

public void apply()
           throws ContradictionException

Apply decisions pushed since the last call to this method. If more than one decision are applied in this call, they are automatically force to not be refuted, and are considered to belong to the same level.

Throws:

ContradictionException - if one decision application fails

pushDecision

public void pushDecision(Decision decision)

Add a decision at the decision path.

Parameters:

decision - the decision to add

synchronize

public void synchronize()

Synchronizes the decision path after a backtrack. Removes all decisions with level greater or equal to the current level. Recall that the very first decision, RootDecision.ROOT, can not be removed from this.

getLastDecision

public Decision getLastDecision()

Retrieves, but not removes, the last decision of the decision path. Recall that the very first decision of this decision path is RootDecision.ROOT.

Returns:

the last decision of the decision path.

indexPreviousLevelLastLevel

public int indexPreviousLevelLastLevel()

Return the position of the first decision of the last level. Except for LNS first meta-decision, this should return the position of the last decision

Returns:

the position of the first decision of the last level.

size

public int size()

Return the number of decision in this decision path. Recall that this decisions path contains at least one decision: RootDecision.ROOT.

Returns:

the size of the decision path

getDecision

public Decision getDecision(int i)

Return the decision in position i in this decision path, or null if no decision exists at that position.

Parameters:

i - index of the decision to return

Returns:

the decision in position i in this decision path

Throws:

IndexOutOfBoundsException - if the index is out of range (index < 0 || index >= size())

transferInto

public void transferInto(Collection<Decision> aList,
                         boolean includeRootDecision)

Add all decisions of this decision path into a list of decision

Parameters:

aList - list to populate

includeRootDecision - set to true to include the very first fake decision, ROOT, in the list.

lastDecisionToString

public String lastDecisionToString()

Returns:

a pretty print of the downmost decision(s)

toString

public String toString()

Overrides:

toString in class Object