com.tinkerpop.gremlin.process.util

Class EmptyTraversal<S,E>

java.lang.Object

com.tinkerpop.gremlin.process.util.EmptyTraversal<S,E>

All Implemented Interfaces:

Traversal<S,E>, Traversal.Admin<S,E>, java.lang.Cloneable, java.util.Iterator<E>

Direct Known Subclasses:

EmptyGraphTraversal

public class EmptyTraversal<S,E>
extends java.lang.Object
implements Traversal.Admin<S,E>

Author:

Marko A. Rodriguez (http://markorodriguez.com)

Nested Class Summary

Nested classes/interfaces inherited from interface com.tinkerpop.gremlin.process.Traversal

Traversal.Admin<S,E>, Traversal.Exceptions

Field Summary

Fields inherited from interface com.tinkerpop.gremlin.process.Traversal

OF

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	EmptyTraversal()

Method Summary

Modifier and Type	Method and Description
void	addStart(Traverser<S> start) Add a single Traverser object to the head of the traversal.
void	addStarts(java.util.Iterator<Traverser<S>> starts) Add an iterator of Traverser objects to the head/start of the traversal.
<S2,E2> Traversal<S2,E2>	addStep(int index, Step<?,?> step)
<E2> Traversal<S,E2>	addStep(Step<?,E2> step) Add a Step to the end of the traversal.
void	applyStrategies(TraversalEngine engine) Apply the registered TraversalStrategies to the traversal.
Traversal.Admin<S,E>	asAdmin() Get access to administrative methods of the traversal via its accompanying Traversal.Admin.
EmptyTraversal<S,E>	clone() Cloning is used to duplicate the traversal typically in OLAP environments.
boolean	equals(java.lang.Object object)
TraversalSideEffects	getSideEffects() Get the TraversalSideEffects associated with the traversal.
java.util.List<Step>	getSteps() Get the Step instances associated with this traversal.
TraversalStrategies	getStrategies() Get the TraversalStrategies associated with this traversal.
java.util.Optional<TraversalEngine>	getTraversalEngine() When the TraversalStrategies have been applied, the destined TraversalEngine has been declared.
TraversalHolder<?,?>	getTraversalHolder()
TraverserGenerator	getTraverserGenerator() Get the TraverserGenerator associated with this traversal.
int	hashCode()
boolean	hasNext()
static <A,B> EmptyTraversal<A,B>	instance()
E	next()
<S2,E2> Traversal<S2,E2>	removeStep(int index)
void	setSideEffects(TraversalSideEffects sideEffects) Set the TraversalSideEffects of this traversal.
void	setStrategies(TraversalStrategies traversalStrategies) Set the TraversalStrategies to be used by this traversal at evaluation time.
void	setTraversalHolder(TraversalHolder<?,?> step)
Traversal<S,E>	submit(GraphComputer computer) Submit the traversal to a GraphComputer for OLAP execution.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.tinkerpop.gremlin.process.Traversal.Admin

removeStep, reset, reverse

Methods inherited from interface com.tinkerpop.gremlin.process.Traversal

fill, forEachRemaining, iterate, next, toBulkSet, toList, toSet, tryNext

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Constructor Detail

EmptyTraversal

protected EmptyTraversal()

Method Detail

instance

public static <A,B> EmptyTraversal<A,B> instance()

asAdmin

public Traversal.Admin<S,E> asAdmin()

Description copied from interface: Traversal

Get access to administrative methods of the traversal via its accompanying Traversal.Admin.

Specified by:

asAdmin in interface Traversal<S,E>

Returns:

the admin of this traversal

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<E>

next

public E next()

Specified by:

next in interface java.util.Iterator<E>

getSideEffects

public TraversalSideEffects getSideEffects()

Description copied from interface: Traversal.Admin

Get the TraversalSideEffects associated with the traversal.

Specified by:

getSideEffects in interface Traversal.Admin<S,E>

Returns:

The traversal sideEffects

applyStrategies

public void applyStrategies(TraversalEngine engine)

Description copied from interface: Traversal.Admin

Apply the registered TraversalStrategies to the traversal. Once the strategies are applied, the traversal is "locked" and can no longer have steps added to it. The order of operations for strategy applications should be: globally id steps, apply strategies to root traversal, then to nested traversals.

Specified by:

applyStrategies in interface Traversal.Admin<S,E>

Parameters:

engine - the engine that will ultimately execute the traversal.

getTraversalEngine

public java.util.Optional<TraversalEngine> getTraversalEngine()

Description copied from interface: Traversal.Admin

When the TraversalStrategies have been applied, the destined TraversalEngine has been declared. Once a traversal engine has been declared, the traversal can no longer be extended, only executed.

Specified by:

getTraversalEngine in interface Traversal.Admin<S,E>

Returns:

whether the traversal engine has been defined or not.

addStarts

public void addStarts(java.util.Iterator<Traverser<S>> starts)

Description copied from interface: Traversal.Admin

Add an iterator of Traverser objects to the head/start of the traversal. Users should typically not need to call this method. For dynamic inject of data, they should use InjectStep.

Specified by:

addStarts in interface Traversal.Admin<S,E>

Parameters:

starts - an iterators of traversers

addStart

public void addStart(Traverser<S> start)

Description copied from interface: Traversal.Admin

Add a single Traverser object to the head of the traversal. Users should typically not need to call this method. For dynamic inject of data, they should use InjectStep.

Specified by:

addStart in interface Traversal.Admin<S,E>

Parameters:

start - a traverser to add to the traversal

addStep

public <E2> Traversal<S,E2> addStep(Step<?,E2> step)

Description copied from interface: Traversal.Admin

Add a Step to the end of the traversal. This method should automatically re-link the step accordingly (see TraversalHelper.reLinkSteps(com.tinkerpop.gremlin.process.Traversal.Admin<?, ?>)). If the TraversalStrategies have already been applied, then an IllegalStateException is throw stating the traversal is locked.

Specified by:

addStep in interface Traversal.Admin<S,E>

Type Parameters:

E2 - the output of the step

Parameters:

step - the step to add

Returns:

the updated traversal

getSteps

public java.util.List<Step> getSteps()

Description copied from interface: Traversal.Admin

Get the Step instances associated with this traversal. The steps are ordered according to their linked list structure as defined by Step.getPreviousStep() and Step.getNextStep().

Specified by:

getSteps in interface Traversal.Admin<S,E>

Returns:

the ordered steps of the traversal

submit

public Traversal<S,E> submit(GraphComputer computer)

Description copied from interface: Traversal

Submit the traversal to a GraphComputer for OLAP execution. This method should apply the traversal strategies for TraversalEngine.COMPUTER. Then register and execute the traversal via TraversalVertexProgram. Then wrap the ComputerResult in a new Traversal containing a ComputerResultStep.

Specified by:

submit in interface Traversal<S,E>

Parameters:

computer - the GraphComputer to execute the traversal on

Returns:

a new traversal with the starts being the results of the TraversalVertexProgram

clone

public EmptyTraversal<S,E> clone()
                          throws java.lang.CloneNotSupportedException

Description copied from interface: Traversal

Cloning is used to duplicate the traversal typically in OLAP environments.

Specified by:

clone in interface Traversal<S,E>

Overrides:

clone in class java.lang.Object

Returns:

The cloned traversal

Throws:

java.lang.CloneNotSupportedException

getTraverserGenerator

public TraverserGenerator getTraverserGenerator()

Description copied from interface: Traversal.Admin

Get the TraverserGenerator associated with this traversal. The traversal generator creates Traverser instances that are respective of the traversal definition.

Specified by:

getTraverserGenerator in interface Traversal.Admin<S,E>

Returns:

the generator of traversers

setSideEffects

public void setSideEffects(TraversalSideEffects sideEffects)

Description copied from interface: Traversal.Admin

Set the TraversalSideEffects of this traversal.

Specified by:

setSideEffects in interface Traversal.Admin<S,E>

Parameters:

sideEffects - the sideEffects to set for this traversal.

getStrategies

public TraversalStrategies getStrategies()

Description copied from interface: Traversal.Admin

Get the TraversalStrategies associated with this traversal.

Specified by:

getStrategies in interface Traversal.Admin<S,E>

Returns:

the strategies associated with this traversal

setTraversalHolder

public void setTraversalHolder(TraversalHolder<?,?> step)

Specified by:

setTraversalHolder in interface Traversal.Admin<S,E>

getTraversalHolder

public TraversalHolder<?,?> getTraversalHolder()

Specified by:

getTraversalHolder in interface Traversal.Admin<S,E>

setStrategies

public void setStrategies(TraversalStrategies traversalStrategies)

Description copied from interface: Traversal.Admin

Set the TraversalStrategies to be used by this traversal at evaluation time.

Specified by:

setStrategies in interface Traversal.Admin<S,E>

Parameters:

traversalStrategies - the strategies to use on this traversal

addStep

public <S2,E2> Traversal<S2,E2> addStep(int index,
                                        Step<?,?> step)
                                 throws java.lang.IllegalStateException

Specified by:

addStep in interface Traversal.Admin<S,E>

Throws:

java.lang.IllegalStateException

removeStep

public <S2,E2> Traversal<S2,E2> removeStep(int index)
                                    throws java.lang.IllegalStateException

Specified by:

removeStep in interface Traversal.Admin<S,E>

Throws:

java.lang.IllegalStateException

equals

public boolean equals(java.lang.Object object)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object