org.apache.tinkerpop.gremlin.process.traversal.util

Class EmptyTraversalSideEffects

java.lang.Object

org.apache.tinkerpop.gremlin.process.traversal.util.EmptyTraversalSideEffects

All Implemented Interfaces:

Serializable, Cloneable, TraversalSideEffects

public final class EmptyTraversalSideEffects
extends Object
implements TraversalSideEffects

Author:

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

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.tinkerpop.gremlin.process.traversal.TraversalSideEffects

TraversalSideEffects.Exceptions

Field Summary

Fields inherited from interface org.apache.tinkerpop.gremlin.process.traversal.TraversalSideEffects

SIDE_EFFECTS

Method Summary

Modifier and Type	Method and Description
TraversalSideEffects	clone() Cloning is used to duplicate the sideEffects typically in OLAP environments.
<V> Optional<V>	get(String key) Get the sideEffect associated with the provided key.
<V> Optional<Supplier<V>>	getRegisteredSupplier(String key) Get the registered Supplier associated with the specified key.
<S> Optional<Supplier<S>>	getSackInitialValue() If sacks are enabled, get the initial value of the Traverser sack.
<S> Optional<UnaryOperator<S>>	getSackSplitOperator() If sacks are enabled and a split operator has been specified, then get it.
static EmptyTraversalSideEffects	instance()
Set<String>	keys() The keys of the sideEffect which includes registered Supplier keys.
void	mergeInto(TraversalSideEffects sideEffects) Add the current TraversalSideEffects data and suppliers to the provided TraversalSideEffects.
void	registerSupplier(String key, Supplier supplier) Register a Supplier with the provided key.
void	remove(String key) Remove both the value and registered Supplier associated with provided key.
void	set(String key, Object value) Set the specified key to the specified value.
void	setLocalVertex(Vertex vertex) In a distributed GraphComputer traversal, the sideEffects of the traversal are not a single object within a single JVM.
<S> void	setSack(Supplier<S> initialValue, Optional<UnaryOperator<S>> splitOperator) Set the initial value of each Traverser "sack" along with the operator for splitting sacks.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.TraversalSideEffects

forEach, getOrCreate, registerSupplierIfAbsent

Method Detail

set

public void set(String key,
                Object value)

Description copied from interface: TraversalSideEffects

Set the specified key to the specified value. If a Supplier is provided, it is NOT assumed to be a supplier as set by registerSupplier().

Specified by:

set in interface TraversalSideEffects

Parameters:

key - the key

value - the value

get

public <V> Optional<V> get(String key)
                    throws IllegalArgumentException

Description copied from interface: TraversalSideEffects

Get the sideEffect associated with the provided key. If the sideEffect contains an object for the key, return it in an Optional. Else if the sideEffect has a registered Supplier for that key, generate the object, store the object in the sideEffects, and return it.

Specified by:

get in interface TraversalSideEffects

Type Parameters:

V - the type of the value to retrieve

Parameters:

key - the key to get the value for

Returns:

the value associated with key

Throws:

IllegalArgumentException - if the key does not reference an object or a registered supplier.

remove

public void remove(String key)

Description copied from interface: TraversalSideEffects

Remove both the value and registered Supplier associated with provided key.

Specified by:

remove in interface TraversalSideEffects

Parameters:

key - the key of the value and registered supplier to remove

keys

public Set<String> keys()

Description copied from interface: TraversalSideEffects

The keys of the sideEffect which includes registered Supplier keys. In essence, that which is possible to get().

Specified by:

keys in interface TraversalSideEffects

Returns:

the keys of the sideEffect

registerSupplier

public void registerSupplier(String key,
                             Supplier supplier)

Description copied from interface: TraversalSideEffects

Register a Supplier with the provided key. When sideEffects get() are called, if no object exists and there exists a registered supplier for the key, the object is generated. Registered suppliers are used for the lazy generation of sideEffect data.

Specified by:

registerSupplier in interface TraversalSideEffects

Parameters:

key - the key to register the supplier with

supplier - the supplier that will generate an object when get() is called if it hasn't already been created

getRegisteredSupplier

public <V> Optional<Supplier<V>> getRegisteredSupplier(String key)

Description copied from interface: TraversalSideEffects

Get the registered Supplier associated with the specified key.

Specified by:

getRegisteredSupplier in interface TraversalSideEffects

Type Parameters:

V - The object type of the supplier

Parameters:

key - the key associated with the supplier

Returns:

A non-empty optional if the supplier exists

setSack

public <S> void setSack(Supplier<S> initialValue,
                        Optional<UnaryOperator<S>> splitOperator)

Description copied from interface: TraversalSideEffects

Set the initial value of each Traverser "sack" along with the operator for splitting sacks. If no operator is provided, then a direct memory copy is assumed (this is typically good for primitive types and strings).

Specified by:

setSack in interface TraversalSideEffects

Type Parameters:

S - the sack type

Parameters:

initialValue - the initial value supplier of the traverser sack

splitOperator - the split operator for splitting traverser sacks

getSackInitialValue

public <S> Optional<Supplier<S>> getSackInitialValue()

Description copied from interface: TraversalSideEffects

If sacks are enabled, get the initial value of the Traverser sack.

Specified by:

getSackInitialValue in interface TraversalSideEffects

Type Parameters:

S - the sack type

Returns:

the supplier of the initial value of the traverser sack

getSackSplitOperator

public <S> Optional<UnaryOperator<S>> getSackSplitOperator()

Description copied from interface: TraversalSideEffects

If sacks are enabled and a split operator has been specified, then get it. The split operator is used to split a stack when a bifurcation in a Traverser happens.

Specified by:

getSackSplitOperator in interface TraversalSideEffects

Type Parameters:

S - the sack type

Returns:

the operator for splitting a traverser sack

setLocalVertex

public void setLocalVertex(Vertex vertex)

Description copied from interface: TraversalSideEffects

In a distributed GraphComputer traversal, the sideEffects of the traversal are not a single object within a single JVM. Instead, the sideEffects are distributed across the graph and the pieces are stored on the computing vertices. This method is necessary to call when the Traversal is processing the Traversers at a particular Vertex.

Specified by:

setLocalVertex in interface TraversalSideEffects

Parameters:

vertex - the vertex where the traversal is currently executing.

clone

public TraversalSideEffects clone()

Description copied from interface: TraversalSideEffects

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

Specified by:

clone in interface TraversalSideEffects

Overrides:

clone in class Object

Returns:

The cloned sideEffects

mergeInto

public void mergeInto(TraversalSideEffects sideEffects)

Description copied from interface: TraversalSideEffects

Add the current TraversalSideEffects data and suppliers to the provided TraversalSideEffects.

Specified by:

mergeInto in interface TraversalSideEffects

Parameters:

sideEffects - the sideEffects to add this traversal's sideEffect data to.

instance

public static EmptyTraversalSideEffects instance()