Package org.apache.tinkerpop.gremlin.process.traversal.strategy.optimization

Class GValueReductionStrategy

java.lang.Object

org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy<TraversalStrategy.OptimizationStrategy>

org.apache.tinkerpop.gremlin.process.traversal.strategy.optimization.GValueReductionStrategy

All Implemented Interfaces:

Serializable, Comparable<Class<? extends TraversalStrategy>>, TraversalStrategy<TraversalStrategy.OptimizationStrategy>, TraversalStrategy.OptimizationStrategy

public final class GValueReductionStrategy
extends AbstractTraversalStrategy<TraversalStrategy.OptimizationStrategy>
implements TraversalStrategy.OptimizationStrategy

Converts placeholder steps that hold GValue objects to their concrete implementations. While not an optimization in and of itself, the GValue functionality in general, provides a mechanism for traversal optimization so falls in this category. In addition, converting to concrete steps at this stage also allows provider optimization strategies to execute on concrete steps, rather than step interfaces. Concrete steps are much easier to reason about and keep strategy application simple for the vast majority of providers.

Providers hoping to do more advanced optimizations that require GValue objects to be present for their strategies will need to remove GValueReductionStrategy and offer their own mechanism for converting step placeholders to concrete steps. ProviderGValueReductionStrategy is a base class for helping with this need.

See Also:

• Serialized Form

Nested Class Summary

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

TraversalStrategy.DecorationStrategy, TraversalStrategy.FinalizationStrategy, TraversalStrategy.OptimizationStrategy, TraversalStrategy.ProviderOptimizationStrategy, TraversalStrategy.VerificationStrategy

Method Summary

Modifier and Type	Method	Description
void	apply(Traversal.Admin<?,?> traversal)	The transformation the strategy applies to the traversal.
Set<Class<? extends TraversalStrategy.OptimizationStrategy>>	applyPost()	No TinkerPop optimization strategy should be applied following this one.
static GValueReductionStrategy	instance()

Methods inherited from class org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy

equals, hashCode, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

applyPrior, getConfiguration

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy.OptimizationStrategy

compareTo, getTraversalCategory

Method Details

apply

public void apply(Traversal.Admin<?,?> traversal)

Description copied from interface: TraversalStrategy

The transformation the strategy applies to the traversal.

Specified by:

apply in interface TraversalStrategy<TraversalStrategy.OptimizationStrategy>

instance

public static GValueReductionStrategy instance()

applyPost

public Set<Class<? extends TraversalStrategy.OptimizationStrategy>> applyPost()

No TinkerPop optimization strategy should be applied following this one. The default implementation adds GValueReductionStrategy itself so retaining that implementation would create a circular reference so returning an empty list here removes that dependency.

Specified by:

applyPost in interface TraversalStrategy<TraversalStrategy.OptimizationStrategy>

Specified by:

applyPost in interface TraversalStrategy.OptimizationStrategy

Returns:

the set of strategies that must be executed post this one