Package org.eclipse.rdf4j.repository.sparql.federation

Class SPARQLCrossProductIteration

java.lang.Object

org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<E,X>

org.eclipse.rdf4j.common.iteration.LookAheadIteration<BindingSet,QueryEvaluationException>

org.eclipse.rdf4j.repository.sparql.federation.SPARQLCrossProductIteration

All Implemented Interfaces:

AutoCloseable, CloseableIteration<BindingSet,QueryEvaluationException>, Iteration<BindingSet,QueryEvaluationException>

public class SPARQLCrossProductIteration
extends LookAheadIteration<BindingSet,QueryEvaluationException>

Iteration which forms the cross product of a list of materialized input bindings with each result obtained from the inner iteration. Example: inputBindings := {b1, b2, ...} resultIteration := {r1, r2, ...} getNextElement() returns (r1,b1), (r1, b2), ..., (r2, b1), (r2, b2), ... i.e. compute the cross product per result binding Note that this class is a fully equivalent copy of CrossProductIteration, and is only included here to avoid a circular dependency between the algebra-evaluation module and the sparql-repository module.

Author:

Andreas Schwarte

Field Summary

Fields

Modifier and Type	Field	Description
protected BindingSet	currentInputBinding
protected List<BindingSet>	inputBindings
protected Iterator<BindingSet>	inputBindingsIterator
protected CloseableIteration<BindingSet,QueryEvaluationException>	resultIteration

Constructor Summary

Constructors

Constructor	Description
SPARQLCrossProductIteration(CloseableIteration<BindingSet,QueryEvaluationException> resultIteration, List<BindingSet> inputBindings)

Method Summary

Modifier and Type	Method	Description
protected BindingSet	getNextElement()	Gets the next element.
protected void	handleClose()	Called by AbstractCloseableIteration.close() when it is called for the first time.

Methods inherited from class org.eclipse.rdf4j.common.iteration.LookAheadIteration

hasNext, next, remove

Methods inherited from class org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration

close, isClosed

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.common.iteration.CloseableIteration

stream

Field Detail

inputBindings

protected final List<BindingSet> inputBindings

resultIteration

protected final CloseableIteration<BindingSet,QueryEvaluationException> resultIteration

inputBindingsIterator

protected Iterator<BindingSet> inputBindingsIterator

currentInputBinding

protected BindingSet currentInputBinding

Constructor Detail

SPARQLCrossProductIteration

public SPARQLCrossProductIteration(CloseableIteration<BindingSet,QueryEvaluationException> resultIteration,
                                   List<BindingSet> inputBindings)

Method Detail

getNextElement

protected BindingSet getNextElement()
                             throws QueryEvaluationException

Description copied from class: LookAheadIteration

Gets the next element. Subclasses should implement this method so that it returns the next element.

Specified by:

getNextElement in class LookAheadIteration<BindingSet,QueryEvaluationException>

Returns:

The next element, or null if no more elements are available.

Throws:

QueryEvaluationException

handleClose

protected void handleClose()
                    throws QueryEvaluationException

Description copied from class: AbstractCloseableIteration

Called by AbstractCloseableIteration.close() when it is called for the first time. This method is only called once on each iteration. By default, this method does nothing.

Overrides:

handleClose in class LookAheadIteration<BindingSet,QueryEvaluationException>

Throws:

QueryEvaluationException