Class BindLeftJoinIteration

java.lang.Object

org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<BindingSet>

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

org.eclipse.rdf4j.federated.evaluation.iterator.BindLeftJoinIteration

All Implemented Interfaces:

AutoCloseable, Iterator<BindingSet>, CloseableIteration<BindingSet>

public class BindLeftJoinIteration
extends LookAheadIteration<BindingSet>

A LookAheadIteration for processing bind left join results (i.e., result of joining OPTIONAL clauses) Algorithm:

• execute left bind join using regular bound join query
• process result iteration similar to BoundJoinVALUESConversionIteration
• remember seen set of bindings (using index) and add original bindings to those, i.e. put to result return all non-seen bindings directly from the input

Author:

Andreas Schwarte

Field Summary

Fields

Modifier and Type	Field	Description
protected final List<BindingSet>	bindings
protected final ListIterator<BindingSet>	bindingsIterator
protected final CloseableIteration<BindingSet>	iter
protected org.eclipse.collections.impl.set.mutable.primitive.IntHashSet	seenBindingIndexes

Fields inherited from interface CloseableIteration

EMPTY_STATEMENT_ITERATION

Constructor Summary

Constructors

Constructor	Description
BindLeftJoinIteration(CloseableIteration<BindingSet> iter, List<BindingSet> bindings)

Method Summary

Modifier and Type	Method	Description
protected BindingSet	convert(BindingSet bIn, int bIndex)
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 LookAheadIteration

hasNext, next, remove

Methods inherited from class AbstractCloseableIteration

close, isClosed

Methods inherited from class Object

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

Methods inherited from interface CloseableIteration

stream

Methods inherited from interface Iterator

forEachRemaining

Field Details

iter

protected final CloseableIteration<BindingSet> iter

bindings

protected final List<BindingSet> bindings

seenBindingIndexes

protected org.eclipse.collections.impl.set.mutable.primitive.IntHashSet seenBindingIndexes

bindingsIterator

protected final ListIterator<BindingSet> bindingsIterator

Constructor Details

BindLeftJoinIteration

public BindLeftJoinIteration(CloseableIteration<BindingSet> iter,
 List<BindingSet> bindings)

Method Details

getNextElement

protected BindingSet getNextElement()

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>

Returns:

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

handleClose

protected void handleClose()

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.

Specified by:

handleClose in class AbstractCloseableIteration<BindingSet>

convert

protected BindingSet convert(BindingSet bIn,
 int bIndex)
                      throws QueryEvaluationException

Throws:

QueryEvaluationException