Package org.eclipse.rdf4j.query.algebra.evaluation.iterator

Class LeftJoinIterator

java.lang.Object

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

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

org.eclipse.rdf4j.query.algebra.evaluation.iterator.LeftJoinIterator

All Implemented Interfaces:

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

Direct Known Subclasses:

BadlyDesignedLeftJoinIterator

public class LeftJoinIterator
extends LookAheadIteration<BindingSet,QueryEvaluationException>

Field Summary

Fields

Modifier and Type	Field	Description
private final QueryValueEvaluationStep	joinCondition
private final CloseableIteration<BindingSet,QueryEvaluationException>	leftIter
private final QueryEvaluationStep	prepareRightArg
private CloseableIteration<BindingSet,QueryEvaluationException>	rightIter
private final Set<String>	scopeBindingNames	The set of binding names that are "in scope" for the filter.

Constructor Summary

Constructors

Constructor	Description
LeftJoinIterator(EvaluationStrategy strategy, LeftJoin join, BindingSet bindings, QueryEvaluationContext context)
LeftJoinIterator(QueryEvaluationStep left, QueryEvaluationStep right, QueryValueEvaluationStep joinCondition, BindingSet bindings, Set<String> scopeBindingNamse)

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.
private boolean	isTrue(QueryValueEvaluationStep expr, QueryBindingSet bindings)

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 Details

scopeBindingNames

private final Set<String> scopeBindingNames

The set of binding names that are "in scope" for the filter. The filter must not include bindings that are (only) included because of the depth-first evaluation strategy in the evaluation of the constraint.

leftIter

private final CloseableIteration<BindingSet,QueryEvaluationException> leftIter

rightIter

private CloseableIteration<BindingSet,QueryEvaluationException> rightIter

prepareRightArg

private final QueryEvaluationStep prepareRightArg

joinCondition

private final QueryValueEvaluationStep joinCondition

Constructor Details

LeftJoinIterator

public LeftJoinIterator(EvaluationStrategy strategy,
 LeftJoin join,
 BindingSet bindings,
 QueryEvaluationContext context)
                 throws QueryEvaluationException

Throws:

QueryEvaluationException

LeftJoinIterator

public LeftJoinIterator(QueryEvaluationStep left,
 QueryEvaluationStep right,
 QueryValueEvaluationStep joinCondition,
 BindingSet bindings,
 Set<String> scopeBindingNamse)
                 throws QueryEvaluationException

Throws:

QueryEvaluationException

Method Details

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

isTrue

private boolean isTrue(QueryValueEvaluationStep expr,
 QueryBindingSet bindings)

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