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GH-5286 Generalize concepts for evaluation steps and condition
1 parent a8ae08b commit db12fd1

13 files changed

+409
-355
lines changed

‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/QueryValueEvaluationStep.java

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@@ -12,12 +12,14 @@
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package org.eclipse.rdf4j.query.algebra.evaluation;
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import java.util.function.Function;
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import java.util.function.Predicate;
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import org.eclipse.rdf4j.model.Value;
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import org.eclipse.rdf4j.query.BindingSet;
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import org.eclipse.rdf4j.query.QueryEvaluationException;
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import org.eclipse.rdf4j.query.algebra.ValueConstant;
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import org.eclipse.rdf4j.query.algebra.ValueExpr;
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import org.eclipse.rdf4j.query.algebra.evaluation.util.QueryEvaluationUtility;
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/**
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* A step in the query evaluation that works on ValueExpresions.
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Value evaluate(BindingSet bindings)
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throws QueryEvaluationException;
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default Predicate<BindingSet> asPredicate() {
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return bs -> {
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try {
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Value value = evaluate(bs);
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return QueryEvaluationUtility.getEffectiveBooleanValue(value).orElse(false);
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} catch (ValueExprEvaluationException e) {
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// Ignore, condition not evaluated successfully
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return false;
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}
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};
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}
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/**
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* If an value expression results in a constant then it may be executed once per query invocation. This can reduce
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* computation time significantly.

‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/impl/evaluationsteps/LeftJoinQueryEvaluationStep.java

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@@ -20,6 +20,7 @@
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryEvaluationStep;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryValueEvaluationStep;
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import org.eclipse.rdf4j.query.algebra.evaluation.impl.QueryEvaluationContext;
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import org.eclipse.rdf4j.query.algebra.evaluation.impl.evaluationsteps.values.ScopedQueryValueEvaluationStep;
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import org.eclipse.rdf4j.query.algebra.evaluation.iterator.*;
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import org.eclipse.rdf4j.query.algebra.helpers.TupleExprs;
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import org.eclipse.rdf4j.query.algebra.helpers.collectors.VarNameCollector;
@@ -125,13 +126,13 @@ public static QueryEvaluationStep determineRightEvaluationStep(
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if (joinCondition == null) {
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return prepareRightArg;
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} else if (canEvaluateConditionBasedOnLeftHandSide(join)) {
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return new LeftJoinPreFilterQueryEvaluationStep(
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return new PreFilterQueryEvaluationStep(
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prepareRightArg,
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new ScopeBindingsJoinConditionEvaluator(join.getAssuredBindingNames(), joinCondition));
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new ScopedQueryValueEvaluationStep(join.getAssuredBindingNames(), joinCondition));
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} else {
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return new LeftJoinPostFilterQueryEvaluationStep(
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return new PostFilterQueryEvaluationStep(
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prepareRightArg,
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new ScopeBindingsJoinConditionEvaluator(scopeBindingNames, joinCondition));
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new ScopedQueryValueEvaluationStep(scopeBindingNames, joinCondition));
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}
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}
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‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/impl/evaluationsteps/PostFilterQueryEvaluationStep.java

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/*******************************************************************************
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* Copyright (c) 2025 Eclipse RDF4J contributors.
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*
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Distribution License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/org/documents/edl-v10.php.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*******************************************************************************/
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package org.eclipse.rdf4j.query.algebra.evaluation.impl.evaluationsteps;
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import java.util.function.Predicate;
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import org.eclipse.rdf4j.common.iteration.CloseableIteration;
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import org.eclipse.rdf4j.common.iteration.FilterIteration;
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import org.eclipse.rdf4j.query.BindingSet;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryEvaluationStep;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryValueEvaluationStep;
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public class PostFilterQueryEvaluationStep implements QueryEvaluationStep {
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private final QueryEvaluationStep wrapped;
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private final Predicate<BindingSet> condition;
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public PostFilterQueryEvaluationStep(QueryEvaluationStep wrapped,
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QueryValueEvaluationStep condition) {
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this.wrapped = wrapped;
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this.condition = condition.asPredicate();
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}
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@Override
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public CloseableIteration<BindingSet> evaluate(BindingSet leftBindings) {
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var rightIteration = wrapped.evaluate(leftBindings);
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if (rightIteration == QueryEvaluationStep.EMPTY_ITERATION) {
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return rightIteration;
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}
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return new FilterIteration<>(rightIteration) {
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@Override
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protected boolean accept(BindingSet bindings) {
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return condition.test(bindings);
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}
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@Override
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protected void handleClose() {
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// Nothing to close
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}
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};
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}
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}

‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/impl/evaluationsteps/PreFilterQueryEvaluationStep.java

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/*******************************************************************************
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* Copyright (c) 2025 Eclipse RDF4J contributors.
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*
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Distribution License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/org/documents/edl-v10.php.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*******************************************************************************/
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package org.eclipse.rdf4j.query.algebra.evaluation.impl.evaluationsteps;
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import java.util.function.Predicate;
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import org.eclipse.rdf4j.common.iteration.CloseableIteration;
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import org.eclipse.rdf4j.query.BindingSet;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryEvaluationStep;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryValueEvaluationStep;
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public class PreFilterQueryEvaluationStep implements QueryEvaluationStep {
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private final QueryEvaluationStep wrapped;
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private final Predicate<BindingSet> condition;
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public PreFilterQueryEvaluationStep(QueryEvaluationStep wrapped,
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QueryValueEvaluationStep condition) {
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this.wrapped = wrapped;
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this.condition = condition.asPredicate();
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}
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@Override
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public CloseableIteration<BindingSet> evaluate(BindingSet leftBindings) {
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if (!condition.test(leftBindings)) {
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// Usage of this method assume this instance is returned
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return QueryEvaluationStep.EMPTY_ITERATION;
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}
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return wrapped.evaluate(leftBindings);
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}
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}

‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/impl/evaluationsteps/values/ScopedQueryValueEvaluationStep.java

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/*******************************************************************************
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* Copyright (c) 2025 Eclipse RDF4J contributors.
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*
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Distribution License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/org/documents/edl-v10.php.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*******************************************************************************/
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package org.eclipse.rdf4j.query.algebra.evaluation.impl.evaluationsteps.values;
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import java.util.Set;
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import org.eclipse.rdf4j.model.Value;
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import org.eclipse.rdf4j.query.Binding;
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import org.eclipse.rdf4j.query.BindingSet;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryBindingSet;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryValueEvaluationStep;
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public class ScopedQueryValueEvaluationStep implements QueryValueEvaluationStep {
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/**
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* The set of binding names that are "in scope" for the filter. The filter must not include bindings that are (only)
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* included because of the depth-first evaluation strategy in the evaluation of the constraint.
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*/
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private final Set<String> scopeBindingNames;
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private final QueryValueEvaluationStep wrapped;
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public ScopedQueryValueEvaluationStep(Set<String> scopeBindingNames, QueryValueEvaluationStep condition) {
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this.scopeBindingNames = scopeBindingNames;
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this.wrapped = condition;
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}
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@Override
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public Value evaluate(BindingSet bindings) {
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BindingSet scopeBindings = createScopeBindings(scopeBindingNames, bindings);
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return wrapped.evaluate(scopeBindings);
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}
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private BindingSet createScopeBindings(Set<String> scopeBindingNames, BindingSet bindings) {
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QueryBindingSet scopeBindings = new QueryBindingSet(scopeBindingNames.size());
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for (String scopeBindingName : scopeBindingNames) {
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Binding binding = bindings.getBinding(scopeBindingName);
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if (binding != null) {
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scopeBindings.addBinding(binding);
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}
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}
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return scopeBindings;
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}
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}

‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/LeftJoinIterator.java

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*******************************************************************************/
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package org.eclipse.rdf4j.query.algebra.evaluation.iterator;
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import java.util.NoSuchElementException;
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import org.eclipse.rdf4j.common.iteration.CloseableIteration;
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import org.eclipse.rdf4j.common.iteration.LookAheadIteration;
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import org.eclipse.rdf4j.query.BindingSet;
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import org.eclipse.rdf4j.query.algebra.evaluation.EvaluationStrategy;
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import org.eclipse.rdf4j.query.algebra.evaluation.QueryEvaluationStep;
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import java.util.NoSuchElementException;
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public class LeftJoinIterator extends LookAheadIteration<BindingSet> {
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/*-----------*
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* Variables *

‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/LeftJoinPostFilterQueryEvaluationStep.java

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‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/LeftJoinPreFilterQueryEvaluationStep.java

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‎core/queryalgebra/evaluation/src/main/java/org/eclipse/rdf4j/query/algebra/evaluation/iterator/ScopeBindingsJoinConditionEvaluator.java

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