/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.tinkerpop.gremlin.process.traversal.step.filter;
import org.apache.tinkerpop.gremlin.process.traversal.Pop;
import org.apache.tinkerpop.gremlin.process.traversal.Step;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.Traverser;
import org.apache.tinkerpop.gremlin.process.traversal.step.PathProcessor;
import org.apache.tinkerpop.gremlin.process.traversal.step.Scoping;
import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.MapStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.StartStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.ProfileStep;
import org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.ConnectiveStrategy;
import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalUtil;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public final class WhereTraversalStep<S> extends FilterStep<S> implements TraversalParent, Scoping, PathProcessor {
protected Traversal.Admin<?, ?> whereTraversal;
protected final Set<String> scopeKeys = new HashSet<>();
protected Set<String> keepLabels;
public WhereTraversalStep(final Traversal.Admin traversal, final Traversal<?, ?> whereTraversal) {
super(traversal);
this.whereTraversal = whereTraversal.asAdmin();
this.configureStartAndEndSteps(this.whereTraversal);
if (this.scopeKeys.isEmpty())
throw new IllegalArgumentException("A where()-traversal must have at least a start or end label (i.e. variable): " + whereTraversal);
this.whereTraversal = this.integrateChild(this.whereTraversal);
}
private void configureStartAndEndSteps(final Traversal.Admin<?, ?> whereTraversal) {
ConnectiveStrategy.instance().apply(whereTraversal);
//// START STEP to WhereStartStep
final Step<?, ?> startStep = whereTraversal.getStartStep();
if (startStep instanceof ConnectiveStep || startStep instanceof NotStep) { // for conjunction- and not-steps
((TraversalParent) startStep).getLocalChildren().forEach(this::configureStartAndEndSteps);
} else if (StartStep.isVariableStartStep(startStep)) { // as("a").out()... traversals
final String label = startStep.getLabels().iterator().next();
this.scopeKeys.add(label);
TraversalHelper.replaceStep(startStep, new WhereStartStep(whereTraversal, label), whereTraversal);
} else if (!whereTraversal.getEndStep().getLabels().isEmpty()) { // ...out().as("a") traversals
TraversalHelper.insertBeforeStep(new WhereStartStep(whereTraversal, null), (Step) startStep, whereTraversal);
}
//// END STEP to WhereEndStep
final Step<?, ?> endStep = whereTraversal.getEndStep();
if (!endStep.getLabels().isEmpty()) {
if (endStep.getLabels().size() > 1)
throw new IllegalArgumentException("The end step of a where()-traversal can only have one label: " + endStep);
final String label = endStep.getLabels().iterator().next();
this.scopeKeys.add(label);
endStep.removeLabel(label);
whereTraversal.addStep(new WhereEndStep(whereTraversal, label));
}
}
@Override
public ElementRequirement getMaxRequirement() {
return TraversalHelper.getVariableLocations(this.whereTraversal).contains(Scoping.Variable.START) ?
PathProcessor.super.getMaxRequirement() :
ElementRequirement.ID;
}
@Override
protected Traverser.Admin<S> processNextStart() {
return PathProcessor.processTraverserPathLabels(super.processNextStart(), this.keepLabels);
}
@Override
protected boolean filter(final Traverser.Admin<S> traverser) {
return TraversalUtil.test((Traverser.Admin) traverser, this.whereTraversal);
}
@Override
public List<Traversal.Admin<?, ?>> getLocalChildren() {
return null == this.whereTraversal ? Collections.emptyList() : Collections.singletonList(this.whereTraversal);
}
@Override
public String toString() {
return StringFactory.stepString(this, this.whereTraversal);
}
@Override
public Set<String> getScopeKeys() {
return Collections.unmodifiableSet(this.scopeKeys);
}
@Override
public WhereTraversalStep<S> clone() {
final WhereTraversalStep<S> clone = (WhereTraversalStep<S>) super.clone();
clone.whereTraversal = this.whereTraversal.clone();
return clone;
}
@Override
public void setTraversal(final Traversal.Admin<?, ?> parentTraversal) {
super.setTraversal(parentTraversal);
integrateChild(this.whereTraversal);
}
@Override
public int hashCode() {
return super.hashCode() ^ this.whereTraversal.hashCode();
}
@Override
public Set<TraverserRequirement> getRequirements() {
return this.getSelfAndChildRequirements(TraverserRequirement.OBJECT, TraverserRequirement.SIDE_EFFECTS);
}
@Override
public void setKeepLabels(final Set<String> keepLabels) {
this.keepLabels = keepLabels;
}
@Override
public Set<String> getKeepLabels() {
return this.keepLabels;
}
//////////////////////////////
public static class WhereStartStep<S> extends MapStep<S, Object> implements Scoping {
private String selectKey;
public WhereStartStep(final Traversal.Admin traversal, final String selectKey) {
super(traversal);
this.selectKey = selectKey;
}
@Override
protected Object map(final Traverser.Admin<S> traverser) {
if (this.getTraversal().getEndStep() instanceof WhereEndStep)
((WhereEndStep) this.getTraversal().getEndStep()).processStartTraverser(traverser);
else if (this.getTraversal().getEndStep() instanceof ProfileStep && this.getTraversal().getEndStep().getPreviousStep() instanceof WhereEndStep) // TOTAL SUCKY HACK!
((WhereEndStep) this.getTraversal().getEndStep().getPreviousStep()).processStartTraverser(traverser);
return null == this.selectKey ? traverser.get() : this.getScopeValue(Pop.last, this.selectKey, traverser);
}
@Override
public String toString() {
return StringFactory.stepString(this, this.selectKey);
}
@Override
public int hashCode() {
return super.hashCode() ^ (null == this.selectKey ? "null".hashCode() : this.selectKey.hashCode());
}
public void removeScopeKey() {
this.selectKey = null;
}
@Override
public Set<String> getScopeKeys() {
return null == this.selectKey ? Collections.emptySet() : Collections.singleton(this.selectKey);
}
}
public static class WhereEndStep extends FilterStep<Object> implements Scoping {
private final String matchKey;
private Object matchValue = null;
public WhereEndStep(final Traversal.Admin traversal, final String matchKey) {
super(traversal);
this.matchKey = matchKey;
}
public void processStartTraverser(final Traverser.Admin traverser) {
if (null != this.matchKey)
this.matchValue = this.getScopeValue(Pop.last, this.matchKey, traverser);
}
@Override
protected boolean filter(final Traverser.Admin<Object> traverser) {
return null == this.matchKey || traverser.get().equals(this.matchValue);
}
@Override
public String toString() {
return StringFactory.stepString(this, this.matchKey);
}
@Override
public int hashCode() {
return super.hashCode() ^ (null == this.matchKey ? "null".hashCode() : this.matchKey.hashCode());
}
@Override
public Set<String> getScopeKeys() {
return null == this.matchKey ? Collections.emptySet() : Collections.singleton(this.matchKey);
}
}
//////////////////////////////
}