/*
* 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.sideEffect;
import org.apache.tinkerpop.gremlin.process.traversal.Operator;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.Traverser;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__;
import org.apache.tinkerpop.gremlin.process.traversal.step.Barrier;
import org.apache.tinkerpop.gremlin.process.traversal.step.ByModulating;
import org.apache.tinkerpop.gremlin.process.traversal.step.SideEffectCapable;
import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.GroupStep;
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 org.apache.tinkerpop.gremlin.util.function.HashMapSupplier;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public final class GroupSideEffectStep<S, K, V> extends SideEffectStep<S> implements SideEffectCapable<Map<K, ?>, Map<K, V>>, TraversalParent, ByModulating {
private char state = 'k';
private Traversal.Admin<S, K> keyTraversal;
private Traversal.Admin<S, V> valueTraversal;
private Barrier barrierStep;
///
private String sideEffectKey;
public GroupSideEffectStep(final Traversal.Admin traversal, final String sideEffectKey) {
super(traversal);
this.sideEffectKey = sideEffectKey;
this.valueTraversal = this.integrateChild(__.fold().asAdmin());
this.barrierStep = TraversalHelper.getFirstStepOfAssignableClass(Barrier.class, this.valueTraversal).orElse(null);
this.getTraversal().getSideEffects().registerIfAbsent(this.sideEffectKey, HashMapSupplier.instance(),
new GroupStep.GroupBiOperator<>(null == this.barrierStep ?
Operator.assign :
this.barrierStep.getMemoryComputeKey().getReducer()));
}
@Override
public void modulateBy(final Traversal.Admin<?, ?> kvTraversal) {
if ('k' == this.state) {
this.keyTraversal = this.integrateChild(kvTraversal);
this.state = 'v';
} else if ('v' == this.state) {
this.valueTraversal = this.integrateChild(GroupStep.convertValueTraversal(kvTraversal));
this.barrierStep = TraversalHelper.getFirstStepOfAssignableClass(Barrier.class, this.valueTraversal).orElse(null);
this.getTraversal().getSideEffects().register(this.sideEffectKey, null,
new GroupStep.GroupBiOperator<>(null == this.barrierStep ?
Operator.assign :
this.barrierStep.getMemoryComputeKey().getReducer()));
this.state = 'x';
} else {
throw new IllegalStateException("The key and value traversals for group()-step have already been set: " + this);
}
}
@Override
protected void sideEffect(final Traverser.Admin<S> traverser) {
final Map<K, V> map = new HashMap<>(1);
this.valueTraversal.reset();
this.valueTraversal.addStart(traverser);
if (null == this.barrierStep) {
if (this.valueTraversal.hasNext())
map.put(TraversalUtil.applyNullable(traverser, this.keyTraversal), (V) this.valueTraversal.next());
} else if (this.barrierStep.hasNextBarrier())
map.put(TraversalUtil.applyNullable(traverser, this.keyTraversal), (V) this.barrierStep.nextBarrier());
if (!map.isEmpty())
this.getTraversal().getSideEffects().add(this.sideEffectKey, map);
}
@Override
public String getSideEffectKey() {
return this.sideEffectKey;
}
@Override
public String toString() {
return StringFactory.stepString(this, this.sideEffectKey, this.keyTraversal, this.valueTraversal);
}
@Override
public List<Traversal.Admin<?, ?>> getLocalChildren() {
final List<Traversal.Admin<?, ?>> children = new ArrayList<>(2);
if (null != this.keyTraversal)
children.add(this.keyTraversal);
children.add(this.valueTraversal);
return children;
}
@Override
public Set<TraverserRequirement> getRequirements() {
return this.getSelfAndChildRequirements(TraverserRequirement.OBJECT, TraverserRequirement.BULK, TraverserRequirement.SIDE_EFFECTS);
}
@Override
public GroupSideEffectStep<S, K, V> clone() {
final GroupSideEffectStep<S, K, V> clone = (GroupSideEffectStep<S, K, V>) super.clone();
if (null != this.keyTraversal)
clone.keyTraversal = this.keyTraversal.clone();
clone.valueTraversal = this.valueTraversal.clone();
clone.barrierStep = TraversalHelper.getFirstStepOfAssignableClass(Barrier.class, clone.valueTraversal).orElse(null);
return clone;
}
@Override
public void setTraversal(final Traversal.Admin<?, ?> parentTraversal) {
super.setTraversal(parentTraversal);
this.integrateChild(this.keyTraversal);
this.integrateChild(this.valueTraversal);
}
@Override
public int hashCode() {
int result = super.hashCode() ^ this.sideEffectKey.hashCode();
if (this.keyTraversal != null) result ^= this.keyTraversal.hashCode();
result ^= this.valueTraversal.hashCode();
return result;
}
@Override
public Map<K, V> generateFinalResult(final Map<K, ?> object) {
return GroupStep.doFinalReduction((Map<K, Object>) object, this.valueTraversal);
}
}