gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/sideEffect/SideEffectCapStep.java

/*
 * 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.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalSideEffects;
import org.apache.tinkerpop.gremlin.process.traversal.step.SideEffectCapable;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.SupplyingBarrierStep;
import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement;
import org.apache.tinkerpop.gremlin.process.traversal.util.EmptyTraversal;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;

import java.util.ArrayList;
import java.util.Collections;
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 SideEffectCapStep<S, E> extends SupplyingBarrierStep<S, E> {

    private List<String> sideEffectKeys;
    public transient Map<String, SideEffectCapable<Object, E>> sideEffectCapableSteps;

    public SideEffectCapStep(final Traversal.Admin traversal, final String sideEffectKey, final String... sideEffectKeys) {
        super(traversal);
        this.sideEffectKeys = new ArrayList<>(1 + sideEffectKeys.length);
        this.sideEffectKeys.add(sideEffectKey);
        Collections.addAll(this.sideEffectKeys, sideEffectKeys);
    }

    @Override
    public String toString() {
        return StringFactory.stepString(this, this.sideEffectKeys);
    }

    @Override
    public int hashCode() {
        int result = super.hashCode();
        for (final String sideEffectKey : this.sideEffectKeys) {
            result ^= sideEffectKey.hashCode();
        }
        return result;
    }

    public List<String> getSideEffectKeys() {
        return this.sideEffectKeys;
    }

    @Override
    public Set<TraverserRequirement> getRequirements() {
        return Collections.singleton(TraverserRequirement.SIDE_EFFECTS);
    }

    @Override
    protected E supply() {
        if (null == this.sideEffectCapableSteps) {
            this.sideEffectCapableSteps = new HashMap<>();
            Traversal.Admin<?, ?> parentTraversal = this.getTraversal();
            while (!(parentTraversal instanceof EmptyTraversal)) {
                for (final SideEffectCapable<Object, E> capableStep : TraversalHelper.getStepsOfAssignableClassRecursively(SideEffectCapable.class, parentTraversal)) {
                    if (this.sideEffectKeys.contains(capableStep.getSideEffectKey()) && !this.sideEffectCapableSteps.containsKey(capableStep.getSideEffectKey()))
                        this.sideEffectCapableSteps.put(capableStep.getSideEffectKey(), capableStep);
                }
                if (this.sideEffectKeys.size() == this.sideEffectCapableSteps.size())
                    break;
                parentTraversal = parentTraversal.getParent().asStep().getTraversal();
            }
        }
        ////////////
        if (this.sideEffectKeys.size() == 1) {
            final String sideEffectKey = this.sideEffectKeys.get(0);
            final E result = this.getTraversal().getSideEffects().<E>get(sideEffectKey);
            final SideEffectCapable<Object, E> sideEffectCapable = this.sideEffectCapableSteps.get(sideEffectKey);
            final E finalResult = null == sideEffectCapable ? result : sideEffectCapable.generateFinalResult(result);
            this.getTraversal().getSideEffects().set(sideEffectKey, finalResult);
            return finalResult;
        } else
            return (E) this.getMapOfSideEffects();
    }

    private Map<String, Object> getMapOfSideEffects() {
        final TraversalSideEffects temp = this.getTraversal().getSideEffects();
        final Map<String, Object> sideEffects = new HashMap<>();
        for (final String sideEffectKey : this.sideEffectKeys) {
            if (temp.exists(sideEffectKey)) {
                final E result = temp.get(sideEffectKey);
                final SideEffectCapable<Object, E> sideEffectCapable = this.sideEffectCapableSteps.get(sideEffectKey);
                final E finalResult = null == sideEffectCapable ? result : sideEffectCapable.generateFinalResult(result);
                temp.set(sideEffectKey, finalResult);
                sideEffects.put(sideEffectKey, finalResult);
            }
        }
        return sideEffects;
    }

    @Override
    public SideEffectCapStep<S, E> clone() {
        final SideEffectCapStep<S, E> clone = (SideEffectCapStep<S, E>) super.clone();
        clone.sideEffectCapableSteps = null;
        return clone;
    }
}