/*
* 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.strategy.decoration;
import org.apache.commons.configuration.Configuration;
import org.apache.commons.configuration.MapConfiguration;
import org.apache.tinkerpop.gremlin.process.traversal.P;
import org.apache.tinkerpop.gremlin.process.traversal.Parameterizing;
import org.apache.tinkerpop.gremlin.process.traversal.Traversal;
import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy;
import org.apache.tinkerpop.gremlin.process.traversal.step.HasContainerHolder;
import org.apache.tinkerpop.gremlin.process.traversal.step.filter.HasStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.AddEdgeStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.AddVertexStartStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.AddVertexStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.GraphStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.IdStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertiesStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.HasContainer;
import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
import org.apache.tinkerpop.gremlin.structure.Element;
import org.apache.tinkerpop.gremlin.structure.PropertyType;
import org.apache.tinkerpop.gremlin.structure.T;
import org.apache.tinkerpop.gremlin.structure.util.StringFactory;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;
import java.util.function.Supplier;
/**
* Provides a degree of control over element identifier assignment as some graphs don't provide that feature. This
* strategy provides for identifier assignment by enabling users to utilize vertex and edge indices under the hood,
* thus simulating that capability.
* <p/>
* By default, when an identifier is not supplied by the user, newly generated identifiers are {@link UUID} objects.
* This behavior can be overridden by setting the {@link Builder#idMaker(Supplier)}.
* <p/>
* Unless otherwise specified the identifier is stored in the {@code __id} property. This can be changed by setting
* the {@link Builder#idPropertyKey(String)}
*
* @author Marko A. Rodriguez (http://markorodriguez.com)
* @author Stephen Mallette (http://stephen.genoprime.com)
*/
public final class ElementIdStrategy extends AbstractTraversalStrategy<TraversalStrategy.DecorationStrategy> implements TraversalStrategy.DecorationStrategy {
private final String idPropertyKey;
private final Supplier<Object> idMaker;
private ElementIdStrategy(final String idPropertyKey, final Supplier<Object> idMaker) {
this.idPropertyKey = idPropertyKey;
this.idMaker = idMaker;
}
public String getIdPropertyKey() {
return idPropertyKey;
}
public Supplier<Object> getIdMaker() {
return idMaker;
}
@Override
public void apply(final Traversal.Admin<?, ?> traversal) {
TraversalHelper.getStepsOfAssignableClass(HasStep.class, traversal).stream()
.filter(hasStep -> ((HasStep<?>) hasStep).getHasContainers().get(0).getKey().equals(T.id.getAccessor()))
.forEach(hasStep -> ((HasStep<?>) hasStep).getHasContainers().get(0).setKey(this.idPropertyKey));
if (traversal.getStartStep() instanceof GraphStep) {
final GraphStep graphStep = (GraphStep) traversal.getStartStep();
// only need to apply the custom id if ids were assigned - otherwise we want the full iterator.
// note that it is then only necessary to replace the step if the id is a non-element. other tests
// in the suite validate that items in getIds() is uniform so it is ok to just test the first item
// in the list.
if (graphStep.getIds().length > 0 && !(graphStep.getIds()[0] instanceof Element)) {
if (graphStep instanceof HasContainerHolder)
((HasContainerHolder) graphStep).addHasContainer(new HasContainer(this.idPropertyKey, P.within(Arrays.asList(graphStep.getIds()))));
else
TraversalHelper.insertAfterStep(new HasStep(traversal, new HasContainer(this.idPropertyKey, P.within(Arrays.asList(graphStep.getIds())))), graphStep, traversal);
graphStep.clearIds();
}
}
TraversalHelper.getStepsOfAssignableClass(IdStep.class, traversal).stream().forEach(step -> {
TraversalHelper.replaceStep(step, new PropertiesStep(traversal, PropertyType.VALUE, idPropertyKey), traversal);
});
// in each case below, determine if the T.id is present and if so, replace T.id with the idPropertyKey or if
// it is not present then shove it in there and generate an id
traversal.getSteps().forEach(step -> {
if (step instanceof AddVertexStep || step instanceof AddVertexStartStep || step instanceof AddEdgeStep) {
final Parameterizing parameterizing = (Parameterizing) step;
if (parameterizing.getParameters().contains(T.id))
parameterizing.getParameters().rename(T.id, this.idPropertyKey);
else if (!parameterizing.getParameters().contains(this.idPropertyKey))
parameterizing.getParameters().set(null, this.idPropertyKey, idMaker.get());
}
});
}
public static Builder build() {
return new Builder();
}
@Override
public String toString() {
return StringFactory.traversalStrategyString(this);
}
public final static class Builder {
private String idPropertyKey = "__id";
private Supplier<Object> idMaker = () -> UUID.randomUUID().toString();
private Builder() {
}
/**
* Creates a new unique identifier for the next created {@link Element}.
*/
public Builder idMaker(final Supplier<Object> idMaker) {
this.idMaker = idMaker;
return this;
}
/**
* This key within which to hold the user-specified identifier. This field should be indexed by the
* underlying graph.
*/
public Builder idPropertyKey(final String idPropertyKey) {
this.idPropertyKey = idPropertyKey;
return this;
}
public ElementIdStrategy create() {
return new ElementIdStrategy(idPropertyKey, idMaker);
}
}
public static final String ID_PROPERTY_KEY = "idPropertyKey";
public static final String ID_MAKER = "idMaker";
public static ElementIdStrategy create(final Configuration configuration) {
final ElementIdStrategy.Builder builder = ElementIdStrategy.build();
if (configuration.containsKey(ID_MAKER))
builder.idMaker((Supplier) configuration.getProperty(ID_MAKER));
if (configuration.containsKey(ID_PROPERTY_KEY))
builder.idPropertyKey(configuration.getString(ID_PROPERTY_KEY));
return builder.create();
}
@Override
public Configuration getConfiguration() {
final Map<String, Object> map = new HashMap<>();
map.put(STRATEGY, ElementIdStrategy.class.getCanonicalName());
map.put(ID_PROPERTY_KEY, this.idPropertyKey);
map.put(ID_MAKER, this.idMaker);
return new MapConfiguration(map);
}
}