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DepthTwo.java
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DepthTwo.java
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/*
* Licensed to Neo Technology under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Neo Technology 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.neo4j.examples.server.plugins;
import java.util.ArrayList;
import java.util.List;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Path;
import org.neo4j.graphdb.Relationship;
import org.neo4j.graphdb.Transaction;
import org.neo4j.graphdb.traversal.Evaluators;
import org.neo4j.graphdb.traversal.TraversalDescription;
import org.neo4j.graphdb.traversal.Uniqueness;
import org.neo4j.server.plugins.Description;
import org.neo4j.server.plugins.PluginTarget;
import org.neo4j.server.plugins.ServerPlugin;
import org.neo4j.server.plugins.Source;
/**
* An extension performing a predefined graph traversal
*/
@Description( "Performs a depth two traversal along all relationship types." )
public class DepthTwo extends ServerPlugin
{
@Description( "Traverse depth two and return the end nodes" )
@PluginTarget( Node.class )
public Iterable<Node> nodesOnDepthTwo( @Source Node node )
{
ArrayList<Node> nodes = new ArrayList<>();
try (Transaction tx = node.getGraphDatabase().beginTx())
{
for ( Node foundNode : getTraversal( node ).traverse( node ).nodes() )
{
nodes.add( foundNode );
}
tx.success();
}
return nodes;
}
@Description( "Traverse depth two and return the last relationships" )
@PluginTarget( Node.class )
public Iterable<Relationship> relationshipsOnDepthTwo( @Source Node node )
{
List<Relationship> rels = new ArrayList<>();
try (Transaction tx = node.getGraphDatabase().beginTx())
{
for ( Relationship rel : getTraversal( node ).traverse( node ).relationships() )
{
rels.add( rel );
}
tx.success();
}
return rels;
}
@Description( "Traverse depth two and return the paths" )
@PluginTarget( Node.class )
public Iterable<Path> pathsOnDepthTwo( @Source Node node )
{
List<Path> paths = new ArrayList<>();
try (Transaction tx = node.getGraphDatabase().beginTx())
{
for ( Path path : getTraversal( node ).traverse( node ) )
{
paths.add( path );
}
tx.success();
}
return paths;
}
private TraversalDescription getTraversal( Node node )
{
return node.getGraphDatabase()
.traversalDescription()
.uniqueness( Uniqueness.RELATIONSHIP_PATH )
.evaluator( Evaluators.atDepth( 2 ) );
}
}