/**
* Copyright (c) 2002-2011 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.traversal;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.Expander;
import org.neo4j.graphdb.Node;
import org.neo4j.graphdb.Path;
import org.neo4j.graphdb.RelationshipExpander;
import org.neo4j.graphdb.RelationshipType;
import org.neo4j.graphdb.traversal.BranchOrderingPolicy;
import org.neo4j.graphdb.traversal.Evaluation;
import org.neo4j.graphdb.traversal.Evaluator;
import org.neo4j.graphdb.traversal.Evaluators;
import org.neo4j.graphdb.traversal.PruneEvaluator;
import org.neo4j.graphdb.traversal.TraversalDescription;
import org.neo4j.graphdb.traversal.Traverser;
import org.neo4j.graphdb.traversal.UniquenessFactory;
import org.neo4j.helpers.Predicate;
import org.neo4j.kernel.StandardExpander;
import org.neo4j.kernel.Traversal;
import org.neo4j.kernel.Uniqueness;
public final class TraversalDescriptionImpl implements TraversalDescription
{
public TraversalDescriptionImpl()
{
this( StandardExpander.DEFAULT, Uniqueness.NODE_GLOBAL, null,
Evaluators.all(), Traversal.preorderDepthFirst() );
}
final Expander expander;
final UniquenessFactory uniqueness;
final Object uniquenessParameter;
final Evaluator evaluator;
final BranchOrderingPolicy branchSelector;
private TraversalDescriptionImpl( Expander expander,
UniquenessFactory uniqueness, Object uniquenessParameter,
Evaluator evaluator, BranchOrderingPolicy branchSelector )
{
this.expander = expander;
this.uniqueness = uniqueness;
this.uniquenessParameter = uniquenessParameter;
this.evaluator = evaluator;
this.branchSelector = branchSelector;
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#traverse(org.neo4j.graphdb.Node)
*/
public Traverser traverse( Node startNode )
{
return new TraverserImpl( this, startNode );
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#uniqueness(org.neo4j.graphdb.traversal.Uniqueness)
*/
public TraversalDescription uniqueness( UniquenessFactory uniqueness )
{
return new TraversalDescriptionImpl( expander, uniqueness, null,
evaluator, branchSelector );
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#uniqueness(org.neo4j.graphdb.traversal.Uniqueness, java.lang.Object)
*/
public TraversalDescription uniqueness( UniquenessFactory uniqueness,
Object parameter )
{
if ( this.uniqueness == uniqueness )
{
if ( uniquenessParameter == null ? parameter == null
: uniquenessParameter.equals( parameter ) )
{
return this;
}
}
return new TraversalDescriptionImpl( expander, uniqueness, parameter,
evaluator, branchSelector );
}
public TraversalDescription prune( PruneEvaluator pruning )
{
return evaluator( pruning == PruneEvaluator.NONE ? Evaluators.all() :
new WrappedPruneEvaluator( pruning ) );
}
public TraversalDescription filter( Predicate<Path> filter )
{
Evaluator evaluator = null;
if ( filter == Traversal.returnAll() )
{
evaluator = Evaluators.all();
}
else if ( filter == Traversal.returnAllButStartNode() )
{
evaluator = Evaluators.excludeStartPosition();
}
else
{
evaluator = new WrappedFilter( filter );
}
return evaluator( evaluator );
}
public TraversalDescription evaluator( Evaluator evaluator )
{
if ( this.evaluator == evaluator )
{
return this;
}
nullCheck( evaluator, Evaluator.class, "RETURN_ALL" );
return new TraversalDescriptionImpl( expander, uniqueness, uniquenessParameter,
addBlaEvaluator( evaluator ), branchSelector );
}
private Evaluator addBlaEvaluator( Evaluator evaluator )
{
if ( this.evaluator instanceof MultiEvaluator )
{
return ((MultiEvaluator) this.evaluator).add( evaluator );
}
else
{
if ( this.evaluator == Evaluators.all() )
{
return evaluator;
}
else
{
return new MultiEvaluator( new Evaluator[] { this.evaluator, evaluator } );
}
}
}
private static <T> void nullCheck( T parameter, Class<T> parameterType,
String defaultName )
{
if ( parameter == null )
{
String typeName = parameterType.getSimpleName();
throw new IllegalArgumentException( typeName
+ " may not be null, use "
+ typeName + "." + defaultName
+ " instead." );
}
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#order(org.neo4j.graphdb.traversal.Order)
*/
public TraversalDescription order( BranchOrderingPolicy selector )
{
if ( this.branchSelector == selector )
{
return this;
}
return new TraversalDescriptionImpl( expander, uniqueness, uniquenessParameter,
evaluator, selector );
}
public TraversalDescription depthFirst()
{
return order( Traversal.preorderDepthFirst() );
}
public TraversalDescription breadthFirst()
{
return order( Traversal.preorderBreadthFirst() );
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#relationships(org.neo4j.graphdb.RelationshipType)
*/
public TraversalDescription relationships( RelationshipType type )
{
return relationships( type, Direction.BOTH );
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#relationships(org.neo4j.graphdb.RelationshipType, org.neo4j.graphdb.Direction)
*/
public TraversalDescription relationships( RelationshipType type,
Direction direction )
{
return expand( expander.add( type, direction ) );
}
/* (non-Javadoc)
* @see org.neo4j.graphdb.traversal.TraversalDescription#expand(org.neo4j.graphdb.RelationshipExpander)
*/
public TraversalDescription expand(RelationshipExpander expander)
{
if ( expander.equals( this.expander ) )
{
return this;
}
return new TraversalDescriptionImpl( Traversal.expander( expander ), uniqueness,
uniquenessParameter, evaluator, branchSelector );
}
private static class WrappedPruneEvaluator implements Evaluator
{
private final PruneEvaluator pruning;
WrappedPruneEvaluator( PruneEvaluator pruning )
{
this.pruning = pruning;
}
public Evaluation evaluate( Path path )
{
// Before the Evaluator, when PruneEvaluator was used individually a PruneEvaluator
// was never called with the start node as argument. This condition mimics that behaviour.
if ( path.length() == 0 )
{
return Evaluation.INCLUDE_AND_CONTINUE;
}
return pruning.pruneAfter( path ) ? Evaluation.INCLUDE_AND_PRUNE : Evaluation.INCLUDE_AND_CONTINUE;
}
}
private static class WrappedFilter implements Evaluator
{
private final Predicate<Path> filter;
WrappedFilter( Predicate<Path> filter )
{
this.filter = filter;
}
public Evaluation evaluate( Path path )
{
return filter.accept( path ) ? Evaluation.INCLUDE_AND_CONTINUE : Evaluation.EXCLUDE_AND_CONTINUE;
}
}
}