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Graph Database API for Neo4j.
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [http://neo4j.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 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see the type of {@link org.neo4j.graphdb.Path}.
*/
public interface PathDescriptor
{
/**
* Returns a string representation of a {@link org.neo4j.graphdb.Node}.
* @param path the {@link Path} we're building a string representation
* from.
* @param node the {@link org.neo4j.graphdb.Node} to return a string representation of.
* @return a string representation of a {@link org.neo4j.graphdb.Node}.
*/
String nodeRepresentation( T path, Node node );
/**
* Returns a string representation of a {@link org.neo4j.graphdb.Relationship}.
* @param path the {@link Path} we're building a string representation
* from.
* @param from the previous {@link Node} in the path.
* @param relationship the {@link org.neo4j.graphdb.Relationship} to return a string
* representation of.
* @return a string representation of a {@link org.neo4j.graphdb.Relationship}.
*/
String relationshipRepresentation( T path, Node from,
Relationship relationship );
}
/**
* The default {@link PathDescriptor} used in common toString()
* representations in classes implementing {@link Path}.
* @param the type of {@link Path}.
*/
public static class DefaultPathDescriptor implements PathDescriptor
{
@Override
public String nodeRepresentation( Path path, Node node )
{
return "(" + node.getId() + ")";
}
@Override
public String relationshipRepresentation( Path path,
Node from, Relationship relationship )
{
String prefix = "-";
String suffix = "-";
if ( from.equals( relationship.getEndNode() ) )
{
prefix = "<-";
}
else
{
suffix = "->";
}
return prefix + "[" + relationship.getType().name() + "," +
relationship.getId() + "]" + suffix;
}
}
/**
* Method for building a string representation of a {@link Path}, using
* the given {@code builder}.
* @param the type of {@link Path}.
* @param path the {@link Path} to build a string representation of.
* @param builder the {@link PathDescriptor} to get
* {@link Node} and {@link Relationship} representations from.
* @return a string representation of a {@link Path}.
*/
public static String pathToString( T path, PathDescriptor builder )
{
Node current = path.startNode();
StringBuilder result = new StringBuilder();
for ( Relationship rel : path.relationships() )
{
result.append( builder.nodeRepresentation( path, current ) );
result.append( builder.relationshipRepresentation( path, current, rel ) );
current = rel.getOtherNode( current );
}
if ( null != current )
{
result.append( builder.nodeRepresentation( path, current ) );
}
return result.toString();
}
/**
* TODO: This method re-binds nodes and relationships. It should not.
*
* Returns the default string representation of a {@link Path}. It uses
* the {@link DefaultPathDescriptor} to get representations.
* @param path the {@link Path} to build a string representation of.
* @return the default string representation of a {@link Path}.
*/
public static String defaultPathToString( Path path )
{
return pathToString( path, new DefaultPathDescriptor<>() );
}
/**
* Returns a quite simple string representation of a {@link Path}. It
* doesn't print relationship types or ids, just directions.
* @param path the {@link Path} to build a string representation of.
* @return a quite simple representation of a {@link Path}.
*/
public static String simplePathToString( Path path )
{
return pathToString( path, new DefaultPathDescriptor<>()
{
@Override
public String relationshipRepresentation( Path path, Node from,
Relationship relationship )
{
return relationship.getStartNode().equals( from ) ? "-->" : "<--";
}
} );
}
/**
* Returns a quite simple string representation of a {@link Path}. It
* doesn't print relationship types or ids, just directions. it uses the
* {@code nodePropertyKey} to try to display that property value as in the
* node representation instead of the node id. If that property doesn't
* exist, the id is used.
* @param path the {@link Path} to build a string representation of.
* @param nodePropertyKey the key of the property value to display
* @return a quite simple representation of a {@link Path}.
*/
public static String simplePathToString( Path path, final String nodePropertyKey )
{
return pathToString( path, new DefaultPathDescriptor<>()
{
@Override
public String nodeRepresentation( Path path, Node node )
{
return "(" + node.getProperty( nodePropertyKey, node.getId() ) + ")";
}
@Override
public String relationshipRepresentation( Path path, Node from,
Relationship relationship )
{
return relationship.getStartNode().equals( from ) ? "-->" : "<--";
}
} );
}
/**
* Create a new {@link Paths.PathDescriptor} that prints values of listed property keys
* and id of nodes and relationships if configured so.
* @param nodeId true if node id should be included.
* @param relId true if relationship id should be included.
* @param propertyKeys all property keys that should be included.
* @param the type of the {@link Path}
* @return a new {@link Paths.PathDescriptor}
*/
public static PathDescriptor descriptorForIdAndProperties( final boolean nodeId,
final boolean relId, final String... propertyKeys )
{
return new Paths.PathDescriptor<>()
{
@Override
public String nodeRepresentation( T path, Node node )
{
String representation = representation( node );
return "(" + (nodeId ? node.getId() : "") +
(nodeId && !representation.equals( "" ) ? "," : "") +
representation + ")";
}
private String representation( Entity entity )
{
StringBuilder builder = new StringBuilder();
for ( String key : propertyKeys )
{
Object value = entity.getProperty( key, null );
if ( value != null )
{
if ( builder.length() > 0 )
{
builder.append( ',' );
}
builder.append( value );
}
}
return builder.toString();
}
@Override
public String relationshipRepresentation( T path, Node from, Relationship relationship )
{
Direction direction = relationship.getEndNode().equals( from ) ? Direction.INCOMING : Direction.OUTGOING;
StringBuilder builder = new StringBuilder();
if ( direction.equals( Direction.INCOMING ) )
{
builder.append( '<' );
}
builder.append( "-[" + (relId ? relationship.getId() : "") );
String representation = representation( relationship );
if ( relId && !representation.equals( "" ) )
{
builder.append( ',' );
}
builder.append( representation );
builder.append( "]-" );
if ( direction.equals( Direction.OUTGOING ) )
{
builder.append( '>' );
}
return builder.toString();
}
};
}
public static Path singleNodePath( Node node )
{
return new SingleNodePath( node );
}
private static class SingleNodePath implements Path
{
private final Node node;
SingleNodePath( Node node )
{
this.node = node;
}
@Override
public Node startNode()
{
return node;
}
@Override
public Node endNode()
{
return node;
}
@Override
public Relationship lastRelationship()
{
return null;
}
@Override
public Iterable relationships()
{
return Collections.emptyList();
}
@Override
public Iterable reverseRelationships()
{
return relationships();
}
@Override
public Iterable nodes()
{
return Arrays.asList( node );
}
@Override
public Iterable reverseNodes()
{
return nodes();
}
@Override
public int length()
{
return 0;
}
@Override
public Iterator iterator()
{
return Arrays.asList( node ).iterator();
}
}
public static String defaultPathToStringWithNotInTransactionFallback( Path path )
{
try
{
return Paths.defaultPathToString( path );
}
catch ( NotInTransactionException | DatabaseShutdownException e )
{
// We don't keep the rel-name lookup if the database is shut down. Source ID and target ID also requires
// database access in a transaction. However, failing on toString would be uncomfortably evil, so we fall
// back to noting the relationship type id.
}
StringBuilder sb = new StringBuilder();
for ( Relationship rel : path.relationships() )
{
if ( sb.length() == 0 )
{
sb.append( "(?)" );
}
sb.append( "-[?," ).append( rel.getId() ).append( "]-(?)" );
}
return sb.toString();
}
}
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