/**
* Copyright (c) 2002-2013 "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 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 <http://www.gnu.org/licenses/>.
*/
package org.neo4j.graphdb.traversal;
import org.neo4j.graphdb.Path;
import org.neo4j.helpers.Predicate;
/**
* An Evaluator controls what's to be returned from a traversal and also how
* pruning is done. It looks at a {@link Path} and decides whether or not it
* should be included in the traversal result. It also decides whether the traverser
* should continue down that path or if it should be pruned so that the traverser
* won't continue down that path.
*
* {@link Evaluator} and the corresponding {@link TraversalDescription#evaluator(Evaluator)}
* will replace {@link TraversalDescription#prune(PruneEvaluator)} and
* {@link TraversalDescription#filter(Predicate)} because of the flexibility and
* performance improvements it can provide.
*
* @author Mattias Persson
* @see Evaluation
* @see Evaluators
* @see TraversalDescription#evaluator(Evaluator)
*/
public interface Evaluator
{
/**
* Evaluates a {@link Path} and returns an {@link Evaluation} containing
* information about whether or not to include it in the traversal result,
* i.e return it from the {@link Traverser}. And also whether or not to
* continue traversing down that {@code path} or if it instead should be
* pruned so that the traverser won't continue down that branch represented
* by {@code path}.
*
* @param path the {@link Path} to evaluate.
* @return an {@link Evaluation} containing information about whether or not
* to return it from the {@link Traverser} and whether or not to continue
* down that path.
*/
Evaluation evaluate( Path path );
}