Examples with Evaluator org.neo4j.graphdb.traversal.Evaluator used on opensource projects

Example 1 with Evaluator

use of org.neo4j.graphdb.traversal.Evaluator in project neo4j by neo4j.

the class DijkstraBidirectional method traverser.

private Traverser traverser(Node start, final Node end, PathInterest interest) {
    final MutableDouble shortestSoFar = new MutableDouble(Double.MAX_VALUE);
    final MutableDouble startSideShortest = new MutableDouble(0);
    final MutableDouble endSideShortest = new MutableDouble(0);
    PathExpander dijkstraExpander = new DijkstraBidirectionalPathExpander(expander, shortestSoFar, true, startSideShortest, endSideShortest, epsilon);
    GraphDatabaseService db = start.getGraphDatabase();
    TraversalDescription side = db.traversalDescription().expand(dijkstraExpander, stateFactory).order(new DijkstraSelectorFactory(interest, costEvaluator)).evaluator(new DijkstraBidirectionalEvaluator(costEvaluator)).uniqueness(Uniqueness.NODE_PATH);
    TraversalDescription startSide = side;
    TraversalDescription endSide = side.reverse();
    BidirectionalTraversalDescription traversal = db.bidirectionalTraversalDescription().startSide(startSide).endSide(endSide).collisionEvaluator(Evaluators.all()).collisionPolicy(new BranchCollisionPolicy() {

        @Override
        public BranchCollisionDetector create(Evaluator evaluator, Predicate<Path> pathPredicate) {
            return new DijkstraBranchCollisionDetector(evaluator, costEvaluator, shortestSoFar, epsilon, pathPredicate);
        }
    });
    lastTraverser = traversal.traverse(start, end);
    return lastTraverser;
}

Example 2 with Evaluator

use of org.neo4j.graphdb.traversal.Evaluator in project neo4j by neo4j.

the class TestTraversalWithLoops method traverseThroughNodeWithLoop.

@Test
public void traverseThroughNodeWithLoop() throws Exception {
    /*
         * (a)-->(b)-->(c)-->(d)-->(e)
         *             /  \ /  \
         *             \__/ \__/
         */
    createGraph("a TO b", "b TO c", "c TO c", "c TO d", "d TO d", "d TO e");
    try (Transaction tx = beginTx()) {
        Node a = getNodeWithName("a");
        final Node e = getNodeWithName("e");
        Evaluator onlyEndNode = new Evaluator() {

            @Override
            public Evaluation evaluate(Path path) {
                return Evaluation.ofIncludes(path.endNode().equals(e));
            }
        };
        TraversalDescription basicTraverser = getGraphDb().traversalDescription().evaluator(onlyEndNode);
        expectPaths(basicTraverser.traverse(a), "a,b,c,d,e");
        expectPaths(basicTraverser.uniqueness(Uniqueness.RELATIONSHIP_PATH).traverse(a), "a,b,c,d,e", "a,b,c,c,d,e", "a,b,c,d,d,e", "a,b,c,c,d,d,e");
        tx.success();
    }
}

Example 3 with Evaluator

use of org.neo4j.graphdb.traversal.Evaluator in project neo4j by neo4j.

the class TestBidirectionalTraversal method mirroredTraversalReversesInitialState.

@Test
public void mirroredTraversalReversesInitialState() throws Exception {
    /*
         * (a)-->(b)-->(c)-->(d)
         */
    createGraph("a TO b", "b TO c", "c TO d");
    BranchCollisionPolicy collisionPolicy = new BranchCollisionPolicy() {

        @Override
        public BranchCollisionDetector create(Evaluator evaluator, Predicate<Path> pathPredicate) {
            return new StandardBranchCollisionDetector(null, null) {

                @Override
                protected boolean includePath(Path path, TraversalBranch startPath, TraversalBranch endPath) {
                    assertEquals(0, startPath.state());
                    assertEquals(10, endPath.state());
                    return true;
                }
            };
        }
    };
    Iterables.count(getGraphDb().bidirectionalTraversalDescription().mirroredSides(getGraphDb().traversalDescription().uniqueness(NODE_PATH).expand(PathExpanders.<Integer>forType(to), new InitialBranchState.State<>(0, 10))).collisionPolicy(collisionPolicy).traverse(getNodeWithName("a"), getNodeWithName("d")));
}

Example 4 with Evaluator

use of org.neo4j.graphdb.traversal.Evaluator in project neo4j by neo4j.

the class TestMultipleFilters method testNarrowingFilters.

@Test
public void testNarrowingFilters() {
    Evaluator mustBeConnectedToK = new MustBeConnectedToNodeFilter(getNodeWithName("k"));
    Evaluator mustNotHaveMoreThanTwoOutRels = path -> Evaluation.ofIncludes(Iterables.count(path.endNode().getRelationships(Direction.OUTGOING)) <= 2);
    TraversalDescription description = getGraphDb().traversalDescription().evaluator(mustBeConnectedToK);
    expectNodes(description.traverse(node("a")), "b", "c");
    expectNodes(description.evaluator(mustNotHaveMoreThanTwoOutRels).traverse(node("a")), "c");
}

Example 5 with Evaluator

use of org.neo4j.graphdb.traversal.Evaluator in project graphdb by neo4j-attic.

the class TestMultiPruneEvaluators method testMaxDepthAndCustomPruneEvaluatorCombined.

@Test
public void testMaxDepthAndCustomPruneEvaluatorCombined() {
    Evaluator lessThanThreeRels = new Evaluator() {

        public Evaluation evaluate(Path path) {
            return IteratorUtil.count(path.endNode().getRelationships(Direction.OUTGOING).iterator()) < 3 ? Evaluation.INCLUDE_AND_PRUNE : Evaluation.INCLUDE_AND_CONTINUE;
        }
    };
    TraversalDescription description = Traversal.description().evaluator(Evaluators.all()).evaluator(Evaluators.toDepth(1)).evaluator(lessThanThreeRels);
    Set<String> expectedNodes = new HashSet<String>(Arrays.asList("a", "b", "c", "d", "e"));
    for (Path position : description.traverse(referenceNode())) {
        String name = (String) position.endNode().getProperty("name");
        assertTrue(name + " shouldn't have been returned", expectedNodes.remove(name));
    }
    assertTrue(expectedNodes.isEmpty());
}