Search in sources :

Example 26 with Traverser

use of org.neo4j.graphdb.traversal.Traverser in project neo4j-mobile-android by neo4j-contrib.

the class ExactDepthPathFinder method paths.

private Iterator<Path> paths(final Node start, final Node end) {
    TraversalDescription base = Traversal.description().uniqueness(Uniqueness.RELATIONSHIP_PATH).order(new BranchOrderingPolicy() {

        public BranchSelector create(TraversalBranch startSource) {
            return new LiteDepthFirstSelector(startSource, startThreshold);
        }
    });
    final int firstHalf = onDepth / 2;
    Traverser startTraverser = base.prune(Traversal.pruneAfterDepth(firstHalf)).expand(expander).filter(new Predicate<Path>() {

        public boolean accept(Path item) {
            return item.length() == firstHalf;
        }
    }).traverse(start);
    final int secondHalf = onDepth - firstHalf;
    Traverser endTraverser = base.prune(Traversal.pruneAfterDepth(secondHalf)).expand(expander.reversed()).filter(new Predicate<Path>() {

        public boolean accept(Path item) {
            return item.length() == secondHalf;
        }
    }).traverse(end);
    final Iterator<Path> startIterator = startTraverser.iterator();
    final Iterator<Path> endIterator = endTraverser.iterator();
    final Map<Node, Visit> visits = new HashMap<Node, Visit>();
    return new PrefetchingIterator<Path>() {

        @Override
        protected Path fetchNextOrNull() {
            Path[] found = null;
            while (found == null && (startIterator.hasNext() || endIterator.hasNext())) {
                found = goOneStep(start, startIterator, visits);
                if (found == null) {
                    found = goOneStep(end, endIterator, visits);
                }
            }
            return found != null ? toPath(found, start) : null;
        }
    };
}
Also used : Path(org.neo4j.graphdb.Path) PrefetchingIterator(org.neo4j.helpers.collection.PrefetchingIterator) BranchOrderingPolicy(org.neo4j.graphdb.traversal.BranchOrderingPolicy) HashMap(java.util.HashMap) Node(org.neo4j.graphdb.Node) BranchSelector(org.neo4j.graphdb.traversal.BranchSelector) Predicate(org.neo4j.helpers.Predicate) Traverser(org.neo4j.graphdb.traversal.Traverser) TraversalDescription(org.neo4j.graphdb.traversal.TraversalDescription) LiteDepthFirstSelector(org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector) TraversalBranch(org.neo4j.graphdb.traversal.TraversalBranch)

Example 27 with Traverser

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

the class ExactDepthPathFinder method paths.

private Iterator<Path> paths(final Node start, final Node end) {
    TraversalDescription base = Traversal.description().uniqueness(Uniqueness.RELATIONSHIP_PATH).order(new BranchOrderingPolicy() {

        public BranchSelector create(TraversalBranch startSource) {
            return new LiteDepthFirstSelector(startSource, startThreshold);
        }
    });
    final int firstHalf = onDepth / 2;
    Traverser startTraverser = base.prune(Traversal.pruneAfterDepth(firstHalf)).expand(expander).filter(new Predicate<Path>() {

        public boolean accept(Path item) {
            return item.length() == firstHalf;
        }
    }).traverse(start);
    final int secondHalf = onDepth - firstHalf;
    Traverser endTraverser = base.prune(Traversal.pruneAfterDepth(secondHalf)).expand(expander.reversed()).filter(new Predicate<Path>() {

        public boolean accept(Path item) {
            return item.length() == secondHalf;
        }
    }).traverse(end);
    final Iterator<Path> startIterator = startTraverser.iterator();
    final Iterator<Path> endIterator = endTraverser.iterator();
    final Map<Node, Visit> visits = new HashMap<Node, Visit>();
    return new PrefetchingIterator<Path>() {

        @Override
        protected Path fetchNextOrNull() {
            Path[] found = null;
            while (found == null && (startIterator.hasNext() || endIterator.hasNext())) {
                found = goOneStep(start, startIterator, visits);
                if (found == null) {
                    found = goOneStep(end, endIterator, visits);
                }
            }
            return found != null ? toPath(found, start) : null;
        }
    };
}
Also used : Path(org.neo4j.graphdb.Path) PrefetchingIterator(org.neo4j.helpers.collection.PrefetchingIterator) BranchOrderingPolicy(org.neo4j.graphdb.traversal.BranchOrderingPolicy) HashMap(java.util.HashMap) Node(org.neo4j.graphdb.Node) BranchSelector(org.neo4j.graphdb.traversal.BranchSelector) Predicate(org.neo4j.helpers.Predicate) Traverser(org.neo4j.graphdb.traversal.Traverser) TraversalDescription(org.neo4j.graphdb.traversal.TraversalDescription) LiteDepthFirstSelector(org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector) TraversalBranch(org.neo4j.graphdb.traversal.TraversalBranch)

Example 28 with Traverser

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

the class ExperimentalAStar method findAllPaths.

public Iterable<WeightedPath> findAllPaths(Node start, final Node end) {
    Predicate<Path> filter = new Predicate<Path>() {

        public boolean accept(Path position) {
            return position.endNode().equals(end);
        }
    };
    final Traverser traverser = traversalDescription.order(new SelectorFactory(end)).filter(filter).traverse(start);
    return new Iterable<WeightedPath>() {

        public Iterator<WeightedPath> iterator() {
            return new StopAfterWeightIterator(traverser.iterator(), costEvaluator);
        }
    };
}
Also used : Path(org.neo4j.graphdb.Path) WeightedPath(org.neo4j.graphalgo.WeightedPath) WeightedPath(org.neo4j.graphalgo.WeightedPath) BestFirstSelectorFactory(org.neo4j.graphalgo.impl.util.BestFirstSelectorFactory) Traverser(org.neo4j.graphdb.traversal.Traverser) StopAfterWeightIterator(org.neo4j.graphalgo.impl.util.StopAfterWeightIterator) Predicate(org.neo4j.helpers.Predicate)

Example 29 with Traverser

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

the class SmallestGraphEverTest method execute.

private void execute(TraversalDescription traversal, Uniqueness uniqueness) {
    Traverser traverser = traversal.uniqueness(uniqueness).traverse(referenceNode());
    assertFalse("empty traversal", IteratorUtil.count(traverser) == 0);
}
Also used : Traverser(org.neo4j.graphdb.traversal.Traverser)

Example 30 with Traverser

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

the class DepthPitfallGraphTest method testAllRelationshipsAreReturnedOnce.

private void testAllRelationshipsAreReturnedOnce(TraversalDescription description) throws Exception {
    Traverser traverser = Traversal.description().uniqueness(Uniqueness.RELATIONSHIP_GLOBAL).traverse(referenceNode());
    expectRelationships(traverser, THE_WORLD_AS_WE_KNOW_IT);
}
Also used : Traverser(org.neo4j.graphdb.traversal.Traverser)

Aggregations

Traverser (org.neo4j.graphdb.traversal.Traverser)44 Test (org.junit.Test)19 Path (org.neo4j.graphdb.Path)15 Transaction (org.neo4j.graphdb.Transaction)10 HashSet (java.util.HashSet)6 Node (org.neo4j.graphdb.Node)6 Predicate (org.neo4j.helpers.Predicate)6 Set (java.util.Set)4 Stack (java.util.Stack)4 WeightedPath (org.neo4j.graphalgo.WeightedPath)4 BestFirstSelectorFactory (org.neo4j.graphalgo.impl.util.BestFirstSelectorFactory)4 StopAfterWeightIterator (org.neo4j.graphalgo.impl.util.StopAfterWeightIterator)4 Relationship (org.neo4j.graphdb.Relationship)3 ArrayList (java.util.ArrayList)2 HashMap (java.util.HashMap)2 LiteDepthFirstSelector (org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector)2 BranchOrderingPolicy (org.neo4j.graphdb.traversal.BranchOrderingPolicy)2 BranchSelector (org.neo4j.graphdb.traversal.BranchSelector)2 TraversalBranch (org.neo4j.graphdb.traversal.TraversalBranch)2 TraversalDescription (org.neo4j.graphdb.traversal.TraversalDescription)2