Examples with LiteDepthFirstSelector org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector used on opensource projects

Example 1 with LiteDepthFirstSelector

use of org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector in project neo4j by neo4j.

the class ExactDepthPathFinder method instantiateTraverser.

@Override
protected Traverser instantiateTraverser(Node start, Node end) {
    var transaction = context.transaction();
    TraversalDescription side = transaction.traversalDescription().breadthFirst().uniqueness(uniqueness).order((startSource, expander) -> new LiteDepthFirstSelector(startSource, startThreshold, expander));
    return transaction.bidirectionalTraversalDescription().startSide(side.expand(expander).evaluator(toDepth(onDepth / 2))).endSide(side.expand(expander.reverse()).evaluator(toDepth(onDepth - onDepth / 2))).collisionEvaluator(atDepth(onDepth)).traverse(start, end);
}

Example 2 with LiteDepthFirstSelector

use of org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector 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;
        }
    };
}

Example 3 with LiteDepthFirstSelector

use of org.neo4j.graphalgo.impl.util.LiteDepthFirstSelector 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;
        }
    };
}