org.neo4j.kernel
Class Traversal

java.lang.Object
  org.neo4j.kernel.Traversal

public class Traversal
extends Object

A factory for objects regarding traversal of the graph. F.ex. it has a method description() for creating a new TraversalDescription, methods for creating new TraversalBranch instances and more.

Nested Class Summary

static class	Traversal.DefaultPathDescriptor<T extends Path> The default Traversal.PathDescriptor used in common toString() representations in classes implementing Path.
static interface	Traversal.PathDescriptor<T extends Path> Provides hooks to help build a string representation of a Path.

Constructor Summary

Traversal()

Method Summary

static TraversalBranch	combineSourcePaths(TraversalBranch source, TraversalBranch target) Combines two TraversalBranchs with a common head node in order to obtain an TraversalBranch representing a path from the start node of the source TraversalBranch to the start node of the target TraversalBranch.
static String	defaultPathToString(Path path) Returns the default string representation of a Path.
static TraversalDescription	description() Creates a new TraversalDescription with default value for everything so that it's OK to call TraversalDescription.traverse(org.neo4j.graphdb.Node) without modification.
static Expander	emptyExpander() Returns an empty Expander which, if not modified, will expand all relationships when asked to expand a Node.
static Expander	expander(RelationshipExpander expander) Returns a RelationshipExpander wrapped as an Expander.
static Expander	expanderForAllTypes() Returns a RelationshipExpander which expands relationships of all types and directions.
static Expander	expanderForAllTypes(Direction direction) Returns a RelationshipExpander which expands relationships of all types in the given direction.
static Expander	expanderForTypes(RelationshipType type) Creates a new RelationshipExpander which is set to expand relationships with type in any direction.
static Expander	expanderForTypes(RelationshipType type, Direction dir) Creates a new RelationshipExpander which is set to expand relationships with type and direction.
static Expander	expanderForTypes(RelationshipType type1, Direction dir1, RelationshipType type2, Direction dir2) Creates a new RelationshipExpander which is set to expand relationships with two different types and directions.
static Expander	expanderForTypes(RelationshipType type1, Direction dir1, RelationshipType type2, Direction dir2, Object... more) Creates a new RelationshipExpander which is set to expand relationships with multiple types and directions.
static <T extends Path> String	pathToString(T path, Traversal.PathDescriptor<T> builder) Method for building a string representation of a Path, using the given builder.
static BranchOrderingPolicy	postorderBreadthFirst() Returns a "postorder breadth first" ordering policy.
static BranchOrderingPolicy	postorderDepthFirst() Returns a "postorder depth first" ordering policy.
static BranchOrderingPolicy	preorderBreadthFirst() Returns a "preorder breadth first" ordering policy.
static BranchOrderingPolicy	preorderDepthFirst() Returns a "preorder depth first" ordering policy.
static PruneEvaluator	pruneAfterDepth(int depth) Deprecated. because of the introduction of Evaluator. The equivalent is Evaluators.toDepth(int).
static Predicate<Path>	returnAcceptedByAny(Predicate<Path>... filters) Returns a filter which accepts items accepted by at least one of the supplied filters.
static Predicate<Path>	returnAll() Deprecated. because of the introduction of Evaluator. The equivalent is Evaluators.all().
static Predicate<Path>	returnAllButStartNode() Deprecated. because of the introduction of Evaluator. The equivalent is Evaluators.excludeStartPosition().
static Predicate<Path>	returnWhereLastRelationshipTypeIs(RelationshipType firstRelationshipType, RelationshipType... relationshipTypes)
static String	simplePathToString(Path path) Returns a quite simple string representation of a Path.
static String	simplePathToString(Path path, String nodePropertyKey) Returns a quite simple string representation of a Path.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Traversal

public Traversal()

Method Detail

description

public static TraversalDescription description()

Creates a new TraversalDescription with default value for everything so that it's OK to call TraversalDescription.traverse(org.neo4j.graphdb.Node) without modification. But it isn't a very useful traversal, instead you should add rules and behaviours to it before traversing.

Returns:

a new TraversalDescription with default values.

expanderForTypes

public static Expander expanderForTypes(RelationshipType type,
                                        Direction dir)

Creates a new RelationshipExpander which is set to expand relationships with type and direction.

Parameters:

type - the RelationshipType to expand.

dir - the Direction to expand.

Returns:

a new RelationshipExpander.

expanderForTypes

public static Expander expanderForTypes(RelationshipType type)

Creates a new RelationshipExpander which is set to expand relationships with type in any direction.

Parameters:

type - the RelationshipType to expand.

Returns:

a new RelationshipExpander.

emptyExpander

public static Expander emptyExpander()

Returns an empty Expander which, if not modified, will expand all relationships when asked to expand a Node. Criterias can be added to narrow the Expansion.

Returns:

an empty Expander which, if not modified, will expand all relationship for Nodes.

expanderForTypes

public static Expander expanderForTypes(RelationshipType type1,
                                        Direction dir1,
                                        RelationshipType type2,
                                        Direction dir2)

Creates a new RelationshipExpander which is set to expand relationships with two different types and directions.

Parameters:

type1 - a RelationshipType to expand.

dir1 - a Direction to expand.

type2 - another RelationshipType to expand.

dir2 - another Direction to expand.

Returns:

a new RelationshipExpander.

expanderForTypes

public static Expander expanderForTypes(RelationshipType type1,
                                        Direction dir1,
                                        RelationshipType type2,
                                        Direction dir2,
                                        Object... more)

Creates a new RelationshipExpander which is set to expand relationships with multiple types and directions.

Parameters:

type1 - a RelationshipType to expand.

dir1 - a Direction to expand.

type2 - another RelationshipType to expand.

dir2 - another Direction to expand.

more - additional pairs or type/direction to expand.

Returns:

a new RelationshipExpander.

expanderForAllTypes

public static Expander expanderForAllTypes()

Returns a RelationshipExpander which expands relationships of all types and directions.

Returns:

a relationship expander which expands all relationships.

expanderForAllTypes

public static Expander expanderForAllTypes(Direction direction)

Returns a RelationshipExpander which expands relationships of all types in the given direction.

Returns:

a relationship expander which expands all relationships in the given direction.

expander

public static Expander expander(RelationshipExpander expander)

Returns a RelationshipExpander wrapped as an Expander.

Parameters:

expander - RelationshipExpander to wrap.

Returns:

a RelationshipExpander wrapped as an Expander.

combineSourcePaths

public static TraversalBranch combineSourcePaths(TraversalBranch source,
                                                 TraversalBranch target)

Combines two TraversalBranchs with a common head node in order to obtain an TraversalBranch representing a path from the start node of the source TraversalBranch to the start node of the target TraversalBranch. The resulting TraversalBranch will not expand further, and does not provide a parent TraversalBranch.

Parameters:

source - the TraversalBranch where the resulting path starts

target - the TraversalBranch where the resulting path ends

Returns:

an TraversalBranch that represents the path from the start node of the source TraversalBranch to the start node of the target TraversalBranch

Throws:

IllegalArgumentException - if the head nodes of the supplied TraversalBranchs does not match

pruneAfterDepth

public static PruneEvaluator pruneAfterDepth(int depth)

Deprecated. because of the introduction of Evaluator. The equivalent is Evaluators.toDepth(int).

A PruneEvaluator which prunes everything beyond depth.

Parameters:

depth - the depth to prune beyond (after).

Returns:

a PruneEvaluator which prunes everything after depth.

returnAll

public static Predicate<Path> returnAll()

Deprecated. because of the introduction of Evaluator. The equivalent is Evaluators.all().

A traversal return filter which returns all Paths it encounters.

Returns:

a return filter which returns everything.

returnAcceptedByAny

public static Predicate<Path> returnAcceptedByAny(Predicate<Path>... filters)

Returns a filter which accepts items accepted by at least one of the supplied filters.

Parameters:

filters - to group together.

Returns:

a Predicate which accepts if any of the filters accepts.

returnAllButStartNode

public static Predicate<Path> returnAllButStartNode()

Deprecated. because of the introduction of Evaluator. The equivalent is Evaluators.excludeStartPosition().

A traversal return filter which returns all Paths except the position of the start node.

Returns:

a return filter which returns everything except the start node.

preorderDepthFirst

public static BranchOrderingPolicy preorderDepthFirst()

Returns a "preorder depth first" ordering policy. A depth first selector always tries to select positions (from the current position) which are deeper than the current position.

Returns:

a BranchOrderingPolicy for a preorder depth first selector.

postorderDepthFirst

public static BranchOrderingPolicy postorderDepthFirst()

Returns a "postorder depth first" ordering policy. A depth first selector always tries to select positions (from the current position) which are deeper than the current position. A postorder depth first selector selects deeper position before the shallower ones.

Returns:

a BranchOrderingPolicy for a postorder depth first selector.

preorderBreadthFirst

public static BranchOrderingPolicy preorderBreadthFirst()

Returns a "preorder breadth first" ordering policy. A breadth first selector always selects all positions on the current depth before advancing to the next depth.

Returns:

a BranchOrderingPolicy for a preorder breadth first selector.

postorderBreadthFirst

public static BranchOrderingPolicy postorderBreadthFirst()

Returns a "postorder breadth first" ordering policy. A breadth first selector always selects all positions on the current depth before advancing to the next depth. A postorder breadth first selector selects the levels in the reversed order, starting with the deepest.

Returns:

a BranchOrderingPolicy for a postorder breadth first selector.

pathToString

public static <T extends Path> String pathToString(T path,
                                                   Traversal.PathDescriptor<T> builder)

Method for building a string representation of a Path, using the given builder.

Type Parameters:

T - the type of Path.

Parameters:

path - the Path to build a string representation of.

builder - the Traversal.PathDescriptor to get Node and Relationship representations from.

Returns:

a string representation of a Path.

defaultPathToString

public static String defaultPathToString(Path path)

Returns the default string representation of a Path. It uses the Traversal.DefaultPathDescriptor to get representations.

Parameters:

path - the Path to build a string representation of.

Returns:

the default string representation of a Path.

simplePathToString

public static String simplePathToString(Path path)

Returns a quite simple string representation of a Path. It doesn't print relationship types or ids, just directions.

Parameters:

path - the Path to build a string representation of.

Returns:

a quite simple representation of a Path.

simplePathToString

public static String simplePathToString(Path path,
                                        String nodePropertyKey)

Returns a quite simple string representation of a Path. It doesn't print relationship types or ids, just directions. it uses the 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.

Parameters:

path - the Path to build a string representation of.

Returns:

a quite simple representation of a Path.

returnWhereLastRelationshipTypeIs

public static Predicate<Path> returnWhereLastRelationshipTypeIs(RelationshipType firstRelationshipType,
                                                                RelationshipType... relationshipTypes)