com.googlecode.concurrenttrees.radix.node.concrete.charsequence
Class CharSequenceNodeDefault

java.lang.Object
  com.googlecode.concurrenttrees.radix.node.concrete.charsequence.CharSequenceNodeDefault

All Implemented Interfaces:

Node, NodeCharacterProvider

public class CharSequenceNodeDefault
extends Object
implements Node

A implementation of the Node interface which stores the incoming edge as a CharSequence (a view onto the original key) rather than copying the edge into a character array. Stores all variables and supports all behaviours required by the tree, but still could be more memory efficient.

See NodeFactory for documentation on how alternative node implementations can be created to reduce memory overhead. See the Node interface for details on how to write memory-efficient nodes.

This implementation stores references to child nodes in an AtomicReferenceArray, in ascending sorted order of the first character of the edges which child nodes define.

The getOutgoingEdge(Character) method uses binary search to locate a requested node, given the first character of an edge indicated. The node is then read and returned atomically from the AtomicReferenceArray.

The updateOutgoingEdge(com.googlecode.concurrenttrees.radix.node.Node) method ensures that any attempt to update a reference to a child node preserves the constraints defined in the Node interface. New child nodes are written atomically to the AtomicReferenceArray.

The constraints defined in the Node interface ensure that the AtomicReferenceArray always remains in ascending sorted order regardless of modifications performed concurrently, as long as the modifications comply with the constraints. This node enforces those constraints.

Author:

Niall Gallagher

Constructor Summary

CharSequenceNodeDefault(CharSequence edgeCharSequence, Object value, List<Node> outgoingEdges)

Method Summary

CharSequence	getIncomingEdge() Returns all characters of the "edge" encoded in this node, belonging to the connection from a parent node to this node.
Character	getIncomingEdgeFirstCharacter() Returns the first character of the "edge" encoded in this node, belonging to the connection from a parent node to this node.
Node	getOutgoingEdge(Character edgeFirstCharacter) Returns the child of this node whose edge starts with the given first character.
List<Node>	getOutgoingEdges() Returns a read-only list of the child nodes to which this node has outgoing edges, i.e.
Object	getValue() Returns a value object which has been associated with a key and which is stored in this node, or returns null if no value is stored in this node.
String	toString()
void	updateOutgoingEdge(Node childNode) Updates the child node reference for a given edge (identified by its first character) to point to a different child node.

Methods inherited from class java.lang.Object

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

Constructor Detail

CharSequenceNodeDefault

public CharSequenceNodeDefault(CharSequence edgeCharSequence,
                               Object value,
                               List<Node> outgoingEdges)

Method Detail

getIncomingEdge

public CharSequence getIncomingEdge()

Description copied from interface: Node

Returns all characters of the "edge" encoded in this node, belonging to the connection from a parent node to this node.

Specified by:

getIncomingEdge in interface Node

Returns:

All characters of the "edge" encoded in this node

getIncomingEdgeFirstCharacter

public Character getIncomingEdgeFirstCharacter()

Description copied from interface: Node

Returns the first character of the "edge" encoded in this node, belonging to the connection from a parent node to this node.

Specified by:

getIncomingEdgeFirstCharacter in interface Node

Specified by:

getIncomingEdgeFirstCharacter in interface NodeCharacterProvider

Returns:

The first character of the "edge" encoded in this node

getValue

public Object getValue()

Description copied from interface: Node

Returns a value object which has been associated with a key and which is stored in this node, or returns null if no value is stored in this node.

Specified by:

getValue in interface Node

Returns:

A value object which has been associated with a key and which is stored in this node, or returns null if no value is stored in this node

getOutgoingEdge

public Node getOutgoingEdge(Character edgeFirstCharacter)

Description copied from interface: Node

Returns the child of this node whose edge starts with the given first character.

This read must be performed atomically, in relation to writes made via Node.updateOutgoingEdge(Node).

Specified by:

getOutgoingEdge in interface Node

Parameters:

edgeFirstCharacter - The first character of the edge for which the associated child node is required

Returns:

The child of this node whose edge starts with the given first character, or null if this node has no such outgoing edge

updateOutgoingEdge

public void updateOutgoingEdge(Node childNode)

Description copied from interface: Node

Updates the child node reference for a given edge (identified by its first character) to point to a different child node.

The first character of the given child node's edge must match the first character of an existing outgoing edge from this node.

This write must be performed atomically, in relation to reads made via Node.getOutgoingEdge(Character).

Specified by:

updateOutgoingEdge in interface Node

Parameters:

childNode - The new child node to associated with this edge

getOutgoingEdges

public List<Node> getOutgoingEdges()

Description copied from interface: Node

Returns a read-only list of the child nodes to which this node has outgoing edges, i.e. child nodes which have incoming edges from this node.

It is intended that this method will be used for copying/cloning nodes.

Specified by:

getOutgoingEdges in interface Node

Returns:

A read-only list of the child nodes to which this node has outgoing edges

toString

public String toString()

Overrides:

toString in class Object