diva.pod.lwgraph

Class Topology

java.lang.Object

diva.pod.lwgraph.Topology

public final class Topology
extends Object

The primitive data structure underlying a light-weight graph. Clients can instantiate and use this class directly if they don't mind dealing with integer indices to represent nodes and edges. Doing so is recommended only if large graphs are being constructed with no need for information attached to the nodes and/or edges. Note that very little error checking is performed in this class. If information needs to be attached to nodes or edges, then the LightweightGraph class is recommended instead.

Version:

$Revision: 1.4 $

Author:

John Reekie

Constructor Summary

Constructors

Constructor and Description
Topology() Create a new, empty, topology

Method Summary

Modifier and Type	Method and Description
void	connect(int edge, int tail, int head) Connect the tail and head nodes, using the given edge id.
int	find(int firstedge, int tail, int head) Find an edge between the given tail and head nodes, starting from the given edge.
int	getHead(int edge) Get the head node of the given edge.
int	getMaxEdgeId() Get the maximum edge id.
int	getMaxNodeId() Get the highest node id known
int	getTail(int edge) Get the tail node of the given edge.
void	removeEdge(int edge) Remove the given edge.
void	reverse() Reverse the graph
void	setHead(int edge, int head) Set the head node of the given edge.
void	setTail(int edge, int tail) Set the tail node.

Methods inherited from class java.lang.Object

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

Constructor Detail

Topology

public Topology()

Create a new, empty, topology

Method Detail

connect

public void connect(int edge,
                    int tail,
                    int head)

Connect the tail and head nodes, using the given edge id. The amount is storage used by this class depends on the maximum edge id, so edge ids should be alloctated by the caller from zero on up, if possible. More than one edge between two nodes is allowed. If an edge is to be connected at one end only, use an id of -1 for the other end.

find

public int find(int firstedge,
                int tail,
                int head)

Find an edge between the given tail and head nodes, starting from the given edge. Return -1 if none is found.

getMaxEdgeId

public int getMaxEdgeId()

Get the maximum edge id.

getHead

public int getHead(int edge)

Get the head node of the given edge.

getMaxNodeId

public int getMaxNodeId()

Get the highest node id known

getTail

public int getTail(int edge)

Get the tail node of the given edge.

removeEdge

public void removeEdge(int edge)

Remove the given edge.

reverse

public void reverse()

Reverse the graph

setHead

public void setHead(int edge,
                    int head)

Set the head node of the given edge. The edge and node *must* have already been introduced to the graph with the connect() method. The node id can be -1 to "disconnect" the edge.

setTail

public void setTail(int edge,
                    int tail)

Set the tail node. The edge and node *must* have already been introduced to the graph with the connect() method. The node id can be -1 to "disconnect" the edge.