salvo.jesus.graph

Class GraphUtil

java.lang.Object

salvo.jesus.graph.GraphUtil

public class GraphUtil
extends Object

Graph-level utility functions. This is a class with all static methods for utilities that aren't quite big enough to deserve their own classes, and aren't commonly used enough to merit becoming part of one of the Graph interfaces.

Version:

$Id: GraphUtil.java,v 1.1 2002/08/23 04:03:43 jmsalvo Exp $

Author:

jvs@radik.com

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	GraphUtil.EdgeContractionRule EdgeContractionRule is a callback for the contractVertices method.

Constructor Summary

Constructors

Constructor and Description
GraphUtil()

Method Summary

Modifier and Type	Method and Description
static void	addEdge(Graph g, Edge e) Add an Edge to a Graph, converting Exceptions into RuntimeExceptions.
static void	addEdge(Graph g, Vertex v1, Vertex v2) Add an edge to a Graph, converting Exceptions into RuntimeExceptions.
static void	addVertex(Graph g, Vertex v) Add a Vertex to a Graph, converting Exceptions into RuntimeExceptions.
static void	contractVertices(Graph g, Vertex vRemain, Vertex vRemove, GraphUtil.EdgeContractionRule rule) Contract two vertices within a graph.
static boolean	detectCycles(DirectedGraph graph)
static void	mergeInto(Graph gDst, Graph gSrc) Merge two graphs.
static void	removeEdge(Graph g, Edge e) Remove an Edge from a Graph, converting Exceptions into RuntimeExceptions.
static void	removeVertex(Graph g, Vertex v) Remove a Vertex from a Graph, converting Exceptions into RuntimeExceptions.

Methods inherited from class java.lang.Object

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

Constructor Detail

GraphUtil

public GraphUtil()

Method Detail

mergeInto

public static void mergeInto(Graph gDst,
                             Graph gSrc)

Merge two graphs. The result is disconnected. The results are undefined if the two graphs already share Vertices. (Note that if Graph Vertex and Edge collections were Sets instead, this would not be the case; the result would be the connected union of the two graphs.)

Parameters:

gDst - one of the inputs, and also the output (receives the merged result)

gSrc - the other input (unmodified by this operation)

addVertex

public static void addVertex(Graph g,
                             Vertex v)

Add a Vertex to a Graph, converting Exceptions into RuntimeExceptions. For use when you know this operation cannot possibly result in an Exception, and don't want to litter your code with try/catch everywhere you modify a Graph.

Parameters:

g - the graph to be updated

v - the vertex to add

addEdge

public static void addEdge(Graph g,
                           Edge e)

Add an Edge to a Graph, converting Exceptions into RuntimeExceptions. For use when you know this operation cannot possibly result in an Exception, and don't want to litter your code with try/catch everywhere you modify a Graph.

Parameters:

g - the graph to be updated

e - the edge to add

addEdge

public static void addEdge(Graph g,
                           Vertex v1,
                           Vertex v2)

Add an edge to a Graph, converting Exceptions into RuntimeExceptions. For use when you know this operation cannot possibly result in an Exception, and don't want to litter your code with try/catch everywhere you modify a Graph.

Parameters:

g - the graph to be updated

v1 - one of the vertices (the source if g is a DirectedGraph)

v2 - the other vertex (the sink if g is a DirectedGraph)

removeVertex

public static void removeVertex(Graph g,
                                Vertex v)

Remove a Vertex from a Graph, converting Exceptions into RuntimeExceptions. For use when you know this operation cannot possibly result in an Exception, and don't want to litter your code with try/catch everywhere you modify a Graph.

Parameters:

g - the graph to be updated

v - the vertex to remove

removeEdge

public static void removeEdge(Graph g,
                              Edge e)

Remove an Edge from a Graph, converting Exceptions into RuntimeExceptions. For use when you know this operation cannot possibly result in an Exception, and don't want to litter your code with try/catch everywhere you modify a Graph.

Parameters:

g - the graph to be updated

e - the edge to remove

contractVertices

public static void contractVertices(Graph g,
                                    Vertex vRemain,
                                    Vertex vRemove,
                                    GraphUtil.EdgeContractionRule rule)

Contract two vertices within a graph. The vertices need not be already connected.

Parameters:

g - the graph containing the vertices

vRemain - the vertex which will remain in the graph after contraction

vRemove - the other vertex which will be removed as a result of the contraction

rule - callback object used to decide how to deal with edges; if null, no edges are treated as self-loops, and the graph's factory is used for cloning edges

detectCycles

public static boolean detectCycles(DirectedGraph graph)

Returns:

true if the given DirectedGraph contains any cycles