Java/Collections Data Structure/Graph
A directed graph data structure
<source lang="java">
/*
* JBoss, Home of Professional Open Source * Copyright 2006, Red Hat Middleware LLC, and individual contributors * by the @authors tag. See the copyright.txt in the distribution for a * full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this software; if not, write to the Free * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA, or see the FSF site: http://www.fsf.org. */
import java.util.ArrayList; import java.util.ruparator; import java.util.LinkedList; import java.util.List; /**
* A directed graph data structure. * * @author Scott.Stark@jboss.org * @version $Revision$ * @param <T> */
@SuppressWarnings("unchecked") public class Graph<T> {
/** Color used to mark unvisited nodes */
public static final int VISIT_COLOR_WHITE = 1;
/** Color used to mark nodes as they are first visited in DFS order */
public static final int VISIT_COLOR_GREY = 2;
/** Color used to mark nodes after descendants are completely visited */
public static final int VISIT_COLOR_BLACK = 3;
/** Vector<Vertex> of graph verticies */
private List<Vertex<T>> verticies;
/** Vector<Edge> of edges in the graph */
private List<Edge<T>> edges;
/** The vertex identified as the root of the graph */
private Vertex<T> rootVertex;
/**
* Construct a new graph without any vertices or edges
*/
public Graph() {
verticies = new ArrayList<Vertex<T>>();
edges = new ArrayList<Edge<T>>();
}
/**
* Are there any verticies in the graph
*
* @return true if there are no verticies in the graph
*/
public boolean isEmpty() {
return verticies.size() == 0;
}
/**
* Add a vertex to the graph
*
* @param v
* the Vertex to add
* @return true if the vertex was added, false if it was already in the graph.
*/
public boolean addVertex(Vertex<T> v) {
boolean added = false;
if (verticies.contains(v) == false) {
added = verticies.add(v);
}
return added;
}
/**
* Get the vertex count.
*
* @return the number of verticies in the graph.
*/
public int size() {
return verticies.size();
}
/**
* Get the root vertex
*
* @return the root vertex if one is set, null if no vertex has been set as
* the root.
*/
public Vertex<T> getRootVertex() {
return rootVertex;
}
/**
* Set a root vertex. If root does no exist in the graph it is added.
*
* @param root -
* the vertex to set as the root and optionally add if it does not
* exist in the graph.
*/
public void setRootVertex(Vertex<T> root) {
this.rootVertex = root;
if (verticies.contains(root) == false)
this.addVertex(root);
}
/**
* Get the given Vertex.
*
* @param n
* the index [0, size()-1] of the Vertex to access
* @return the nth Vertex
*/
public Vertex<T> getVertex(int n) {
return verticies.get(n);
}
/**
* Get the graph verticies
*
* @return the graph verticies
*/
public List<Vertex<T>> getVerticies() {
return this.verticies;
}
/**
* Insert a directed, weighted Edge<T> into the graph.
*
* @param from -
* the Edge<T> starting vertex
* @param to -
* the Edge<T> ending vertex
* @param cost -
* the Edge<T> weight/cost
* @return true if the Edge<T> was added, false if from already has this Edge<T>
* @throws IllegalArgumentException
* if from/to are not verticies in the graph
*/
public boolean addEdge(Vertex<T> from, Vertex<T> to, int cost) throws IllegalArgumentException {
if (verticies.contains(from) == false)
throw new IllegalArgumentException("from is not in graph");
if (verticies.contains(to) == false)
throw new IllegalArgumentException("to is not in graph");
Edge<T> e = new Edge<T>(from, to, cost);
if (from.findEdge(to) != null)
return false;
else {
from.addEdge(e);
to.addEdge(e);
edges.add(e);
return true;
}
}
/**
* Insert a bidirectional Edge<T> in the graph
*
* @param from -
* the Edge<T> starting vertex
* @param to -
* the Edge<T> ending vertex
* @param cost -
* the Edge<T> weight/cost
* @return true if edges between both nodes were added, false otherwise
* @throws IllegalArgumentException
* if from/to are not verticies in the graph
*/
public boolean insertBiEdge(Vertex<T> from, Vertex<T> to, int cost)
throws IllegalArgumentException {
return addEdge(from, to, cost) && addEdge(to, from, cost);
}
/**
* Get the graph edges
*
* @return the graph edges
*/
public List<Edge<T>> getEdges() {
return this.edges;
}
/**
* Remove a vertex from the graph
*
* @param v
* the Vertex to remove
* @return true if the Vertex was removed
*/
public boolean removeVertex(Vertex<T> v) {
if (!verticies.contains(v))
return false;
verticies.remove(v);
if (v == rootVertex)
rootVertex = null;
// Remove the edges associated with v
for (int n = 0; n < v.getOutgoingEdgeCount(); n++) {
Edge<T> e = v.getOutgoingEdge(n);
v.remove(e);
Vertex<T> to = e.getTo();
to.remove(e);
edges.remove(e);
}
for (int n = 0; n < v.getIncomingEdgeCount(); n++) {
Edge<T> e = v.getIncomingEdge(n);
v.remove(e);
Vertex<T> predecessor = e.getFrom();
predecessor.remove(e);
}
return true;
}
/**
* Remove an Edge<T> from the graph
*
* @param from -
* the Edge<T> starting vertex
* @param to -
* the Edge<T> ending vertex
* @return true if the Edge<T> exists, false otherwise
*/
public boolean removeEdge(Vertex<T> from, Vertex<T> to) {
Edge<T> e = from.findEdge(to);
if (e == null)
return false;
else {
from.remove(e);
to.remove(e);
edges.remove(e);
return true;
}
}
/**
* Clear the mark state of all verticies in the graph by calling clearMark()
* on all verticies.
*
* @see Vertex#clearMark()
*/
public void clearMark() {
for (Vertex<T> w : verticies)
w.clearMark();
}
/**
* Clear the mark state of all edges in the graph by calling clearMark() on
* all edges.
*/
public void clearEdges() {
for (Edge<T> e : edges)
e.clearMark();
}
/**
* Perform a depth first serach using recursion.
*
* @param v -
* the Vertex to start the search from
* @param visitor -
* the vistor to inform prior to
* @see Visitor#visit(Graph, Vertex)
*/
public void depthFirstSearch(Vertex<T> v, final Visitor<T> visitor) {
VisitorEX<T, RuntimeException> wrapper = new VisitorEX<T, RuntimeException>() {
public void visit(Graph<T> g, Vertex<T> v) throws RuntimeException {
if (visitor != null)
visitor.visit(g, v);
}
};
this.depthFirstSearch(v, wrapper);
}
/**
* Perform a depth first serach using recursion. The search may be cut short
* if the visitor throws an exception.
*
* @param <E>
*
* @param v -
* the Vertex to start the search from
* @param visitor -
* the vistor to inform prior to
* @see Visitor#visit(Graph, Vertex)
* @throws E
* if visitor.visit throws an exception
*/
public <E extends Exception> void depthFirstSearch(Vertex<T> v, VisitorEX<T, E> visitor) throws E {
if (visitor != null)
visitor.visit(this, v);
v.visit();
for (int i = 0; i < v.getOutgoingEdgeCount(); i++) {
Edge<T> e = v.getOutgoingEdge(i);
if (!e.getTo().visited()) {
depthFirstSearch(e.getTo(), visitor);
}
}
}
/**
* Perform a breadth first search of this graph, starting at v.
*
* @param v -
* the search starting point
* @param visitor -
* the vistor whose vist method is called prior to visting a vertex.
*/
public void breadthFirstSearch(Vertex<T> v, final Visitor<T> visitor) {
VisitorEX<T, RuntimeException> wrapper = new VisitorEX<T, RuntimeException>() {
public void visit(Graph<T> g, Vertex<T> v) throws RuntimeException {
if (visitor != null)
visitor.visit(g, v);
}
};
this.breadthFirstSearch(v, wrapper);
}
/**
* Perform a breadth first search of this graph, starting at v. The vist may
* be cut short if visitor throws an exception during a vist callback.
*
* @param <E>
*
* @param v -
* the search starting point
* @param visitor -
* the vistor whose vist method is called prior to visting a vertex.
* @throws E
* if vistor.visit throws an exception
*/
public <E extends Exception> void breadthFirstSearch(Vertex<T> v, VisitorEX<T, E> visitor)
throws E {
LinkedList<Vertex<T>> q = new LinkedList<Vertex<T>>();
q.add(v);
if (visitor != null)
visitor.visit(this, v);
v.visit();
while (q.isEmpty() == false) {
v = q.removeFirst();
for (int i = 0; i < v.getOutgoingEdgeCount(); i++) {
Edge<T> e = v.getOutgoingEdge(i);
Vertex<T> to = e.getTo();
if (!to.visited()) {
q.add(to);
if (visitor != null)
visitor.visit(this, to);
to.visit();
}
}
}
}
/**
* Find the spanning tree using a DFS starting from v.
*
* @param v -
* the vertex to start the search from
* @param visitor -
* visitor invoked after each vertex is visited and an edge is added
* to the tree.
*/
public void dfsSpanningTree(Vertex<T> v, DFSVisitor<T> visitor) {
v.visit();
if (visitor != null)
visitor.visit(this, v);
for (int i = 0; i < v.getOutgoingEdgeCount(); i++) {
Edge<T> e = v.getOutgoingEdge(i);
if (!e.getTo().visited()) {
if (visitor != null)
visitor.visit(this, v, e);
e.mark();
dfsSpanningTree(e.getTo(), visitor);
}
}
}
/**
* Search the verticies for one with name.
*
* @param name -
* the vertex name
* @return the first vertex with a matching name, null if no matches are found
*/
public Vertex<T> findVertexByName(String name) {
Vertex<T> match = null;
for (Vertex<T> v : verticies) {
if (name.equals(v.getName())) {
match = v;
break;
}
}
return match;
}
/**
* Search the verticies for one with data.
*
* @param data -
* the vertex data to match
* @param compare -
* the comparator to perform the match
* @return the first vertex with a matching data, null if no matches are found
*/
public Vertex<T> findVertexByData(T data, Comparator<T> compare) {
Vertex<T> match = null;
for (Vertex<T> v : verticies) {
if (compare.rupare(data, v.getData()) == 0) {
match = v;
break;
}
}
return match;
}
/**
* Search the graph for cycles. In order to detect cycles, we use a modified
* depth first search called a colored DFS. All nodes are initially marked
* white. When a node is encountered, it is marked grey, and when its
* descendants are completely visited, it is marked black. If a grey node is
* ever encountered, then there is a cycle.
*
* @return the edges that form cycles in the graph. The array will be empty if
* there are no cycles.
*/
public Edge<T>[] findCycles() {
ArrayList<Edge<T>> cycleEdges = new ArrayList<Edge<T>>();
// Mark all verticies as white
for (int n = 0; n < verticies.size(); n++) {
Vertex<T> v = getVertex(n);
v.setMarkState(VISIT_COLOR_WHITE);
}
for (int n = 0; n < verticies.size(); n++) {
Vertex<T> v = getVertex(n);
visit(v, cycleEdges);
}
Edge<T>[] cycles = new Edge[cycleEdges.size()];
cycleEdges.toArray(cycles);
return cycles;
}
private void visit(Vertex<T> v, ArrayList<Edge<T>> cycleEdges) {
v.setMarkState(VISIT_COLOR_GREY);
int count = v.getOutgoingEdgeCount();
for (int n = 0; n < count; n++) {
Edge<T> e = v.getOutgoingEdge(n);
Vertex<T> u = e.getTo();
if (u.getMarkState() == VISIT_COLOR_GREY) {
// A cycle Edge<T>
cycleEdges.add(e);
} else if (u.getMarkState() == VISIT_COLOR_WHITE) {
visit(u, cycleEdges);
}
}
v.setMarkState(VISIT_COLOR_BLACK);
}
public String toString() {
StringBuffer tmp = new StringBuffer("Graph[");
for (Vertex<T> v : verticies)
tmp.append(v);
tmp.append("]");
return tmp.toString();
}
} /*
* JBoss, Home of Professional Open Source Copyright 2006, Red Hat Middleware * LLC, and individual contributors by the @authors tag. See the copyright.txt * in the distribution for a full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it under the * terms of the GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1 of the License, or (at your option) * any later version. * * This software is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more * details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA, or see the FSF * site: http://www.fsf.org. */
/**
* A directed, weighted edge in a graph * * @author Scott.Stark@jboss.org * @version $Revision$ * @param <T> */
class Edge<T> {
private Vertex<T> from;
private Vertex<T> to;
private int cost;
private boolean mark;
/**
* Create a zero cost edge between from and to
*
* @param from
* the starting vertex
* @param to
* the ending vertex
*/
public Edge(Vertex<T> from, Vertex<T> to) {
this(from, to, 0);
}
/**
* Create an edge between from and to with the given cost.
*
* @param from
* the starting vertex
* @param to
* the ending vertex
* @param cost
* the cost of the edge
*/
public Edge(Vertex<T> from, Vertex<T> to, int cost) {
this.from = from;
this.to = to;
this.cost = cost;
mark = false;
}
/**
* Get the ending vertex
*
* @return ending vertex
*/
public Vertex<T> getTo() {
return to;
}
/**
* Get the starting vertex
*
* @return starting vertex
*/
public Vertex<T> getFrom() {
return from;
}
/**
* Get the cost of the edge
*
* @return cost of the edge
*/
public int getCost() {
return cost;
}
/**
* Set the mark flag of the edge
*
*/
public void mark() {
mark = true;
}
/**
* Clear the edge mark flag
*
*/
public void clearMark() {
mark = false;
}
/**
* Get the edge mark flag
*
* @return edge mark flag
*/
public boolean isMarked() {
return mark;
}
/**
* String rep of edge
*
* @return string rep with from/to vertex names and cost
*/
public String toString() {
StringBuffer tmp = new StringBuffer("Edge[from: ");
tmp.append(from.getName());
tmp.append(",to: ");
tmp.append(to.getName());
tmp.append(", cost: ");
tmp.append(cost);
tmp.append("]");
return tmp.toString();
}
} /*
* JBoss, Home of Professional Open Source Copyright 2006, Red Hat Middleware * LLC, and individual contributors by the @authors tag. See the copyright.txt * in the distribution for a full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it under the * terms of the GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1 of the License, or (at your option) * any later version. * * This software is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more * details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA, or see the FSF * site: http://www.fsf.org. */
/**
* A named graph vertex with optional data. * * @author Scott.Stark@jboss.org * @version $Revision$ * @param <T> */
@SuppressWarnings("unchecked") class Vertex<T> {
private List<Edge<T>> incomingEdges;
private List<Edge<T>> outgoingEdges;
private String name;
private boolean mark;
private int markState;
private T data;
/**
* Calls this(null, null).
*/
public Vertex() {
this(null, null);
}
/**
* Create a vertex with the given name and no data
*
* @param n
*/
public Vertex(String n) {
this(n, null);
}
/**
* Create a Vertex with name n and given data
*
* @param n -
* name of vertex
* @param data -
* data associated with vertex
*/
public Vertex(String n, T data) {
incomingEdges = new ArrayList<Edge<T>>();
outgoingEdges = new ArrayList<Edge<T>>();
name = n;
mark = false;
this.data = data;
}
/**
* @return the possibly null name of the vertex
*/
public String getName() {
return name;
}
/**
* @return the possibly null data of the vertex
*/
public T getData() {
return this.data;
}
/**
* @param data
* The data to set.
*/
public void setData(T data) {
this.data = data;
}
/**
* Add an edge to the vertex. If edge.from is this vertex, its an outgoing
* edge. If edge.to is this vertex, its an incoming edge. If neither from or
* to is this vertex, the edge is not added.
*
* @param e -
* the edge to add
* @return true if the edge was added, false otherwise
*/
public boolean addEdge(Edge<T> e) {
if (e.getFrom() == this)
outgoingEdges.add(e);
else if (e.getTo() == this)
incomingEdges.add(e);
else
return false;
return true;
}
/**
* Add an outgoing edge ending at to.
*
* @param to -
* the destination vertex
* @param cost
* the edge cost
*/
public void addOutgoingEdge(Vertex<T> to, int cost) {
Edge<T> out = new Edge<T>(this, to, cost);
outgoingEdges.add(out);
}
/**
* Add an incoming edge starting at from
*
* @param from -
* the starting vertex
* @param cost
* the edge cost
*/
public void addIncomingEdge(Vertex<T> from, int cost) {
Edge<T> out = new Edge<T>(this, from, cost);
incomingEdges.add(out);
}
/**
* Check the vertex for either an incoming or outgoing edge mathcing e.
*
* @param e
* the edge to check
* @return true it has an edge
*/
public boolean hasEdge(Edge<T> e) {
if (e.getFrom() == this)
return incomingEdges.contains(e);
else if (e.getTo() == this)
return outgoingEdges.contains(e);
else
return false;
}
/**
* Remove an edge from this vertex
*
* @param e -
* the edge to remove
* @return true if the edge was removed, false if the edge was not connected
* to this vertex
*/
public boolean remove(Edge<T> e) {
if (e.getFrom() == this)
incomingEdges.remove(e);
else if (e.getTo() == this)
outgoingEdges.remove(e);
else
return false;
return true;
}
/**
*
* @return the count of incoming edges
*/
public int getIncomingEdgeCount() {
return incomingEdges.size();
}
/**
* Get the ith incoming edge
*
* @param i
* the index into incoming edges
* @return ith incoming edge
*/
public Edge<T> getIncomingEdge(int i) {
return incomingEdges.get(i);
}
/**
* Get the incoming edges
*
* @return incoming edge list
*/
public List getIncomingEdges() {
return this.incomingEdges;
}
/**
*
* @return the count of incoming edges
*/
public int getOutgoingEdgeCount() {
return outgoingEdges.size();
}
/**
* Get the ith outgoing edge
*
* @param i
* the index into outgoing edges
* @return ith outgoing edge
*/
public Edge<T> getOutgoingEdge(int i) {
return outgoingEdges.get(i);
}
/**
* Get the outgoing edges
*
* @return outgoing edge list
*/
public List getOutgoingEdges() {
return this.outgoingEdges;
}
/**
* Search the outgoing edges looking for an edge whose"s edge.to == dest.
*
* @param dest
* the destination
* @return the outgoing edge going to dest if one exists, null otherwise.
*/
public Edge<T> findEdge(Vertex<T> dest) {
for (Edge<T> e : outgoingEdges) {
if (e.getTo() == dest)
return e;
}
return null;
}
/**
* Search the outgoing edges for a match to e.
*
* @param e -
* the edge to check
* @return e if its a member of the outgoing edges, null otherwise.
*/
public Edge<T> findEdge(Edge<T> e) {
if (outgoingEdges.contains(e))
return e;
else
return null;
}
/**
* What is the cost from this vertext to the dest vertex.
*
* @param dest -
* the destination vertex.
* @return Return Integer.MAX_VALUE if we have no edge to dest, 0 if dest is
* this vertex, the cost of the outgoing edge otherwise.
*/
public int cost(Vertex<T> dest) {
if (dest == this)
return 0;
Edge<T> e = findEdge(dest);
int cost = Integer.MAX_VALUE;
if (e != null)
cost = e.getCost();
return cost;
}
/**
* Is there an outgoing edge ending at dest.
*
* @param dest -
* the vertex to check
* @return true if there is an outgoing edge ending at vertex, false
* otherwise.
*/
public boolean hasEdge(Vertex<T> dest) {
return (findEdge(dest) != null);
}
/**
* Has this vertex been marked during a visit
*
* @return true is visit has been called
*/
public boolean visited() {
return mark;
}
/**
* Set the vertex mark flag.
*
*/
public void mark() {
mark = true;
}
/**
* Set the mark state to state.
*
* @param state
* the state
*/
public void setMarkState(int state) {
markState = state;
}
/**
* Get the mark state value.
*
* @return the mark state
*/
public int getMarkState() {
return markState;
}
/**
* Visit the vertex and set the mark flag to true.
*
*/
public void visit() {
mark();
}
/**
* Clear the visited mark flag.
*
*/
public void clearMark() {
mark = false;
}
/**
* @return a string form of the vertex with in and out edges.
*/
public String toString() {
StringBuffer tmp = new StringBuffer("Vertex(");
tmp.append(name);
tmp.append(", data=");
tmp.append(data);
tmp.append("), in:[");
for (int i = 0; i < incomingEdges.size(); i++) {
Edge<T> e = incomingEdges.get(i);
if (i > 0)
tmp.append(",");
tmp.append("{");
tmp.append(e.getFrom().name);
tmp.append(",");
tmp.append(e.getCost());
tmp.append("}");
}
tmp.append("], out:[");
for (int i = 0; i < outgoingEdges.size(); i++) {
Edge<T> e = outgoingEdges.get(i);
if (i > 0)
tmp.append(",");
tmp.append("{");
tmp.append(e.getTo().name);
tmp.append(",");
tmp.append(e.getCost());
tmp.append("}");
}
tmp.append("]");
return tmp.toString();
}
} /*
* JBoss, Home of Professional Open Source Copyright 2006, Red Hat Middleware * LLC, and individual contributors by the @authors tag. See the copyright.txt * in the distribution for a full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it under the * terms of the GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1 of the License, or (at your option) * any later version. * * This software is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more * details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA, or see the FSF * site: http://www.fsf.org. */
/**
* A graph visitor interface. * * @author Scott.Stark@jboss.org * @version $Revision$ * @param <T> */
interface Visitor<T> {
/** * Called by the graph traversal methods when a vertex is first visited. * * @param g - * the graph * @param v - * the vertex being visited. */ public void visit(Graph<T> g, Vertex<T> v);
} /*
* JBoss, Home of Professional Open Source Copyright 2006, Red Hat Middleware * LLC, and individual contributors by the @authors tag. See the copyright.txt * in the distribution for a full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it under the * terms of the GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1 of the License, or (at your option) * any later version. * * This software is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more * details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA, or see the FSF * site: http://www.fsf.org. */
/**
* A graph visitor interface that can throw an exception during a visit * callback. * * @author Scott.Stark@jboss.org * @version $Revision$ * @param <T> * @param <E> */
interface VisitorEX<T, E extends Exception> {
/** * Called by the graph traversal methods when a vertex is first visited. * * @param g - * the graph * @param v - * the vertex being visited. * @throws E * exception for any error */ public void visit(Graph<T> g, Vertex<T> v) throws E;
} /*
* JBoss, Home of Professional Open Source Copyright 2006, Red Hat Middleware * LLC, and individual contributors by the @authors tag. See the copyright.txt * in the distribution for a full listing of individual contributors. * * This is free software; you can redistribute it and/or modify it under the * terms of the GNU Lesser General Public License as published by the Free * Software Foundation; either version 2.1 of the License, or (at your option) * any later version. * * This software is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more * details. * * You should have received a copy of the GNU Lesser General Public License * along with this software; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA, or see the FSF * site: http://www.fsf.org. */
/**
* A spanning tree visitor callback interface * * @see Graph#dfsSpanningTree(Vertex, DFSVisitor) * * @author Scott.Stark@jboss.org * @version $Revision$ * @param <T> */
interface DFSVisitor<T> {
/** * Called by the graph traversal methods when a vertex is first visited. * * @param g - * the graph * @param v - * the vertex being visited. */ public void visit(Graph<T> g, Vertex<T> v); /** * Used dfsSpanningTree to notify the visitor of each outgoing edge to an * unvisited vertex. * * @param g - * the graph * @param v - * the vertex being visited * @param e - * the outgoing edge from v */ public void visit(Graph<T> g, Vertex<T> v, Edge<T> e);
}
</source>
