Initial revision

git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/sandbox/graph/trunk@144575 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/commons/graph/DFS.java

@@ -0,0 +1,142 @@
+package org.apache.commons.graph;
+
+/* ====================================================================
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2001 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Apache" and "Apache Software Foundation" and
+ *    "Apache BCEL" must not be used to endorse or promote products
+ *    derived from this software without prior written permission. For
+ *    written permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache",
+ *    "Apache BCEL", nor may "Apache" appear in their name, without
+ *    prior written permission of the Apache Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+/**
+ * Visit graph with depth first search and mark discovery and finishing time in all
+ * vertices.
+ *
+ * @version $Id: DFS.java,v 1.1 2001/11/12 16:05:18 jvanzyl Exp $
+ * @author  <A HREF="http://www.inf.fu-berlin.de/~dahm">M. Dahm</A>
+ */
+public class DFS extends TraversalOrder {
+  /**
+   * Depth first search algorithm.
+   *
+   * @param v visitor object to apply when discovering and finishing a vertex or edge
+   */
+  public DFS(Visitor v) {
+    super(v);
+  }
+
+  /**
+   * Depth first search algorithm.
+   *
+   * @param v visitor object to apply when discovering and finishing a vertex or edge
+   * @param traverse_all traverse the complete graph or stop after finishing all nodes reachable
+   * from the start
+   */
+  public DFS(Visitor v, boolean traverse_all) {
+    super(v, traverse_all);
+  }
+
+  /**
+   * Run depth first search (DFS) algorithm.
+   *
+   * @param g graph to traverse
+   * @param start vertex to start at (or null, starts at some vertex then)
+   */
+  public void start(Graph g, Vertex start) {
+    int      size     = g.getNoVertices();
+    Vertex[] vertices = g.getVertexArray();
+
+    graph = g;
+    
+    visitor.discoverGraph(g);
+
+    /* Initially mark all vertices as WHITE
+     */
+    for(int i=0; i < size; i++)
+      vertices[i].setColor(WHITE);
+
+    if(start != null && g.contains(start)) // Start DFS at (white) start vertex
+      DFS_Visit(start);
+
+    if(traverse_complete_graph) {
+      for(int i=0; (i < size) && !stopped; i++) {
+	Vertex v = vertices[i];
+	
+	if(v.getColor() == WHITE) // Unvisited vertex?
+	  DFS_Visit(v);
+      }
+    }
+
+    visitor.finishGraph(g);
+  }
+
+  private final void DFS_Visit(Vertex u) {
+    u.setColor(GRAY);      // Mark as visited
+    visitor.discoverVertex(u);
+
+    Vertex[] vertices = graph.getVertexArray(u); // Get adjacent vertices
+    Edge[]   edges    = graph.getEdgeArray(u);   // and edges
+    int      size     = vertices.length;
+    //System.out.println(java.util.Arrays.asList(edges));
+
+    for(int i=0; (i < size) && !stopped; i++) {     // Explore all edges
+      visitor.discoverEdge(edges[i]);
+
+      Vertex v = vertices[i];
+
+      if(v.getColor() == WHITE)
+	DFS_Visit(v);
+
+      visitor.finishEdge(edges[i]);
+    }
+
+    u.setColor(BLACK);  // Mark as finished
+    visitor.finishVertex(u);
+  }
+}