Merge pull request graphstream#8 from beltex/chain-generator

Add new ChainGenerator class, add .gitignore, formatting fix for README.rst

.gitignore

@@ -0,0 +1,7 @@
+.settings
+.classpath
+.project
+bin/
+target/
+*.jar
+*.jardesc

README.rst

@@ -20,16 +20,16 @@ Authors
 
 The GraphStream team:
 
-Julien Baudry <[email protected]>
-Antoine Dutot <[email protected]>
-Yoann Pigné <[email protected]> 
-Guilhelm Savin <[email protected]>
+- Julien Baudry <[email protected]>
+- Antoine Dutot <[email protected]>
+- Yoann Pigné <[email protected]> 
+- Guilhelm Savin <[email protected]>
 
 
 Contributors:
 
-Frédéric Guinand <[email protected]>
-Guillaume-Jean Herbiet <[email protected]>
+- Frédéric Guinand <[email protected]>
+- Guillaume-Jean Herbiet <[email protected]>
 
 
 Help

src/org/graphstream/algorithm/generator/ChainGenerator.java

@@ -0,0 +1,157 @@
+/*
+ * Copyright 2006 - 2013
+ *     Stefan Balev     <[email protected]>
+ *     Julien Baudry    <[email protected]>
+ *     Antoine Dutot    <[email protected]>
+ *     Yoann Pigné      <[email protected]>
+ *     Guilhelm Savin   <[email protected]>
+ *
+ * This file is part of GraphStream <http://graphstream-project.org>.
+ *
+ * GraphStream is a library whose purpose is to handle static or dynamic
+ * graph, create them from scratch, file or any source and display them.
+ *
+ * This program is free software distributed under the terms of two licenses, the
+ * CeCILL-C license that fits European law, and the GNU Lesser General Public
+ * License. You can  use, modify and/ or redistribute the software under the terms
+ * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
+ * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
+ * the Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ *
+ * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * The fact that you are presently reading this means that you have had
+ * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
+ */
+package org.graphstream.algorithm.generator;
+
+/**
+ * Generator for a chain graph of any size.
+ *
+ * <p>
+ * This generator creates a chain graph (much like a linked-list). By default,
+ * the graph is directed and doubly linked (much like a doubly linked-list).
+ * That is, each node has an edge to the next node in the chain, and one going
+ * back to the previous (except for the first and last nodes). A loop back edge
+ * can be added such that the last node in the chain has an edge directly back
+ * to the starting node.
+ * </p>
+ *
+ * <h2>Usage</h2>
+ *
+ * <p>
+ * Calling {@link #begin()} will add an initial node with no edges. Each call
+ * to {@link #nextEvents()} will add a new node, connected to the previous node,
+ * in a chain. If the graph is directed and doubly linked, each call will result
+ * in the addition of two new edges, otherwise just a single edge is added. Thus,
+ * if the graph is undirected, then the doubly linked parameter is ignored, and
+ * only single edges are created between nodes.
+ * </p>
+ *
+ * <p>
+ * If you are displaying the graph, directed and doubly-linked chain graphs are
+ * best viewed with the {@code cubic-curve} edge shape CSS property, though it
+ * will require the use of the <b>gs-ui</b> renderer to work.
+ * </p>
+ *
+ * @since 2014
+ */
+public class ChainGenerator extends BaseGenerator {
+
+
+    /**
+     * Used to generate node names
+     */
+    protected int nodeNames = 0;
+
+
+    /**
+     * Create doubly linked nodes. That is, each node will have an extra edge
+     * directed towards the previous node (except for the first and last node).
+     * This does not apply if the graph is undirected.
+     */
+    protected boolean doublyLinked = true;
+
+
+    /**
+     * Create a loop back edge. That is, the last node has an edge looping back
+     * to the starting node.
+     */
+    private boolean loopBack = false;
+
+
+    /**
+     * New chain generator. By default edges are directed, nodes doubly
+     * linked, and there is no loop back edge.
+     */
+    public ChainGenerator() {
+        this(true, true, false);
+    }
+
+
+    /**
+     * New chain generator.
+     *
+     * @param directed Should the edges be directed?
+     * @param doublyLinked Should the nodes be doubly linked?
+     * @param loopBack Should the graph have a loop back edge?
+     */
+    public ChainGenerator(boolean directed, boolean doublyLinked, boolean loopBack) {
+        super(directed, false);
+
+        this.doublyLinked = doublyLinked;
+        this.loopBack = loopBack;
+    }
+
+
+    /**
+     * Add an initial node.
+     *
+     * @see org.graphstream.algorithm.generator.Generator#begin()
+     */
+    public void begin() {
+        addNode(Integer.toString(nodeNames));
+    }
+
+
+    /**
+     * Add a new node (link) in the chain.
+     *
+     * @see org.graphstream.algorithm.generator.Generator#nextEvents()
+     */
+    public boolean nextEvents() {
+        String id_previous = Integer.toString(nodeNames);
+        String id_next = Integer.toString(++nodeNames);
+
+        addNode(id_next);
+        addEdge(null, id_previous, id_next);
+
+        // No point in adding double edge if undirected
+        if (doublyLinked && directed) {
+            addEdge(null, id_next, id_previous);
+        }
+
+        return true;
+    }
+
+
+    /**
+     * If the graph is set to have a loop back edge, this method will add it.
+     *
+     * @see org.graphstream.algorithm.generator.Generator#end()
+     */
+    @Override
+    public void end() {
+        if (loopBack) {
+            addEdge(null, Integer.toString(nodeNames), "0");
+        }
+
+        super.end();
+    }
+}