Added basic graph functionality as a first step towards simplifying the container...

[utils] / system / general / src / main / java / org / wamblee / system / graph / Graph.java

diff --git a/system/general/src/main/java/org/wamblee/system/graph/Graph.java b/system/general/src/main/java/org/wamblee/system/graph/Graph.java
new file mode 100644 (file)
index 0000000..5d6e6cc
--- /dev/null
+++ b/system/general/src/main/java/org/wamblee/system/graph/Graph.java
@@ -0,0 +1,138 @@
+/*
+ * Copyright 2008 the original author or authors.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.wamblee.system.graph;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Graph {
+
+    private List<Node> _nodes;
+    private List<Edge> _edges;
+
+    public Graph() {
+        _nodes = new ArrayList<Node>();
+        _edges = new ArrayList<Edge>();
+    }
+
+    public void addNode(Node aNode) {
+        if (_nodes.contains(aNode)) {
+            throw new IllegalArgumentException("Node '" + aNode.getName()
+                    + "' already exists");
+        }
+        _nodes.add(aNode);
+    }
+    
+    public Node findNode(String aName) { 
+        for (Node node: _nodes) { 
+            if ( node.getName().equals(aName)) { 
+                return node; 
+            }
+        }
+        return null; 
+    }
+
+    public boolean removeNode(Node aNode) {
+        if (!findOutgoing(aNode).isEmpty() || !findIncoming(aNode).isEmpty()) {
+            throw new IllegalArgumentException("Cannot remove node '"
+                    + aNode.getName()
+                    + "' because it is connected to one or more edges");
+        }
+        return _nodes.remove(aNode);
+    }
+
+    public void addNodes(List<Node> aNodes) {
+        for (Node node : aNodes) {
+            addNode(node);
+        }
+    }
+
+    public void addEdge(Edge aEdge) {
+        if (_edges.contains(aEdge)) {
+            throw new IllegalArgumentException("Edge '" + aEdge
+                    + "' already exists");
+        }
+        if (!_nodes.contains(aEdge.getFrom())) {
+            throw new IllegalArgumentException("From node '" + aEdge.getFrom()
+                    + "' from edge '" + aEdge + "' is not part of the graph");
+        }
+        if (!_nodes.contains(aEdge.getTo())) {
+            throw new IllegalArgumentException("To node '" + aEdge.getTo()
+                    + "' from edge '" + aEdge + "' is not part of the graph");
+        }
+        _edges.add(aEdge);
+    }
+
+    public boolean removeEdge(Edge aEdge) {
+        return _edges.remove(aEdge);
+    }
+
+    public void addEdges(List<Edge> aEdges) {
+        for (Edge edge : aEdges) {
+            addEdge(edge);
+        }
+    }
+
+    public List<Node> getNodes() {
+        return new ArrayList<Node>(_nodes);
+    }
+
+    public List<Edge> getEdges() {
+        return new ArrayList<Edge>(_edges);
+    }
+
+    public void extend(EdgeFactory aFactory) {
+        for (Node from : _nodes) {
+            for (Node to : _nodes) {
+                _edges.addAll(aFactory.create(from, to));
+            }
+        }
+    }
+
+    public List<Edge> findOutgoing(Node aNode) {
+        List<Edge> result = new ArrayList<Edge>();
+        for (Edge edge : _edges) {
+            if (edge.getFrom().getName().equals(aNode.getName())) {
+                result.add(edge);
+            }
+        }
+        return result;
+    }
+
+    public List<Edge> findIncoming(Node aNode) {
+        List<Edge> result = new ArrayList<Edge>();
+        for (Edge edge : _edges) {
+            if (edge.getTo().getName().equals(aNode.getName())) {
+                result.add(edge);
+            }
+        }
+        return result;
+    }
+
+    public void accept(Visitor aVisitor) {
+        List<Node> nodes = getNodes(); // copy to make sure the visitor can
+                                        // modify the
+        // list of nodes as part of the loop.
+        List<Edge> edges = getEdges(); // copy ..... (see above).
+
+        for (Node node : nodes) {
+            aVisitor.visitNode(node);
+        }
+        for (Edge edge : edges) {
+            aVisitor.visitEdge(edge);
+        }
+    }
+}