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Diffstat (limited to 'sca-java-1.x/branches/sca-java-1.0.1/modules/databinding/src/main/java/org/apache/tuscany/sca/databinding/impl/DirectedGraph.java')
-rwxr-xr-x | sca-java-1.x/branches/sca-java-1.0.1/modules/databinding/src/main/java/org/apache/tuscany/sca/databinding/impl/DirectedGraph.java | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/sca-java-1.x/branches/sca-java-1.0.1/modules/databinding/src/main/java/org/apache/tuscany/sca/databinding/impl/DirectedGraph.java b/sca-java-1.x/branches/sca-java-1.0.1/modules/databinding/src/main/java/org/apache/tuscany/sca/databinding/impl/DirectedGraph.java new file mode 100755 index 0000000000..6ecc1c6cd8 --- /dev/null +++ b/sca-java-1.x/branches/sca-java-1.0.1/modules/databinding/src/main/java/org/apache/tuscany/sca/databinding/impl/DirectedGraph.java @@ -0,0 +1,363 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.tuscany.sca.databinding.impl; + +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.LinkedList; +import java.util.List; +import java.util.Map; +import java.util.Set; + +/** + * Directed, weighted graph + * + * @param <V> The type of vertex object + * @param <E> The type of edge object + */ +public class DirectedGraph<V, E> { + private final Map<V, Vertex> vertices = new HashMap<V, Vertex>(); + + /** + * Key for the shortest path cache + */ + private final class VertexPair { + private Vertex source; + + private Vertex target; + + /** + * @param source + * @param target + */ + private VertexPair(Vertex source, Vertex target) { + super(); + this.source = source; + this.target = target; + } + + @Override + public boolean equals(Object object) { + if (!VertexPair.class.isInstance(object)) { + return false; + } + VertexPair pair = (VertexPair)object; + return source == pair.source && target == pair.target; + } + + @Override + public int hashCode() { + int x = source == null ? 0 : source.hashCode(); + int y = target == null ? 0 : target.hashCode(); + return x ^ y; + } + + } + + private final Map<VertexPair, Path> paths = new HashMap<VertexPair, Path>(); + + /** + * Vertex of a graph + */ + public final class Vertex { + private V value; + + // TODO: Do we want to support multiple edges for a vertex pair? If so, + // we should use a List instead of Map + private Map<Vertex, Edge> outEdges = new HashMap<Vertex, Edge>(); + + private Vertex(V value) { + this.value = value; + } + + @Override + public String toString() { + return "(" + value + ")"; + } + + public V getValue() { + return value; + } + + public Map<Vertex, Edge> getOutEdges() { + return outEdges; + } + + } + + /** + * An Edge connects two vertices in one direction + */ + public final class Edge { + private Vertex sourceVertex; + + private Vertex targetVertex; + + private E value; + + private int weight; + + public Edge(Vertex source, Vertex target, E value, int weight) { + this.sourceVertex = source; + this.targetVertex = target; + this.value = value; + this.weight = weight; + } + + @Override + public String toString() { + return sourceVertex + "->" + targetVertex + "[" + value + "," + weight + "]"; + } + + public E getValue() { + return value; + } + + public void setValue(E value) { + this.value = value; + } + + public Vertex getTargetVertex() { + return targetVertex; + } + + public void setTargetVertex(Vertex vertex) { + this.targetVertex = vertex; + } + + public int getWeight() { + return weight; + } + + public void setWeight(int weight) { + this.weight = weight; + } + + public Vertex getSourceVertex() { + return sourceVertex; + } + + public void setSourceVertex(Vertex sourceVertex) { + this.sourceVertex = sourceVertex; + } + } + + private final class Node implements Comparable<Node> { + + private long distance = Integer.MAX_VALUE; + + private Node previous; // NOPMD by rfeng on 9/26/06 9:17 PM + + private Vertex vertex; // NOPMD by rfeng on 9/26/06 9:17 PM + + private Node(Vertex vertex) { + this.vertex = vertex; + } + + public int compareTo(Node o) { + return (distance > o.distance) ? 1 : ((distance == o.distance) ? 0 : -1); + } + } + + public void addEdge(V source, V target, E edgeValue, int weight) { + Vertex s = getVertex(source); + if (s == null) { + s = new Vertex(source); + vertices.put(source, s); + } + Vertex t = getVertex(target); + if (t == null) { + t = new Vertex(target); + vertices.put(target, t); + } + Edge edge = new Edge(s, t, edgeValue, weight); + s.outEdges.put(t, edge); + } + + public Vertex getVertex(V source) { + Vertex s = vertices.get(source); + return s; + } + + public boolean removeEdge(V source, V target) { + Vertex s = getVertex(source); + if (s == null) { + return false; + } + + Vertex t = getVertex(target); + if (t == null) { + return false; + } + + return s.outEdges.remove(t) != null; + + } + + public Edge getEdge(Vertex source, Vertex target) { + return source.outEdges.get(target); + } + + public Edge getEdge(V source, V target) { + return getEdge(getVertex(source), getVertex(target)); + } + + /** + * Get the shortes path from the source vertex to the target vertex using + * Dijkstra's algorithm. If there's no path, null will be returned. If the + * source is the same as the target, it returns a path with empty edges with + * weight 0. + * + * @param sourceValue The value identifies the source + * @param targetValue The value identifies the target + * @return The shortest path + */ + public Path getShortestPath(V sourceValue, V targetValue) { + Vertex source = getVertex(sourceValue); + if (source == null) { + return null; + } + Vertex target = getVertex(targetValue); + if (target == null) { + return null; + } + + VertexPair pair = new VertexPair(source, target); + if (paths.containsKey(pair)) { + return paths.get(pair); + } + + // HACK: To support same vertex + if (source == target) { + Path path = new Path(); + Edge edge = getEdge(source, target); + if (edge != null) { + path.addEdge(edge); + } + paths.put(pair, path); + return path; + } + + Map<Vertex, Node> nodes = new HashMap<Vertex, Node>(); + for (Vertex v : vertices.values()) { + Node node = new Node(v); + if (v == source) { + node.distance = 0; + } + nodes.put(v, node); + } + + Set<Node> otherNodes = new HashSet<Node>(nodes.values()); + Set<Node> nodesOnPath = new HashSet<Node>(); + while (!otherNodes.isEmpty()) { + Node nextNode = extractMin(otherNodes); + if (nextNode.vertex == target) { + Path path = getPath(nextNode); + paths.put(pair, path); // Cache it + return path; + } + nodesOnPath.add(nextNode); + for (Edge edge : nextNode.vertex.outEdges.values()) { + Node adjacentNode = nodes.get(edge.targetVertex); + if (nextNode.distance + edge.weight < adjacentNode.distance) { + adjacentNode.distance = nextNode.distance + edge.weight; + adjacentNode.previous = nextNode; + } + } + } + paths.put(pair, null); // Cache it + return null; + } + + /** + * Searches for the vertex u in the vertex set Q that has the least d[u] + * value. That vertex is removed from the set Q and returned to the user. + * + * @param nodes + * @return + */ + private Node extractMin(Set<Node> nodes) { + Node node = Collections.min(nodes); + nodes.remove(node); + return node; + } + + /** + * The path between two vertices + */ + public final class Path { + private List<Edge> edges = new LinkedList<Edge>(); + + private int weight; + + public int getWeight() { + return weight; + } + + public List<Edge> getEdges() { + return edges; + } + + public void addEdge(Edge edge) { + edges.add(0, edge); + weight += edge.weight; + } + + @Override + public String toString() { + return edges + ", " + weight; + } + } + + private Path getPath(Node t) { + if (t.distance == Integer.MAX_VALUE) { + return null; + } + Path path = new Path(); + Node u = t; + while (u.previous != null) { + Edge edge = getEdge(u.previous.vertex, u.vertex); + path.addEdge(edge); + u = u.previous; + } + return path; + } + + @Override + public String toString() { + StringBuffer sb = new StringBuffer(); + for (Vertex v : vertices.values()) { + sb.append(v.outEdges.values()).append("\n"); + } + return sb.toString(); + } + + public Map<V, Vertex> getVertices() { + return vertices; + } + + public void addGraph(DirectedGraph<V, E> otherGraph) { + for (Vertex v : otherGraph.vertices.values()) { + for (Edge e : v.outEdges.values()) { + addEdge(e.sourceVertex.value, e.targetVertex.value, e.value, e.weight); + } + } + } +} |