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1   /*
2    * Copyright 2004 Ronald Blaschke.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.rblasch.convert;
17  
18  import org.rblasch.convert.converters.ChainedConverter;
19  import org.rblasch.convert.dijkstra.ShortestPathEngine;
20  import org.rblasch.convert.graph.Graphs;
21  import org.rblasch.convert.graph.Path;
22  import org.rblasch.convert.graph.WeightedDirectedGraph;
23  import org.rblasch.convert.type.Type;
24  
25  import java.util.Collection;
26  import java.util.HashSet;
27  import java.util.Iterator;
28  import java.util.LinkedList;
29  import java.util.List;
30  import java.util.Set;
31  
32  public class ShortestPathLookup implements ConverterLookup {
33      private final WeightedDirectedGraph graph;
34  
35      public ShortestPathLookup(final WeightedDirectedGraph g) {
36          this.graph = g;
37      }
38  
39      public void addGraph(final WeightedDirectedGraph g) {
40          Graphs.mergeInto(graph, g);
41      }
42  
43      public void addType(final Type t) {
44          graph.addVertex(new TypeVertex(t));
45      }
46  
47      public void addConverter(final MetaConverter mc) {
48          graph.addConnection(new TypeVertex(mc.getSourceType()),
49                  new ConverterEdge(mc, mc.getWeight()),
50                  new TypeVertex(mc.getDestinationType()));
51      }
52  
53      public void addAllConverters(final Collection/*<MetaConverter>*/ mcs) {
54          for (final Iterator i = mcs.iterator(); i.hasNext();) {
55              addConverter((MetaConverter) i.next());
56          }
57      }
58  
59      public int getNumberOfKnownTypes() {
60          return graph.getVertices().size();
61      }
62  
63      public int getNumberOfKnownConversions() {
64          return graph.getEdges().size();
65      }
66  
67      public Set/*<Type>*/ getAllKnownTypes() {
68          final Set/*<Type>*/ types = new HashSet();
69          for (final Iterator i = graph.getVertices().iterator(); i.hasNext();) {
70              final TypeVertex tv = (TypeVertex) i.next();
71              types.add(tv.getType());
72          }
73          return types;
74      }
75  
76      private List /*<MetaConverter>*/ getConvertersForPath(final Path path) {
77          final List /*<MetaConverter>*/ converters = new LinkedList();
78  
79          for (final Iterator i = path.getEdges().iterator(); i.hasNext();) {
80              final MetaConverter c = ((ConverterEdge) i.next()).getConverter();
81              converters.add(c);
82          }
83  
84          return converters;
85      }
86  
87      private Path getShortestPath(final Type sourceType, final Type destinationType) throws NoSuchConversionException {
88          final ShortestPathEngine spEngine = new ShortestPathEngine(graph);
89          final Path shortestPath = spEngine.getShortestPath(new TypeVertex(sourceType), new TypeVertex(destinationType));
90          if (shortestPath == null || shortestPath.getEdges().isEmpty()) {
91              throw new NoSuchConversionException("No conversion from " + sourceType + " to " + destinationType + " in " + graph);
92          }
93          return shortestPath;
94      }
95  
96      public MetaConverter lookup(final Type sourceType, final Type destinationType) throws NoSuchConversionException {
97          return new ChainedConverter(getConvertersForPath(getShortestPath(sourceType, destinationType)));
98      }
99  
100     public boolean equals(final Object obj) {
101         return graph.equals(obj);
102     }
103 
104     public int hashCode() {
105         return graph.hashCode();
106     }
107 
108     String dumpGraph() {
109         return graph.toString();
110     }
111 }